Automatic Transmission - 4l80-e/4l85-e (Service & Replacement) Chevrolet Chevy Express H2500

Transmission Fluid Temperature (TFT) Sensor Specifications

Transmission Fluid Temperature (TFT) Sensor Specifications

Fastener Tightening Specifications

FASTENER TIGHTENING SPECIFICATIONS

Transmission General Specifications

Transmission General Specifications

Fluid Capacity Specifications

Fluid Capacity Specifications

Scheme 636

Shift Solenoid Valve State and Gear Ratio

Shift Solenoid Valve State & Gear Ratio

Scheme 637

Transmission Range Switch Logic

Transmission Range Switch Logic

Transmission Fluid Pressure (TFP) Manual Valve Position Switch Logic

Transmission Fluid Pressure (TFP) Manual Valve Position Switch Logic

Line Pressure

Line Pressure

Component Resistance

Component Resistance

Schematic and Routing Diagrams

For Chevy Express, see

1. G1500: «TRANSMISSION»(ref-154376-S03066575052003051400000)
2. G2500: «TRANSMISSION»(ref-154377-S02846009392003051400000)
3. G3500: «TRANSMISSION»(ref-154378-S04237305592003051400000)
4. H1500: «TRANSMISSION»(ref-154379-S03617912372003051400000)
5. H2500: «TRANSMISSION»(ref-154380-S20555996792003051400000)

For Cutaway 3500, see TRANSMISSION .

For RV Cutaway 3500, see TRANSMISSION .

For GMC Savana, see

1. G1500: «TRANSMISSION»(ref-154351-S22870193142003051400000)
2. G2500: «TRANSMISSION»(ref-154352-S13009096022003051400000)
3. G3500: «TRANSMISSION»(ref-154353-S25558473092003051400000)
4. H1500: «TRANSMISSION»(ref-154354-S29076241092003051400000)
5. H2500: «TRANSMISSION»(ref-154355-S27359042302003051400000)

For Savana Camper Special 3500, see TRANSMISSION .

For Savana Special 3500, see TRANSMISSION .

Scheme 638

Scheme 639

Scheme 640

Scheme 641

Scheme 642

Scheme 643

Scheme 644

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Scheme 647

Scheme 648

Scheme 649

Scheme 650

Scheme 651

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Scheme 653

Scheme 654

Scheme 655

Scheme 656

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Scheme 660

Scheme 661

Scheme 662

Scheme 663

Scheme 664

Scheme 665

Scheme 666

Scheme 667

Scheme 668

Scheme 669

Diagnostic Starting Point - Automatic Transmission

Begin the system diagnosis with DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS . The Powertrain OBD System Check provides the following information

1. The identification of the control modules which commands the system.
2. The ability of the control modules to communicate through the serial data circuit.
3. The identification and status of stored diagnostic trouble codes (DTCs).

The use of DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS identifies the correct procedure for diagnosing the system and where the procedure is located.

Symptoms

When it has been determined through DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS that no DTCs are present, begin symptom diagnosis by reviewing the Transmission Component and System Description . Reviewing Transmission Component and System Description information enables you to understand the operation of the system. This helps you determine if the condition described by the customer is normal or if a malfunction exists. If it is determined that a malfunction exists, identify the concern by referring to Symptoms - Automatic Transmission . Symptoms - Automatic Transmission provides common diagnostic categories which relate directly to diagnostic information or procedures.

Circuit Description

The Diagnostic System Check - Automatic Transmission is an organized approach to identify a condition created by an automatic transmission. The Diagnostic System check is the diagnostic starting point for an automatic transmission concern. The Diagnostic System Check directs you to the next logical step for diagnosing a transmission concern. Perform this check only if there is a driveability concern or if you have been directed here from another service information section.

Follow the table to help reduce diagnostic time and help prevent unnecessary replacement of good parts.

Diagnostic Aids

Important

1. Do not clear the DTC unless directed by a diagnostic procedure. Clearing the DTCs will erase all Freeze Frame and Failure Records stored in PCM memory.
2. Poor engine performance can sometimes be diagnosed as a transmission driveability condition. In order to avoid mis-diagnosis of the automatic transmission, always perform «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/chevrolet/chevy-express-h2500/2003-2003/remont/testing-diagnostics/#engine-controls-self-diagnostics-48l-53l-60l-gasoline) .
3. Use a scan tool that is known to function correctly. If necessary, test the scan tool on another vehicle.
4. Ensure the scan tool contains the most current file available.
5. The scan tool will display a loss of communication error message under the following conditions: PCM power is interrupted The ignition switch is turned OFF The battery voltage level is very low A poor connection at the diagnostic link connector (DLC)

Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. 1. This step determines if the scan tool is receiving power through the DLC connector.
2. 2. The MIL should illuminate whenever the ignition is ON and the engine is not running.
3. 3. This step determines if the PCM is transmitting Class 2 serial data to the DLC and that the Class 2 data circuit is not open or shorted.
4. 4. This step determines if a DTC is current or stored in history.

Scheme 670

Scheme 671

Scheme 672

Scheme 673

Scheme 674

Transmission Scan Tool Data List

Use the Scan Tool Data List under the following conditions

1. The Powertrain On-Board Diagnostic (OBD) System Check is complete.
2. The On-Board Diagnostics are functioning properly.
3. No DTCs are present.

The values below represent a typical display recorded from a properly functioning system.

Important: Do not use a scan tool that displays faulty data. Report the condition to the scan tool manufacturer. The use of a faulty scan tool can result in misdiagnosis and the unnecessary replacement of parts.

Only the parameters listed below are used in this manual for diagnosing. If a scan tool displays other parameters, the values are not recommended by General Motors for use in diagnosis.

Scan tool values below were recorded under the following conditions

1. Engine at idle
2. Upper radiator hose hot
3. Closed throttle
4. Transmission in Park
5. Closed Loop Operation
6. Accessories OFF
7. Brake pedal not applied

Transmission Scan Tool Data List

Transmission Scan Tool Data Definitions

1-2 Shift Error: This parameter is the difference between the desired 1-2 shift time and the actual 1-2 shift time. A positive number indicates the actual shift time was longer than the desired shift time.

1-2 Shift Time: This parameter is the actual time of the last 1-2 shift. The shift time is based on the gear ratio change after the commanded 1-2 shift. This value is only accurate if the adaptable shift parameter indicates Yes.

1-2 Solenoid: Displays ON or OFF. These parameters are the commanded status of the 1-2 shift solenoid valve. ON represents a commanded energized state. Current is flowing through the solenoid. OFF represents a non-commanded state. Current is not flowing through the solenoid.

1-2 Solenoid Open/Short to Ground: Displays Yes or No. This parameter indicates if an open or a short to ground exists in the feedback signal from the 1-2 shift solenoid valve to the PCM.

1-2 Solenoid Short to Volts: Displays Yes or No. This parameter indicates if a short to B+ exists in the feedback signal from the 1-2 shift solenoid valve to the PCM.

1-2 TAP Cell (4-16): Displays kPa or psi. This parameter displays the amount of pressure varied from a calibrated base line pressure for shifts. Each TAP cell is based on a calibrated shift torque value.

Each TAP cell value is calculated from the last shift time. This cell pressure is used in addition to the calibrated base line pressure to adjust the apply of a clutch or band during the next shift.

2-3 Shift Error: This parameter is the difference between the desired 2-3 shift time and the actual 2-3 shift time. A positive number indicates the actual shift time was longer than the desired shift time.

2-3 Shift Time: This parameter is the actual time of the last 2-3 shift. The shift time is based on the gear ratio change after the commanded 2-3 shift. This value is only accurate if the adaptable shift parameter indicates Yes.

2-3 Solenoid: Displays ON or OFF. These parameters are the commanded status of the 2-3 shift solenoid valve. ON represents a commanded energized state. Current is flowing through the solenoid. OFF represents a non-commanded state. Current is not flowing through the solenoid.

2-3 Solenoid Open/Short to Ground: Displays Yes or No. This parameter indicates if an open or a short to ground exists in the feedback signal from the 2-3 shift solenoid valve to the PCM.

2-3 Solenoid Short to Volts: Displays Yes or No. This parameter indicates if a short to B+ exists in the feedback signal from the 2-3 shift solenoid valve to the PCM.

2-3 TAP Cell (4-16): Displays kPa or psi. This parameter displays the amount of pressure varied from a calibrated base line pressure for shifts. Each TAP cell is based on a calibrated shift torque value. Each TAP cell value is calculated from the last shift time. This cell pressure is used in addition to the calibrated base line pressure to adjust the apply of a clutch or band during the next shift.

3-4 Shift Error: This parameter is the difference between the desired 3-4 shift time and the actual 3-4 shift time. A positive number indicates the actual shift time was longer than the desired shift time.

3-4 Shift Time: This parameter is the actual time of the last 3-4 shift. The shift time is based on the gear ratio change after the commanded 3-4 shift.

4WD: Displays Enabled or Disabled. This parameter indicates whether the vehicle is currently in a four-wheel drive mode.

4WD Low: Displays Enabled or Disabled. This parameter is the signal state of the four-wheel drive low circuit. Enabled indicates a 0 voltage signal requesting 4WD low. Disabled indicates a B+ voltage signal which does not request 4WD low.

A/C Clutch: Displays ON or OFF. This represents the commanded state of the A/C clutch control relay. The clutch should be engaged whenever ON is displayed. The PCM compensates for the additional engine load that is accompanied with the A/C clutch engaged.

Commanded Gear: Displays 1, 2, 3, or 4. This parameter indicates the current commanded state of the shift solenoids.

Cruise: Displays ENABLED or DISABLED. This parameter indicates whether the PCM is allowing cruise operation. The PCM has the ability to disable cruise control under certain conditions.

Current TAP (Transmission Adaptive Pressure) Cell: Displays cells 4-16. This parameter indicates the current TAP cell in use for transmission line pressure adaptation. The cells are based on engine torque. The higher the engine torque, the higher the current TAP cell. The last cell used will remain displayed until the next adaptable upshift occurs.

ECT (Engine Coolant Temperature): This parameter is the input signal of the engine coolant temperature sensor. Engine coolant temperature is high when the signal voltage is low, 0 volts, and engine coolant temperature is low when the signal voltage is high, 5 volts.

Engine Run Time: This parameter measures how long the engine has been operating. When you turn the ignition switch OFF, the value resets to zero.

Engine Speed: This parameter indicates the rotational speed of the engine expressed as revolutions per minute.

Engine Torque: This parameter is a calculated value based on engine load, throttle position, mass airflow, and other engine inputs. This parameter is accurate to within 15 ft/lb of actual measured engine torque.

Gear Ratio: This parameter is the actual gear ratio of the current commanded gear. In the commanded gear of R, D3, D2, and D1, it is calculated by dividing the input speed by the output speed. In the current gear of D4 with TCC lock up, the gear ratio is calculated by dividing the turbine speed by the output speed.

Ignition Voltage: This parameter represents the system voltage measured by the PCM at the ignition feed.

Last Shift Time: This parameter is the actual shift time of the last upshift.

PC (Pressure Control) Solenoid Act. (Actual) Current: This parameter is the actual current of the pressure control solenoid circuit at the control module. Zero amp (no current flow) indicates an actual higher line pressure. A reading of 1.1 amp, high current flow, indicates an actual lower line pressure.

PC (Pressure Control) Solenoid Duty Cycle: This parameter is the commanded state of the pressure control solenoid expressed as a percentage of energized ON time. A reading of 0 percent indicates zero ON time, non energized, or no current flow. Approximately 60 percent at idle indicates maximum ON time, energized, or high current flow.

PC (Pressure Control) Solenoid Ref. (Reference) Current: This parameter is the commanded current of the pressure control solenoid circuit at the control module. Zero amp, no current flow, indicates a commanded higher line pressure. A reading of 1.1 amp, high current flow, indicates a commanded lower line pressure.

Power Take-Off: Displays ON or OFF. This parameter indicates when the Power Take Off (PTO) is engaged. PTO mode disables all transmission diagnostics.

Speed Ratio: This parameter indicates engine speed divided by transmission output speed.

TCC Brake Switch (Gas Application): Displays Open or Closed. This parameter indicates the state of the TCC brake switch circuit input. Open indicates a zero voltage input. The brake switch is open and the brake pedal is applied. Closed indicates a B+ voltage input. The brake switch is closed and the brake pedal is not applied.

TCC Duty Cycle: This parameter is the commanded percentage of ON time of the TCC PWM solenoid. 90 percent represents an ON, energized, commanded state. 0 percent represents an OFF, non-energized, commanded state.

TCC Duty Cycle Open/Short to Ground: Displays Yes or No. This parameter indicates if an open or a short to ground exists in the feedback signal from the TCC PWM solenoid valve to the PCM.

TCC Duty Short to Volts: Displays Yes or No. This parameter indicates if a short to B+ exists in the feedback signal from the TCC PWM solenoid valve to the PCM.

TCC (Torque Converter Clutch) Slip Speed: This parameter is the difference between transmission input speed and engine speed. A negative value indicates that the engine speed is less than the input speed, deceleration. A positive value indicates that the engine speed is greater than the input speed, acceleration. A value of zero indicates that the engine speed is equal to the input speed, TCC is applied.

TFP Sw.: Displays Park/Neutral, Reverse, Drive4, Drive3, Drive2, Drivel or Invalid. This parameter is the decoded status of the three A/B/C inputs from the automatic transmission fluid pressure manual valve position switch. Invalid is displayed when the PCM does not recognize a valid combination of inputs.

TFP Switch A/B/C: Displays HI/LOW, HI/LOW, HI/LOW. These parameters are the three inputs from the automatic transmission fluid pressure manual valve position switch Assembly. HI represents a 0 voltage signal. LOW represents a B+ voltage signal.

TFT (Transmission Fluid Temperature) Sensor: When the transmission fluid is cold, the sensor resistance is high and the PCM senses a high signal voltage. As the transmission fluid temperature warms to normal operating temperature, the sensor resistance becomes less and the voltage decreases to about 1.5-2.0 volts.

TP (Throttle Position) Angle: The TP angle is computed by the PCM from TP voltage. The TP angle should display 0 percent at idle and 100 percent at wide open throttle (WOT).

TP Indicated Angle: This parameter indicates the PCM desired throttle angle for operating conditions present at the time.

TP (Throttle Position) Sensor: The PCM uses the TP sensor in order to determine the amount of throttle demanded. Voltage is below 1 volt at idle. Voltage is above 4 volts at wide open throttle (WOT).

Tow/Haul Mode: Displays Yes or No. This parameter indicates when the transmission is operating in a Tow/Haul mode. In Tow/Haul mode, the PCM commands a different shift pattern that increases performance when towing and hauling. Shift quality and TCC scheduling are also affected during Tow/Haul mode operation.

Traction Control: Displays Active or Inactive. When the PCM receives a request for torque reduction from the electronic brake control module, Active is displayed.

Transfer Case Ratio: This parameter indicates the ratio of the transfer case calculated by input speed divided by transmission output speed based on transmission commanded gear.

Trans. Fluid Temp. (TFT): This parameter is the input signal of the transmission fluid temperature sensor. Transmission fluid temperature is high when the signal voltage is low, 0 volts, and transmission fluid temperature is low when the signal voltage is high, 5 volts.

Trans. Slip Counter: Displays 0, 1 or 2. This parameter is the number of times the P0894 Diagnostic test has identified a slipping condition. This diagnostic test is required to identify a slipping condition three times in a row in order to set the DTC P0894 Transmission Component Slipping Diagnostic code.

Transmission Hot Mode: Displays ON or OFF. This parameter monitors the transmission fluid temperature. YES indicates that the transmission fluid temperature has exceeded 135°C (275°F).

Transmission ISS (Input Shaft Speed)

This parameter measures the rotational speed of the input shaft expressed as revolutions per minute.

Transmission OSS (Output Shaft Speed)

This parameter indicates the rotational speed of the transmission output shaft expressed as revolutions per minute. On four-wheel drive applications, the transfer case output shaft speed is measured.

TR Sw. A/B/C/P: Displays HI/LOW, HI/LOW, HI/LOW, HI/LOW. This parameter indicates the status of the four inputs from the transmission range switch to the PCM. HI indicates an ignition voltage input to the PCM. LOW indicates a zero voltage input to the PCM.

TR Sw.: Displays Park/Neutral, Reverse, Drive4, Drive3, Drive2, Drivel, or invalid. This parameter is the decoded status of the four A/B/C/P inputs from the transmission range switch. Invalid is displayed when the PCM does not recognize a valid combination of inputs.

Turbine Speed: This parameter indicates the rotational speed of the torque converter turbine shaft expressed as revolutions per minute. In commanded gears 1, 2, and 3, the turbine speed equals the input speed. In commanded gear 4, the turbine speed equals 3/4 of the input speed.

Vehicle Speed: This parameter is the input signal from the OSS sensor.

Diagnostic Trouble Code (DTC) Type Definitions

The DTC Type Definitions contain the characteristics for all types of DTCs. Each DTC type may or may not be found in this section. The DTC type is based on the action that the PCM takes when storing DTC information, and whether or not the PCM illuminates a service lamp or displays a message on a driver information center (DIC). The DTC descriptions in the Diagnostic Trouble Code List/Type are listed in numeric order and indicate the DTC types for domestic and export vehicle applications. Each DTC is categorized into one of the following types

Type A

This DTC is emissions related. The PCM stores the DTC in History, Freeze Frame and Failure Records during the first trip in which the conditions for setting the DTC are met. The PCM also illuminates the malfunction indicator lamp (MIL) during the first trip in which the conditions for setting the DTC are met.

Type B

This DTC is emissions related. The PCM stores the DTC in Failure Records during the first trip in which the conditions for setting the DTC are met. The PCM stores the DTC in History and Freeze Frame during the second consecutive trip in which the conditions for setting the DTC are met. The PCM also illuminates the MIL during the second consecutive trip in which the conditions for setting the DTC are met.

Type C

This DTC is non-emissions related. The PCM stores the DTC in History and Failure Records during the first trip in which the conditions for setting the DTC are met. The PCM does not store the DTC in Freeze Frame and does not illuminate the MIL. For some type C DTCs, a message may be displayed on a DIC, if equipped. For other type C DTCs, a separate service lamp, other than the MIL, may be illuminated. Type C DTCs that do not display a message on the DIC or illuminate a separate service lamp were formerly referred to as type D.

Type X

This DTC is available in the PCM software, but has been disabled, or turned off. In this case, the diagnostic does not run, DTCs are not stored, and the MIL does not illuminate. Type X DTCs are used primarily for export vehicles that do not require MIL illumination or DTC storing.

The service information contained in this manual refers to the domestic, federal, calibration package. Domestic calibrations apply to vehicles sold in the United States, Canada and Japan. Export calibrations exist for both leaded and unleaded vehicles. DTC types may change for some export vehicles, and some DTCs may be turned off for leaded export vehicles. Differences between domestic and export calibrations are not reflected on DTC support information pages. DTC types for export calibrations are referenced only in the Diagnostic Trouble Code List/Type.

Diagnostic Trouble Code (DTC) List/Type

Diagnostic Trouble Code (DTC) List/Type

Scheme 675

The flow of transmission fluid starts in the transmission pan. It is then drawn through the filter and transmission case into the oil pump assembly. The oil pump assembly pressurizes the fluid, line pressure, which becomes the main supply line of fluid. This fluid is directed to various components and hydraulic circuits within the transmission. The pressure regulator valve receives this fluid and directs it to the converter clutch shift valve. The converter clutch shift valve directs hot fluid leaving the torque converter or regulated converter feed fluid, through the cooler line to the transmission oil cooler. The transmission oil cooler is located in the radiator. The vehicle may also be equipped with an auxiliary oil cooler. The cooled fluid, center lube, is returned to the transmission through the return cooler line and into center lube port of the transmission. The automatic transmission fluid temperature (TFT) sensor, senses the fluid temperature in the transmission pan.

If the powertrain control module (PCM) detects a high TFT for a long period of time, then DTC P0218 sets. DTC P0218 is a type C DTC.

Conditions for Running the DTC

1. No TFT sensor DTC P0711, P0712 or P0713.
2. The system voltage is 8-18 volts.
3. The engine is running more than 7 seconds.

Conditions for Setting the DTC

The TFT is greater than 130°C (266°F) for greater than 600 seconds (10 minutes).

Action Taken When the DTC Sets

1. The PCM does not illuminate the malfunction indicator lamp (MIL).
2. The PCM freezes shift adapts from being updated.
3. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
4. The PCM stores DTC P0218 in PCM history.

Conditions for Clearing the DTC

1. A scan tool clears the DTC from PCM history.
2. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
3. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

1. Verify the customer driving habits, such as trailer towing, etc.
2. The scan tool transmission fluid temperature (TFT) should rise steadily during warm-up cycles then stabilize.
3. DTC P0218 may set approximately 600 seconds (10 minutes) after DTC P0711 has set. Follow the diagnostic table for DTC P0711 before proceeding to the diagnostic table for DTC P0218. Repairing the condition that set DTC P0711 will likely eliminate DTC P0218.

The number below refers to the step number on the diagnostic table.

1. 3. This step inspects for air restrictions and loss of transmission fluid flow, causing an extremely high TFT.

Scheme 676

Scheme 677

Scheme 678

The vehicle speed sensor (VSS), which is a permanent magnet generator, provides the vehicle speed information to the powertrain control module (PCM). The PM generator produces a pulsing AC voltage as the transmission speed sensors rotor teeth pass through the magnetic field of the sensor. The AC voltage level and the number of pulses increase as the speed of the vehicle increases. The PCM then converts the pulsing voltage to a digital signal for vehicle speed. The vehicle speed is used for engine and transmission calculations.

If the PCM detects a low vehicle speed and there is a high engine speed in a drive gear range, DTC P0502 sets. DTC P0502 is a type C DTC. For California emissions, DTC P0502 is a type B DTC.

1. No MAF sensor DTCs P0101, P0102 or P0103.
2. No MAP sensor DTCs P0106, P0107 or P0108.
3. No TP sensor DTCs P0121, P0122 or P0123.
4. No AT OSS DTC P0503.
5. No AT ISS DTCs P0716 or P0717.
6. No TFP manual valve position switch DTC P1810.
7. The engine torque must be between 108 N.m (80 lb ft) and: 4.8L: 542 N.m (400 lb ft) 6.0L: 576 N.m (425 lb ft)
8. No change in 4WD Low for at least 2 seconds.
9. The AT ISS is greater than 1,400 RPM.
10. The gear range is not PARK or NEUTRAL.
11. The system voltage is 8-18 volts.
12. Throttle angle is 10 percent or greater.

The AT OSS is less than 50 RPM for at least 4 seconds.

1. For California emission equipped vehicles, the PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. For Federal emission equipped vehicles, the MIL is not illuminated.
2. The PCM commands maximum line pressure.
3. The PCM freezes the shift adapts.
4. The PCM defaults a calculated output speed value by using the AT ISS values.
5. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame, California only, and Failure Records, California and Federal.
6. The PCM stores the DTC P0502 in PCM history during the second consecutive trip, California, or the first trip, Federal, in which the Conditions for Setting the DTC are met.

Conditions for Clearing the MIL/DTC

1. For California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. For California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
4. For Federal emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
5. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

DTC P0502 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine.

The numbers below refer to the step numbers on the diagnostic table.

1. 3. This step tests the AT VSS circuit.
2. 4. This step tests the integrity of the AT VSS sensor.

Scheme 679

Scheme 680

Scheme 681

The vehicle speed sensor (VSS), which is a permanent magnet generator, provides the vehicle speed information to the powertrain control module (PCM). The PM generator produces a pulsing AC voltage as the transmission speed sensors rotor teeth pass through the magnetic field of the sensor. The AC voltage level and the number of pulses increase as the speed of the vehicle increases. The PCM then converts the pulsing voltage to a digital signal for vehicle speed. The vehicle speed is used for engine and transmission calculations.

If the PCM detects a low vehicle speed and there is a high engine speed in a drive gear range, DTC P0503 sets. DTC P0503 is a type C DTC. For California emissions, DTC P0503 is a type B DTC.

1. No TFP manual valve position switch DTC P1810.
2. The system voltage is between 8-18 volts.
3. The engine is running for more than 7 seconds.
4. The gear range is not PARK or NEUTRAL.
5. No TFP manual valve position switch changes for greater than 6 seconds.
6. No 4WD Low switch change within 2 seconds.
7. No AT OSS increase greater than 250 RPM within 2 seconds.

The AT VSS has dropped greater than 1,000 RPM for at least 4 seconds.

1. For California emission equipped vehicles, the PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. For Federal emission equipped vehicles, the MIL is not illuminated.
2. The PCM commands maximum line pressure.
3. The PCM freezes the shift adapts.
4. The PCM defaults a calculated output speed value by using the AT ISS values.
5. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame, California only, and Failure Records, California and Federal.
6. The PCM stores the DTC P0503 in PCM history during the second consecutive trip, California, or the first trip, Federal, in which the Conditions for Setting the DTC are met.

1. For California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. For California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
4. For Federal emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
5. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

DTC P0503 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine.

The numbers below refer to the step numbers on the diagnostic table.

1. 3. This step tests the VSS assembly circuit.
2. 4. This step tests the integrity of the VSS assembly.

Scheme 682

Scheme 683

Scheme 684

Scheme 685

The transmission range (TR) switch is part of the park/neutral position and back-up lamp switch assembly and is externally mounted on the transmission manual shaft. The TR switch is a multi-signal switch. The powertrain control module (PCM) supplies ignition voltage to the TR switch on four signal circuits, A, B, C, and P. Each gear selector lever position grounds one or more of the switch circuits. In order to determine the gear range selected by the driver, the PCM compares the voltage combinations on the signal circuits to a look up table stored in the PCM memory. PCM detects the selected gear range by the state change of the switch input. Refer to Transmission Range Switch Logic .

Switch input to the PCM is represented on the scan tool as HI and Low. HI indicates an ignition voltage signal. Low indicates a zero voltage signal. The four parameters represent transmission range switch signal A, B, C and Parity.

DTC P0706 sets if the PCM detects vehicle speed in PARK or NEUTRAL range. DTC P0706 is a type C DTC.

1. No TPS DTCs P0121, P0122 or P0123.
2. No VSS DTCs P0502 or P0503.
3. No incorrect gear ratio DTC P0730.
4. Ignition voltage is 6-18 volts.
5. The engine is running for greater than 60 seconds.
6. The commanded gear is 3rd or 4th.
7. The throttle angle is 5 percent or greater.
8. The engine torque is greater than 68 N.m (50 lb ft).
9. The vehicle speed is 32 km/h (20 mph) or greater.
10. The PTO mode is not active.

The Conditions for Running the DTC are met and the PCM detects PARK or NEUTRAL.

1. The PCM will use TFP Switch to determine gear range.
2. The PCM does not illuminate the malfunction indicator lamp (MIL).
3. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
4. The PCM stores DTC P0706 in PCM history.

1. A scan tool can clear the DTC.
2. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
3. The PCM cancels the DTC default actions when the fault no longer exists and the DTC passes.

The numbers below refer to the step numbers on the diagnostic table.

1. 5. By disconnecting the transmission range switch, the ground path of all TR switch circuits would be removed and the PCM would recognize all circuits as open. The scan tool will display HI for all range signals.
2. 6. This step tests TR switch wiring for an open or the lack of the signal voltage from the PCM.
3. 7. This step tests TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the scan tool range signal A should change to LOW.
4. 8. This step tests TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the scan tool range signal B should change to LOW.
5. 9. This step tests TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the scan tool range signal C should change to LOW.

Scheme 686

Scheme 687

Scheme 688

Scheme 689

The automatic transmission fluid temperature (TFT) sensor is part of the 4L80-E automatic transmission (AT) wiring harness assembly. The TFT sensor is a resistor, or thermistor, which changes value based on temperature. The sensor has a negative temperature coefficient. This means that as the temperature increases, the resistance decreases, and as the temperature decreases the resistance increases. The powertrain control module (PCM) supplies a 5 volt reference signal to the sensor and measures the voltage drop in the circuit. When the transmission fluid is cold, the sensor resistance is high and the PCM detects high signal voltage. As the fluid temperature warms to a normal operating temperature, the resistance becomes less and the signal voltage decreases. The PCM uses this information to control shift quality and torque converter clutch apply.

If the PCM detects the TFT sensor resistance has no change, or an unrealistic change in a short amount of time, such as multiple changes within seconds, then DTC P0711 sets. DTC P0711 is a type C DTC.

1. No ECT DTCs P0117 or P0118.
2. No AT ISS DTC P0716 or P0717.
3. No VSS DTC P0502 or P0503.
4. No component slipping DTC P0894.
5. System voltage is 8-18 volts.
6. The engine is running for greater than 35 seconds.
7. The TFT is -40 to +21 °C (-40 to +70°F) at start up.
8. The engine coolant temperature (ECT) is 85°C (185°F) or greater.
9. ECT has changed at least 55°C (99°F) since start up.
10. The vehicle speed is 8 km/h (5 mph) or greater for 750 seconds (12.5 minutes) cumulatively.
11. The TCC slip speed is 60 RPM or greater for 500 seconds (8.3 minutes) cumulatively.

One of the following conditions occurs

Condition 1

The TFT has not changed more than 2.25°C (4°F), in more than 80 seconds. No TFT change.

Condition 2

Unrealistic TFT change of more than 20°C (36°F) 14 times in 7 seconds.

1. The PCM does not illuminate the malfunction indicator lamp (MIL).
2. The PCM commands increased line pressure.
3. The PCM freezes shift adapts.
4. The PCM determines a default transmission fluid temperature (TFT) using the following matrix: If the engine run time is less than 60 seconds then default TFT equals 47°C (117°F). If ECT is less than 20°C (68°F), then default TFT equals IAT. If the ECT is 20-110°C (68-230°F) then default TFT equals ECT. If the ECT is greater than 110°C (230°F) then default TFT is set to 140°C (284°F) and transmission shift pattern is in hot mode. If ECT and TFT DTCs are both set then default TFT is 140°C (284°F).
5. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
6. The PCM stores DTC P0711 in PCM history.

1. A scan tool clears the DTC from PCM history.
2. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
3. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

1. DTC P0218 may set approximately 600 seconds (10 minutes) after DTC P0711 has set. Follow the diagnostic table for DTC P0711 before proceeding to the diagnostic table for DTC P0218.
2. DTC P0711 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine.

The numbers below refer to the step numbers on the diagnostic table.

1. 2. This step inspects for proper transmission fluid level and condition.
2. 3. This step verifies which condition has set DTC P0711.
3. 5. The 12 volt test lamp is used as a fixed resistance.
4. 6. This step ensures that the PCM monitors the TFT Sensor Signal circuit (CKT 1227).

Scheme 690

Scheme 691

Scheme 692

The automatic transmission fluid temperature (TFT) sensor is part of the 4L80-E automatic transmission (AT) wiring harness assembly. The TFT sensor is a resistor, or thermistor, which changes value based on temperature. The sensor has a negative-temperature coefficient. This means that as the temperature increases, the resistance decreases, and as the temperature decreases the resistance increases. The powertrain control module (PCM) supplies a 5 volt reference signal to the sensor and measures the voltage drop in the circuit. When the transmission fluid is cold, the sensor resistance is high and the PCM detects high signal voltage. As the fluid temperature warms to a normal operating temperature, the resistance becomes less and the signal voltage decreases. The PCM uses this information to control shift quality and torque converter clutch apply.

If the PCM detects a continuous short to ground in the TFT sensor or signal circuit, then DTC P0712 sets. DTC P0712 is a type C DTC.

1. System voltage is 8-18 volts.
2. The engine is running for greater than 7 seconds.
3. No TFT DTC P0713.

The TFT sensor indicates a voltage of less than 0.14 volts for 17 seconds.

1. The PCM does not illuminate the malfunction indicator lamp (MIL).
2. The PCM commands increased line pressure.
3. The PCM freezes shift adapts.
4. The PCM determines a default transmission fluid temperature (TFT) using the following matrix: If the engine run time is less than 60 seconds then default TFT equals 47°C (117°F). If ECT is less than 20°C (68°F), then default TFT equals IAT. If the ECT is 20-110°C (68-230°F) then default TFT equals ECT. If the ECT is greater than 110°C (230°F) then default TFT is set to 140°C (284°F) and transmission shift pattern is in hot mode. If ECT and TFT DTCs are both set then default TFT is 140°C (284°F).
5. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
6. The PCM stores DTC P0712 in PCM history.

1. A scan tool clears the DTC from PCM history.
2. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
3. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

DTC P0712 defaults to an elevated line pressure, condition which may result in partial TCC apply, this: may produce an idle surge that could stall the engine.

The numbers below refer to the step numbers on the diagnostic table.

1. 3. This step tests for a short to ground or a skewed sensor by verifying the fault still exists.
2. 4. This step tests for an internal fault within the transmission by creating an open.

Scheme 693

Scheme 694

Scheme 695

The automatic transmission fluid temperature (TFT) sensor is part of the 4L80-E automatic transmission (AT) wiring harness assembly. The TFT sensor is a resistor, or thermistor, which changes value based on temperature. The sensor has a negative temperature coefficient. This means that as the temperature increases, the resistance decreases, and as the temperature decreases the resistance increases. The powertrain control module (PCM) supplies a 5 volt reference signal to the sensor and measures the voltage drop in the circuit. When the transmission fluid is cold, the sensor resistance is high and the PCM detects high signal voltage. As the fluid temperature warms to a normal operating temperature, the resistance becomes less and the signal voltage decreases. The PCM uses this information to control shift quality and torque converter clutch apply.

If the PCM detects a continuous open or short to voltage in the TFT signal circuit or the TFT sensor, then DTC P0713 sets. DTC P0713 is a type C DTC.

1. System voltage is 8-18 volts.
2. The engine is running for greater than 7 seconds.
3. No TFT sensor DTC P0712.

The TFT sensor indicates a voltage greater than 4.94 volts for 407 seconds (6.8 minutes).

1. The PCM does not illuminate the malfunction indicator lamp (MIL).
2. The PCM commands increased line pressure.
3. The PCM freezes shift adapts.
4. The PCM determines a default transmission fluid temperature (TFT) using the following matrix: If the engine run time is less than 60 seconds then default TFT equals 47°C (117°F). If ECT is less than 20°C (68°F), then default TFT equals IAT. If the ECT is 20-110°C (68-230°F) then default TFT equals ECT. If the ECT is greater than 110°C (230°F) then default TFT is set to 140°C (284°F) and transmission shift pattern is in hot mode. If ECT and TFT DTCs are both set then default TFT is 140°C (284°F).
5. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
6. The PCM stores DTC P0713 in PCM history.

1. A scan tool clears the DTC from PCM history.
2. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
3. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

DTC P0713 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine.

The numbers below refer to the step numbers on the diagnostic table.

1. 5. This step verifies a condition in the TFT sensor circuit inside the transmission.
2. 6. This step tests for higher than normal circuit voltage which may also damage the TFT sensor.

Scheme 696

Scheme 697

Scheme 698

The automatic transmission input shaft speed (AT ISS) sensor provides transmission input speed to the powertrain control module (PCM). The AT ISS sensor is a permanent magnet (PM) generator. The sensor mounts into the transmission case and maintains a slight air gap between the sensor and the forward clutch housing. The PM generator produces an AC voltage as the forward clutch housing rotor teeth pass through the sensor's magnetic field. The AC voltage level increases as the turbine shaft speed increases. The PCM converts the AC voltage into a digital signal. The PCM determines actual turbine speed using the digital signal. The PCM uses the input speed to calculate torque converter slip speed, and gear ratios.

When the PCM detects an unreasonably large change in the input speed, in a very short period of time, then DTC P0716 sets. DTC P0716 is a type C DTC. For California emissions, DTC P0716 is a type B DTC.

1. No TP sensor DTCs P0121, P0122 or P0123.
2. No VSS DTCs P0502 or P0503.
3. No ISS DTC P0717.
4. No 1-2 shift solenoid DTCs P0751, P0752 or P0753.
5. AT ISS DTC P0717 has run and passed.
6. The system voltage is 8-18 volts.
7. The TP angle is greater than 10 percent.
8. The vehicle speed is greater than 12 km/h (7 mph).

The input speed varies by 1,300 RPM for greater than 5 seconds.

1. The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip for all California emission equipped vehicles in which the Conditions for Setting the DTC are met.
2. The PCM commands maximum line pressure.
3. The PCM freezes shift adapts.
4. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame, California only, and Failure Records, California and Federal.
5. The PCM stores the DTC P0716 in PCM history during the second consecutive trip, California, or the first trip, Federal, in which the Conditions for Setting the DTC are met.

1. For California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. For California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
4. For Federal emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
5. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

DTC P0716 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine.

The number below refers to the step number on the diagnostic table.

1. 2. This step tests for proper operation of the AT ISS sensor.

Scheme 699

Scheme 700

Scheme 701

The automatic transmission input shaft speed (AT ISS) sensor provides transmission input speed to the powertrain control module (PCM). The AT ISS sensor is a permanent magnet generator. The sensor mounts into the transmission case and maintains a slight air gap between the sensor and the forward clutch housing. The PM generator produces an AC voltage as the forward clutch housing rotor teeth pass through the sensor's magnetic field. The AC voltage level increases as the turbine shaft speed increases. The PCM converts the AC voltage into a digital signal. The PCM determines actual turbine speed using the digital signal. The PCM uses the input speed to calculate torque converter slip speed, and gear ratios.

When the PCM detects a low or no input speed during high vehicle and high engine speeds, then DTC P0717 sets. DTC P0717 is a type C DTC. For California emissions vehicles, DTC P0717 is a type B DTC.

1. No VSS DTCs P0502 or P0503.
2. No TFP manual valve position switch DTC P1810.
3. The system voltage is 8-18 volts.
4. TFP manual valve position switch is not indicating PARK or NEUTRAL.
5. The vehicle speed is greater than 12 km/h (7 mph).

The input speed is less than 100 RPM for at least 5 seconds.

1. For California emission equipped vehicles, the PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. For Federal emission equipped vehicles, the MIL is not illuminated.
2. The PCM defaults the transmission to maximum line pressure.
3. The PCM freezes shift adapts.
4. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame, California only, and Failure Records, California and Federal.
5. The PCM stores the DTC P0717 in PCM history during the second consecutive trip, California, or the first trip, Federal, in which the Conditions for Setting the DTC are met.

1. For California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. For California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
4. For Federal emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
5. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

DTC P0717 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine.

The numbers below refer to the step numbers on the diagnostic table.

1. 3. This step tests for proper circuit operation up to the PCM connection.
2. 6. This step tests for proper operation of the AT ISS sensor.

Scheme 702

Scheme 703

Scheme 704

The TCC brake switch indicates the brake pedal status. The normally closed TCC brake switch supplies a B+ signal to the powertrain control module (PCM). The signal voltage circuit opens when the brakes are applied.

If the PCM detects an open TCC brake switch circuit during accelerations, then DTC P0719 sets. DTC P0719 is a type C DTC.

1. No VSS DTCs.
2. The ignition switch is in the ON position.
3. The system voltage is 8-18 volts.

DTC P0719 sets if the PCM detects an open brake switch or circuit, 0 volts, during vehicle acceleration and the following conditions occur eight times

1. The vehicle speed is less than 8 km/h (5 mph).
2. Then, the vehicle speed is 8-40 km/h (5-25 mph) for 1.7 seconds.
3. Then, the vehicle speed is greater than 40 km/h (25 mph) for 7 seconds.

1. The PCM does not illuminate the malfunction indicator lamp (MIL).
2. For TCC scheduling, the PCM disregards the brake switch state if the TP sensor is 1.5 percent or greater and the vehicle speed is 32 km/h (20 mph) or greater.
3. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
4. The PCM stores DTC P0719 in PCM history.

1. A scan tool clears the DTC from PCM history.
2. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
3. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

Inspect the brake switch for proper mounting and operation.

The numbers below refer to the step numbers on the diagnostic table.

1. 4. This step tests for TCC brake switch voltage to the PCM connector.
2. 7. This step isolates the TCC brake switch as a source for setting the DTC.
3. 10. This step tests for a short to ground in the voltage circuit (CKT 739) to the TCC brake switch.
4. 12. This step tests for a short to ground in the TCC brake switch circuit (CKT 420), from the TCC brake switch to the PCM.
5. 13. This step isolates the PCM as a source for causing the fuse to open.

Scheme 705

Scheme 706

Scheme 707

Scheme 708

The TCC brake switch indicates the brake pedal status. The normally closed TCC brake switch supplies a B+ signal to the powertrain control module (PCM). The signal voltage circuit opens when the brakes are applied.

If the PCM detects a closed TCC brake switch during decelerations, then DTC P0724 sets. DTC P0724 is a type C DTC.

1. No VSS DTCs.
2. The ignition switch is in the ON position.
3. The system voltage is 8-18 volts.

DTC P0724 sets if the PCM detects a closed brake switch or circuit, 12 volts, during vehicle deceleration and the following conditions occur ten times

1. The vehicle speed is greater than 40 km/h (25 mph) for 7 seconds.
2. Then, the vehicle speed is 8-40 km/h (5-25 mph) for 2.5 seconds.
3. Then, the vehicle speed is less than 8 km/h (5 mph).

1. The PCM does not illuminate the malfunction indicator lamp (MIL).
2. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
3. The PCM stores DTC P0724 in PCM history.

1. A scan tool clears the DTC from PCM history.
2. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
3. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

Inspect the brake switch for proper mounting and operation.

The number below refers to the step number on the diagnostic table.

1. 3. This step isolates the TCC Brake switch as a source for setting the DTC.

Scheme 709

Scheme 710

The powertrain control module (PCM) calculates the gear ratio based on the automatic transmission input shaft speed sensor (AT ISS) and the automatic transmission output shaft speed sensor (AT OSS) readings. The PCM compares the known transmission gear ratio to the calculated ratio for the selected gear ranges. Refer to Range Reference .

If the PCM detects an unknown transmission gear, ratio, then DTC P0730 sets. DTC P0730 is a type C DTC.

The engine is running longer than 7 seconds and not in fuel cut off.

1. The system voltage is 8-18 volts.
2. No MAP sensor DTCs P0106, P0107, or P0108.
3. No TP sensor DTCs P0121, P0122 or P0123.
4. No AT VSS DTCs P0502 or P0503.
5. No AT ISS DTCs P0716 or P0717.
6. No TFP manual valve position switch DTC P1810.
7. The vehicle speed is greater than 8 km/h (5 mph).
8. The TP angle is greater than 15 percent.
9. The TFT is greater than 20°C (68°F).
10. No gear range change for greater than 6.0 seconds.
11. The engine torque must be between 108 N.m (80 lb ft) and: 4.8L: 542 N.m (400 lb ft) 6.0L: 576 N.m (425 lb ft)
12. No 4WD Low DTC P1875.

1. The following conditions are met for 10 seconds.
2. The Gear Ratio is one of the following: Greater than 2.51 or less than 2.44 Greater than 1.51 or less than 1.44 Greater than 1.03 or less than 0.97 Greater than 2.12 or less than 2.05

1. The PCM does not illuminate the malfunction indicator lamp (MIL).
2. The PCM commands maximum line pressure.
3. The PCM freezes shift adapts.
4. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
5. The PCM stores DTC P0730 in PCM history.

1. A scan tool clears the DTC from PCM history.
2. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
3. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

1. A false or incorrect AT OSS or AT ISS signal can set DTC P0730.
2. DTC P0894 detects an incorrect gear ratio in fourth gear with TCC applied.
3. Inspect for any improperly installed aftermarket equipment.
4. Sticking or contamination of shift valves may cause intermittent incorrect gear ratios.
5. Refer to «Shift Solenoid Valve State and Gear Ratio»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__shift-solenoid-valve-state-and-gear) .
6. DTC P0730 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine.

The numbers below refer to the step numbers on the diagnostic table.

1. 3. This step tests the indicated range signal to the actual selected range. A faulty TFP manual valve position switch could set DTC P1810.
2. 4. This step tests for proper ratios in each commanded gear state.

Scheme 711

Scheme 712

Scheme 713

Important: DTC P0741 detects high torque converter clutch (TCC) slip speed in commanded 2nd and 3rd gears only. TCC is only commanded on in these gears during Hot Mode, WOT, or if the gear selector indicates DRIVE 3 or DRIVE 2.

The powertrain control module (PCM) energizes the torque converter clutch pulse width modulated (TCC PWM) solenoid valve by grounding the control circuit. This blocks the exhaust for TCC signal fluid and allows filtered 2-3 drive fluid to feed the TCC signal circuit. When the vehicle's operating conditions are appropriate for TCC application, the PCM increases the TCC duty cycle to approximately 30 percent. This allows TCC signal fluid pressure to move the converter clutch shift valve into the apply position and direct regulated apply fluid to the torque converter. The PCM then increases, ramps, the duty cycle to approximately 60 percent, where regulated apply fluid pressure, applies the converter clutch. The vehicle application determines the TCC apply rate. Once the TCC applies, the duty cycle immediately increases to approximately 70 percent to achieve full apply pressure, in the regulated apply fluid circuit.

The TCC PWM solenoid valve is de-energized by the PCM opening the control circuit. This action allows the TCC signal fluid to exhaust through the solenoid and blocks filtered 2-3 drive fluid from entering the TCC signal circuit. The loss of fluid pressure in the TCC signal circuit releases the TCC.

If the PCM detects high TCC slip when the TCC is commanded ON, then DTC P0741 sets. DTC P0741 is a type C DTC. For California emissions, DTC P0741 is a type B DTC.

1. No TP sensor DTCs P0121, P0122 or P0123.
2. No VSS DTCs P0502 or P0503.
3. No AT ISS DTCs P0716 or P0717.
4. No TCC DTCs P0742 or P1860.
5. No TFP manual valve position switch DTC P1810.
6. The system voltage is 8-18 volts.
7. The gear ratio must indicate 2nd or 3rd gear.
8. The TP is 10-100 percent.
9. The TFP manual valve position switch must be in D4, D3, or D2 and has not changed in 6 seconds.
10. The transmission fluid temperature (TFT) is 20-150°C (68-302°F).
11. TCC duty cycle is 60 percent or greater and locked on greater than 1 second.

1. The TCC slip speed is 125 RPM or greater, for 3 seconds.
2. All conditions must be met for a total of 4 occurrences.

1. For California emission equipped vehicles, the PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. For Federal emission equipped vehicles, the MIL is not illuminated.
2. The PCM inhibits the TCC.
3. The PCM increases line pressure.
4. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame, California only, and Failure Records, California and Federal.
5. The PCM stores the DTC P0741 in PCM history during the second consecutive trip, California or the first trip, Federal, in which the Conditions for Setting the DTC are met.

1. For California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. For California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
4. For Federal emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
5. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

1. Residue or contamination may cause valves to stick intermittently.
2. DTC P0741 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine.

The numbers below refer to the step numbers on the diagnostic table.

1. 2. This step tests for excessive TCC slip when TCC is commanded on.
2. 3. This step inspects for possible causes of no TCC apply.

Scheme 714

Scheme 715

Scheme 716

The powertrain control module (PCM) energizes the torque converter clutch pulse width modulated (TCC PWM) solenoid valve by grounding the control circuit. This blocks the exhaust for TCC signal fluid and allows filtered 2-3 drive fluid to feed the TCC signal circuit. When the vehicle operating conditions are appropriate for TCC application, the PCM increases the TCC duty cycle to approximately 30 percent. This allows TCC signal fluid pressure to move the converter clutch shift valve into the apply position and direct regulated apply fluid to the torque converter. The PCM then increases the duty cycle to approximately 60 percent, where regulated apply fluid pressure, applies the converter clutch. The vehicle application determines the TCC apply rate. Once the TCC applies, the duty cycle immediately increases to approximately 70 percent to achieve full apply pressure, in the regulated apply fluid circuit. The TCC PWM solenoid valve is de-energized by the PCM opening the control circuit. This action allows the TCC signal fluid to exhaust through the solenoid and blocks filtered 2-3 drive fluid from entering the TCC signal circuit. The loss of fluid pressure in the TCC signal circuit releases the TCC.

If the PCM detects low TCC slip when the TCC is commanded OFF, then DTC P0742 sets. DTC P0742 is a type C DTC. For California emissions, DTC P0742 is a type B DTC.

1. No MAP sensor DTCs P0106, P0107, or P0108.
2. No Transmission Component Slipping DTC P0894.
3. No TP sensor DTCs P0121, P0122 or P0123.
4. No VSS DTCs P0502 or P0503.
5. No AT ISS DTCs P0716 or P0717.
6. No TCC DTCs P0741 or P1860.
7. No TFP manual valve position switch DTC P1810.
8. The system voltage is 8-18 volts.
9. The speed ratio is 0.95-2.18.
10. The engine torque must be between 169 N.m (125 lb ft) and: 4.8L: 542 N.m (400 lb ft) 6.0L: 576 N.m (425 lb ft)
11. No TFP manual valve position switch change within 6 seconds.
12. The TFP manual valve position switch indicates D4.
13. The transmission fluid temperature (TFT) is 20-130°C (68-266°F).
14. The commanded gear is not 1st.
15. Engine speed is 800-4,400 RPM.
16. The throttle position (TP) is 12-100 percent.
17. Vehicle speed is 11-121 km/h (7-75 mph).

1. The TCC slip speed must be -15 to +15 RPM for at least 3 seconds.
2. All conditions met for 4 occurrences.

1. For California emission equipped vehicles, the PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. For Federal emission equipped vehicles, MIL is not illuminated.
2. The PCM commands maximum line pressure.
3. The PCM freezes shift adapts.
4. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame, California only, and Failure Records, California and Federal.
5. The PCM stores the DTC P0742 in PCM history during the second consecutive trip, California, or the first trip, Federal, in which the Conditions for Setting the DTC are met.

1. For California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. For California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
4. For Federal emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
5. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

1. If the TCC is mechanically stuck ON with the parking brake applied and any gear range selected, the TCC fluid mechanically applies the TCC. TCC fluid mechanically applying the TCC can cause an engine stall.
2. A stuck TP sensor may set a DTC P0742.
3. DTC P0742 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine.

The number below refers to the step number on the diagnostic table.

1. 3. This step tests the mechanical state of the TCC. When the PCM commands the TCC solenoid OFF, the slip speed should increase.

Scheme 717

Scheme 718

Scheme 719

The pressure control (PC) solenoid valve is a powertrain control module (PCM) controlled device that regulates the transmission line pressure. The PCM compares throttle position (TP) sensor voltage, engine RPM, and other inputs in order to determine the appropriate line pressure for a given load. The PCM regulates line pressure by applying a varying duty cycle to the PC solenoid valve based on the resistance of the solenoid, and the amperage needed to obtain optimum line pressure. The applied amperage varies from 0.1 amps for maximum line pressure to 1.1 amps for minimum line pressure.

If the PCM detects a PC duty cycle that exceeds 95 percent or less than 0.5 percent, then DTC P0748 sets. DTC P0748 is a type C DTC.

1. The system voltage is greater than 11 volts at -40°C (40°F) TFT or 12 volts at 150°C (302°F) TFT.
2. The engine must be running more than 300 RPM for at least 7 seconds, and not in fuel cut-off.
3. The pressure control solenoid is enabled.

1. The PC duty cycle exceeds 95 percent or is less than 0.5 percent.
2. All conditions are met for 700 milliseconds (0.7 seconds).

1. The PCM does not illuminate the malfunction indicator lamp (MIL).
2. The PCM disables the PC solenoid valve, defaulting the transmission to maximum line pressure.
3. The PCM freezes shift adapts.
4. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.
5. The PCM stores DTC P0748 in PCM history.

1. A scan tool clears the DTC from PCM history.
2. The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
3. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

1. Inspect for improperly wired aftermarket equipment.
2. DTC P0748 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine.

The numbers below refer to the step numbers on the diagnostic table.

1. 2. This step tests the ability of the PCM to command the PC solenoid valve.
2. 3. This step tests the PC solenoid valve and the AT wiring harness assembly for incorrect resistance.

Scheme 720

Scheme 721

Scheme 722

Scheme 723

The 1-2 shift solenoid (SS) valve controls the fluid flow action on the 1-2 and the 3-4 shift valves. The 1-2 SS valve is a normally open exhaust valve that is used with the 2-3 SS in order to allow four different shifting combinations.

When the powertrain control module (PCM) detects a 2-2-3-3 gear ratio, then DTC P0751 sets. DTC P0751 is a type C DTC. For California emissions vehicles DTC P0751 is a type B DTC.

1. No MAP sensor DTCs P0106, P0107, or P0108.
2. No TP sensor DTCs P0121, P0122 or P0123.
3. No AT ISS sensor DTCs P0716 or P0717.
4. No VSS DTCs P0502 or P0503.
5. No TFP manual valve position switch DTC P1810.
6. No TCC PWM solenoid valve DTC P1860.
7. No TCC Stuck ON DTC P0742.
8. The system voltage is 10-18 volts.
9. The AT OSS is greater than 7 RPM.
10. No MAF sensor DTC P0101, P0102 or P0103.
11. No shift solenoid electrical DTC P0753 or P0758.
12. Not in 4WD Low.
13. No Transmission Component Slipping DTC P0894.
14. AT ISS is greater than 7 RPM.
15. The TP sensor is 10-100 percent.
16. The engine torque must be between 108 N.m (80 lb ft) and: 4.8L: 542 N.m (400 lb ft) 6.0L: 576 N.m (425 lb ft)
17. No TFP manual valve position switch change within 6 seconds.
18. The TFP manual valve position switch indicates D4.
19. The transmission fluid temperature (TFT) is greater than 20°C (68°F) and less than 130°C (266°F).

1. The commanded gear equals 1st and the ratio equals 2nd for greater than 2 seconds.
2. The commanded gear equals 4th with the TCC locked and the ratio equals 3rd for greater than 3.75 seconds.
3. All conditions are met for 2 occurrences.

1. For California emission equipped vehicles, the PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. For Federal emission equipped vehicles, the MIL is not illuminated.
2. The PCM commands maximum line pressure.
3. The PCM freezes shift adapts.
4. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame, California only, and Failure Records, California and Federal.
5. The PCM stores the DTC P0751 in PCM history during the second consecutive trip, California, or the first trip, Federal, in which the Conditions for Setting the DTC are met.

1. For California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. For California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
4. For Federal emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
5. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

1. Verify that the transmission meets the specifications in the Shift Speed table. Refer to «Shift Speed»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
2. Other internal transmission failures can cause more than one shift to occur.
3. DTC P0751 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine.

The number below refers to the step number on the diagnostic table.

1. 2. This step tests that the PCM commanded all shifts, that all shift solenoid valves responded correctly, but that all the shifts did not occur.

Scheme 724

Scheme 725

The 1-2 shift solenoid (SS) valve controls the fluid flow action on the 1-2 and the 3-4 shift valves. The 1-2 SS valve is a normally open exhaust valve that is used with the 2-3 SS in order to allow four different shifting combinations.

When the powertrain control module (PCM) detects a 1-1-4-4 gear ratio, then DTC P0752 sets. DTC P0752 is a type C DTC. For California emissions vehicles DTC P0752 is a type B DTC.

1. No MAP sensor DTCs P0106, P0107, or P0108.
2. No TP sensor DTCs P0121, P0122 or P0123.
3. No ISS sensor DTCs P0716 or P0717.
4. No VSS DTCs P0502 or P0503.
5. No transmission component slipping DTC P0894.
6. No TFP manual valve position switch DTC P1810.
7. No TCC PWM solenoid valve DTC P1860.
8. No TCC Stuck ON DTC P0742.
9. The system voltage is 10-18 volts.
10. No MAF sensor DTC P0101, P0102 or P0103.
11. No shift solenoid electrical DTC P0753 or P0758.
12. Not in 4WD Low.
13. The AT OSS is greater than 7 RPM.
14. AT ISS is greater than 7 RPM.
15. The TP sensor is 10-100 percent.
16. The engine torque must be between 108 N.m (80 lb ft) and: 4.8L: 542 N.m (400 lb ft) 6.0L: 576 N.m (425 lb ft)
17. No TFP manual valve position switch change within 6 seconds.
18. The TFP manual valve position switch indicates D4.
19. The transmission fluid temperature (TFT) is greater than 20°C (68°F) and less than 130°C (266°F).

1. The commanded gear equals 2nd and the ratio equals 1st for greater than 2.25 seconds.
2. All conditions are met for 5 occurrences.

1. For California emission equipped vehicles, the PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. For Federal emission equipped vehicles, the MIL is not illuminated.
2. The PCM commands maximum line pressure.
3. The PCM inhibits 3-2 downshifts above 40 km/h (25 mph).
4. The PCM freezes shift adapts.
5. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame, California only, and Failure Records, California and Federal.
6. The PCM stores the DTC P0752 in PCM history during the second consecutive trip, California, or the first trip, Federal, in which the Conditions for Setting the DTC are met.

1. For California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. For California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
4. For Federal emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
5. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

1. Verify that the transmission meets the specifications in the Shift Speed table. Refer to «Shift Speed»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
2. Other internal transmission failures can cause more than one shift to occur.
3. DTC P0752 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine.

The number below refers to the step number on the diagnostic table.

1. 2. This step tests that the PCM commanded all shifts, that all shift solenoid valves responded correctly, but that all the shifts did not occur.

Scheme 726

Scheme 727

The 1-2 shift solenoid (SS) valve controls the fluid flow action on the 1-2 and the 3-4 shift valves. The 1-2 SS valve is a normally-open exhaust valve that is used with the 2-3 SS valve to allow for four different shifting combinations. The 1-2 SS valve attaches to the control valve body within the transmission. The ignition voltage goes directly to the 1-2 SS valve. The powertrain control module (PCM) controls the 1-2 SS valve by providing the ground path through the 1-2 shift solenoid valve control circuit.

When the PCM detects a continuous open or short in the 1-2 SS valve circuit or the 1-2 SS valve, then DTC P0753 sets. DTC P0753 is a type C DTC. For California emissions vehicles, DTC P0753 is a type A DTC.

1. The system voltage is 8-18 volts.
2. The engine runs more than 400 RPM for greater than 7 seconds.

All conditions for running the DTC are met, and either of the following conditions occur for 4.3 seconds out of 5 seconds.

1. The PCM commands the solenoid on, and the voltage input remains high, B+.
2. The PCM commands the solenoid off and the voltage input remains low.

1. For California emission equipped vehicles, the PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. For Federal emission equipped vehicles, the MIL is not illuminated.
2. The PCM commands maximum line pressure.
3. The PCM freezes shift adapts.
4. The PCM inhibits 3-2 downshifts above 40 km/h (25 mph).
5. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame, California only, and Failure Records, California and Federal.
6. The PCM stores the DTC P0753 in PCM history during the second consecutive trip, California, or the first trip, Federal, in which the Conditions for Setting the DTC are met.

1. For California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. For California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
4. For Federal emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
5. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

1. DTC P0753 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine.
2. An open ignition feed on the Off/Run/Crank voltage circuit (CKT 1020) can cause multiple DTCs to set.

The numbers below refer to the step numbers on the diagnostic table.

1. 4. This step tests the function of the 1-2 SS valve and the internal wiring harness.
2. 5. This step tests the power to the 1-2 SS valve from the ignition through the fuse.
3. 6. This step tests the ability of the PCM and the wiring to control the ground circuit.
4. 8. This step measures the resistance of the automatic transmission (AT) wiring harness assembly and the 1-2 SS valve.

Scheme 728

Scheme 729

Scheme 730

Scheme 731

The 2-3 shift solenoid (SS) valve controls fluid flow acting on the 2-3 shift valve. The 2-3 SS valve is a normally open exhaust valve used with the 1-2 SS valve in order to allow for four different shift combinations.

When the powertrain control module (PCM) detects a 4-3-3-4 gear ratio, then DTC P0756 sets. DTC P0756 is a type C DTC. For California emissions vehicles, DTC P0756 is a type A DTC.

1. No MAF sensor DTCs P0101, P0102 or P0103.
2. No MAP sensor DTCs P0106, P0107, or P0108.
3. No TP sensor DTCs P0121, P0122 or P0123.
4. No VSS DTCs P0502 or P0503.
5. No AT ISS DTCs P0716 or P0717.
6. No TFP manual valve position switch DTC P1810.
7. No shift solenoid electrical DTCs P0753 or P0758.
8. The AT OSS is greater than 7 RPM.
9. No TCC stuck ON DTC P0742.
10. No TCC PWM electrical DTC P1860.
11. No transmission component slipping DTC P0894.
12. Not in 4WD Low.
13. The AT ISS is greater than 7 RPM.
14. The system voltage is 10-18 volts.
15. The TP angle is greater than 10 percent.
16. The transmission fluid temperature (TFT) is greater than 20°C (68°F) and less than 130°C (266°F).
17. The engine torque must be between 108 N.m (80 lb ft) and: 4.8L: 542 N.m (400 lb ft) 6.0L: 576 N.m (425 lb ft)

1. The commanded gear equals 1st and the ratio equals 4th for greater than 2.5 seconds.
2. The commanded gear equals 2nd and the ratio equals 3rd for greater than 2.7 seconds.
3. All conditions are met for 2 occurrences.

1. The PCM illuminates the malfunction indicator lamp (MIL) for California emissions vehicles.
2. The PCM commands a soft landing to 2nd gear.
3. The PCM commands maximum line pressure.
4. The PCM freezes shift adapts.
5. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame, California only, and Failure Records, California and Federal.
6. The PCM stores DTC P0756 in PCM history.

1. For California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. For California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
4. For Federal emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
5. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

1. Verify that the transmission meets the specifications in the Shift Speed table. Refer to «Shift Speed»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
2. Other internal transmission failures may cause more than one shift to occur.
3. The customer may have a concern with an engine over-rev condition or neutral condition in 4th gear.
4. DTC P0756 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine.

The number below refers to the step number on the diagnostic table.

1. 2. This step tests that the PCM commanded all shifts, that all shift solenoid valves responded correctly, but that all the shifts did not occur.

Scheme 732

Scheme 733

The 2-3 shift solenoid (SS) valve controls fluid flow acting on the 2-3 shift valve. The 2-3 SS valve is a normally open exhaust valve used with the 1-2 SS valve in order to allow for four different shift combinations.

If the powertrain control module (PCM) detects a non third gear ratio while third gear is commanded, then DTC P0757 sets. DTC P0757 is a type C DTC. For California emissions vehicles, DTC P0757 is a type A DTC.

1. No MAF sensor DTCs P0101, P0102 or P0103.
2. No MAP sensor DTCs P0106, P0107, or P0108.
3. No TP sensor DTCs P0121, P0122 or P0123.
4. No VSS DTCs P0502 or P0503.
5. No AT ISS DTCs P0716 or P0717.
6. No TFP manual valve position switch DTC P1810.
7. No shift solenoid electrical DTCs P0753 or P0758.
8. No 4WD Low DTC P1875.
9. No TCC stuck ON DTC P0742.
10. Not in 4WD Low.
11. No transmission component slipping DTC P0894.
12. No TCC PWM electrical DTC P1860.
13. The AT ISS is greater than 7 RPM.
14. The AT OSS is greater than 7 RPM.
15. The system voltage is 10-18 volts.
16. The TP angle is greater than 10 percent.
17. The transmission fluid temperature (TFT) is greater than 20°C (68°F) and less than 130°C (266°F).
18. The engine torque must be between 108 N.m (80 lb ft) and: 4.8L: 542 N.m (400 lb ft) 6.0L: 576 N.m (425 lb ft)

1. The commanded gear equals 3rd and the ratio equals 2nd for greater than 2.25 seconds.
2. All conditions are met for 7 occurrences.

1. The PCM illuminates the malfunction indicator lamp (MIL) for California emissions vehicles.
2. The PCM commands a soft landing to 2nd gear.
3. The PCM commands maximum line pressure.
4. The PCM freezes shift adapts.
5. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame, California only, and Failure Records, California and Federal.
6. The PCM stores DTC P0757 in PCM history.

1. For California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. For California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
4. For Federal emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
5. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

1. Verify that the transmission meets the specifications in the Shift Speed table. Refer to «Shift Speed»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
2. Other internal transmission failures may cause more than one shift to occur.
3. The customer may have concern of an engine over-rev condition or neutral condition in 4th gear.
4. DTC P0757 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine.

The number below refers to the step number on the diagnostic table.

1. 2. This step tests that the PCM commanded all shifts, that all shift solenoid valves responded correctly, but that all the shifts did not occur.

Scheme 734

Scheme 735

The 2-3 shift solenoid (SS) valve controls fluid acting on the 2-3 shift valve. The 2-3 SS valve is a normally open exhaust valve used with the 1-2 SS valve in order to allow four different shifting combinations. The 2-3 SS valve attaches to the control valve body within the transmission. The ignition voltage goes directly to the 2-3 SS valve. The powertrain control module (PCM) controls the 2-3 SS valve by providing a ground path through the control circuit.

If the PCM detects a continuous open or short in the 2-3 SS valve circuit or the 2-3 SS valve, then DTC P0758 sets. DTC P0758 is a type C DTC. For California emissions vehicles, DTC P0758 is a type A DTC.

1. The system voltage is 8-18 volts.
2. The engine is running more than 400 RPM for more than 7 seconds.

The above conditions are met and either of the following conditions occur for 4.3 seconds out of 5 seconds.

1. The PCM commands the 2-3 SS valve ON, and the voltage input remains high, B+.
2. The PCM commands the 2-3 SS valve OFF, and the voltage input remains low, 0 volts.

1. The PCM illuminates the malfunction indicator lamp (MIL) for California emission vehicles.
2. The PCM commands a soft landing to second gear.
3. The PCM commands maximum line pressure.
4. The PCM freezes shift adapts form being updated.
5. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame, California only, and Failure Records, California and Federal.
6. The PCM stores DTC P0758 in PCM history.

1. For California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. For California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
4. For Federal emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
5. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

1. Refer to «Shift Solenoid Valve State and Gear Ratio»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__shift-solenoid-valve-state-and-gear) .
2. DTC P0758 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine.

The numbers below refer to the step numbers on the diagnostic table.

1. 4. This step tests the function of the 2-3 SS valve and the internal wiring harness.
2. 5. This step tests the power to the 2-3 SS valve from the ignition through the fuse.
3. 6. This step tests the ability of the PCM and the wiring to control the ground circuit.
4. 8. This step measures the resistance of the automatic transmission (AT) wiring harness assembly and the 2-3 SS valve.

Scheme 736

Scheme 737

Scheme 738

Scheme 739

The powertrain control module (PCM) monitors the engine speed, and the transmission output shaft speed. The PCM calculates turbine shaft speed and torque converter clutch (TCC) slip speed by using inputs from the automatic transmission input shaft speed sensor (AT ISS), the automatic transmission output shaft speed sensor (AT OSS), and other transmission components. The forward clutch housing is used as the ISS rotor. Whenever the TCC is engaged, engine speed and turbine speed will closely match, indicating low TCC slip speed. In D3 with the TCC engaged, calculated transmission component slip can only occur in the torque converter. In D4 OVERDRIVE with the TCC engaged, transmission component slip can occur in the TCC or the fourth clutch assembly.

If the PCM detects an excessive TCC slip speed in D4 OVERDRIVE, when the TCC should be engaged, then DTC P0894 sets. DTC P0894 is a type C DTC. For California emissions, DTC P0894 is a type B DTC.

1. No MAP sensor DTCs P0101, P0102 or P0103.
2. No MAF sensor DTCs P0106, P0107 or P0108.
3. No TP sensor DTCs P0121, P0122 or P0123.
4. No AT VSS DTC P0502, or P0503.
5. No AT ISS DTCs P0716 or P0717.
6. No TCC PWM solenoid valve DTCs P0741, P0742 or P1860.
7. No 1-2 SS valve DTCs P0751, P0752 or P0753.
8. No 2-3 SS valve DTCs P0756, P0757 or P0758.
9. The system voltage is 8-18 volts.
10. No TFP manual valve position switch DTCs P1810.
11. The TP sensor is 10-100 percent.
12. Engine speed is 1,250-5,000 RPM.
13. The TFT is 20-130°C (68-266°F).
14. Vehicle speed is 56-177 km/h (35-110 mph).
15. TFP manual valve position switch indicates D4.
16. Speed ratio is 2.25-0.70.
17. The engine torque must be between 108 N.m (80 lb ft) and: 4.8L: 542 N.m (400 lb ft) 6.0L: 576 N.m (425 lb ft)
18. The TCC is commanded ON for 0.04 second or more.
19. TCC is locked ON for greater than 0.1 second.
20. Commanded gear is 4th.

The PCM detects slip in the torque converter clutch and/or the fourth gear clutch pack with the TCC in an apply or locked mode. DTC P0894 sets during the second consecutive trip when one of the following condition occurs

1. The TCC slip speed is 100-550 for 10 seconds.
2. All conditions for running the DTC are met for three occurrences.

The following sequence of events occur

1. The TCC slip speed is 100-550 for 10 seconds, the PCM commands maximum line pressure.
2. The TCC slip speed is 100-550 for 12.5 seconds, the PCM commands the TCC Off for 2 seconds.
3. The TCC slip speed is 100-550 for 15.0 seconds.

Action Taken When the MIL/DTC Sets

1. For California emission equipped vehicles, the PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. For Federal emission equipped vehicles, the MIL is not illuminated.
2. The PCM commands maximum line capacity.
3. The PCM inhibits the TCC engagement.
4. The PCM freezes shift adapts.
5. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame, California only, and Failure Records, California and Federal.
6. The PCM stores the DTC P0894 in PCM history during the second consecutive trip, California, or the first trip, Federal, in which the Conditions for Setting the DTC are met.

1. For California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. For California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
4. For Federal emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
5. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

1. A TFP manual valve position switch malfunction can set DTC P0894.
2. A mechanical failure of the shift solenoids or TCC PWM solenoid valve can set DTC P0894.
3. Internal transmission failures can result in a DTC P0894.
4. Sticking or contaminated shift valves may cause intermittent slipping in D4.
5. DTC P0894 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine.

The numbers below refer to the step numbers on the diagnostic table.

1. 3. This step tests the indicated range signal to the actual selected range. A faulty TFP manual valve position switch can set a DTC P0894.
2. 4. This step tests for excessive TCC slip speed while in a commanded TCC lock-up state and in fourth gear; and confirms that the fault is present.
3. 5. This step tests for excessive TCC slip speed while in a commanded TCC lock-up state and in third gear.
4. 6. This step tests for a sticking TCC shift valve.
5. 7. This step tests for proper transmission line pressure.

Scheme 740

Scheme 741

Scheme 742

The automatic transmission fluid pressure (TFP) manual valve position switch consists of five normally open pressure switches. The powertrain control module (PCM) supplies battery voltage to each range signal. By grounding one or more of these circuits through various combinations of the pressure switches, the PCM detects what manual valve position has been selected, and compares the actual voltage combination of the switches to a TFP manual valve position switch combination table stored in memory.

The TFP manual valve position switch assembly cannot distinguish between PARK and NEUTRAL because the monitored valve body pressures are identical in both cases. With the ignition ON and the engine OFF, D2 is indicated. When the transmission 20-way connector is disconnected, the ground potential for the three range signals to the PCM is removed, and with the ignition ON, D2 is indicated.

If the PCM detects an invalid state of the TFP manual valve position switch circuit by deciphering the TFP manual valve position switch inputs, then DTC P1810 sets. DTC P1810 is a type C DTC. For California emissions vehicles DTC P1810 is a type B DTC.

1. No AT VSS DTCs P0502 or P0503.
2. No AT ISS DTCs P0716 or P0717.
3. No PSA DTC P1810.
4. No MAP DTCs P0106, P0107 or P0108.
5. No 1-2 SS DTCs P0751, P0752 or P0753.
6. No 2-3 SS DTCs P0756, P0757 or P0758.
7. No TP sensor DTCs P0121, P0122 or P0123.
8. The system voltage is 8-18 volts.
9. No MAF DTCs P0101, P0102 or P0103.

DTC P1810 sets on the first occurrence in which any of the following condition occurs

1. The engine speed is greater than 400 RPM for 7 seconds.
2. The PCM detects an illegal TFP manual valve position switch state for 60 seconds.

1. The engine speed is less than 50 RPM for 0.3 second; then 50-525 RPM for 0.025 second; then the engine speed is greater than 525 RPM.
2. The vehicle speed is less than 8 km/h (5 mph).
3. Engine RPM sequence must occur within 30 seconds of key on.
4. The PCM detects the gear range D2, D4 or REVERSE before and after start up.
5. All conditions are met for 7 seconds and AT ISS is greater than 200 RPM.

Condition 3

1. The vehicle speed is greater than 8 km/h (5 mph).
2. The TP angle is greater than 10 percent.
3. The PCM detects an invalid state of the PSA sensor or the PSA circuit.
4. The TFP switch indicates the following: P/N when the ratio indicates third or fourth gear for greater than 15 seconds. Reverse when the ratio indicates D4, D3, D2, and D1 for greater than 15 seconds. D4, D3, D2, and D1 when the ratio indicates reverse for greater than 7 seconds.
5. The engine torque must be between 108 N.m (80 lb ft) and: 4.8L: 542 N.m (400 lb ft) 6.0L: 576 N.m (425 lb ft)

1. For California emission equipped vehicles, the PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. For Federal emission equipped vehicles, the MIL is not illuminated.
2. The PCM commands maximum line pressure.
3. The PCM assumes D4 for the PRNDL shift pattern.
4. The PCM freezes shift adapts.
5. The PCM forces the TCC on in fourth gear.
6. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame, California only, and Failure Records, California and Federal.
7. The PCM stores the DTC P1810 in PCM history during the second consecutive trip, California, or the first trip, Federal, in which the Conditions for Setting the DTC are met.

1. For California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. For California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
4. For Federal emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
5. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

1. Refer to «Transmission Fluid Pressure (TFP) Manual Valve Position Switch Logic»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__transmission-fluid-pressure-tfp-manual-valve) for the normal range signals and the illegal combinations.
2. DTC P1810 can be set falsely by low pump pressure, a stuck pressure regulator, or unit fill from overhaul and pan removal.
3. DTC P1810 can be set by a slipping forward clutch. It may allow the PCM to see a 2.08:1 ratio, reverse, when the manual valve position is indicated as D4.
4. DTC P1810 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine.

The numbers below refer to the step numbers on the diagnostic table.

1. 3. This step tests the indicated range signal to the manual valve that is actually selected.
2. 5. This step tests the voltage from the PCM to the transmission AT inline 20-way connector.

Scheme 743

Scheme 744

Scheme 745

Scheme 746

The torque converter clutch pulse width modulation (TCC PWM) solenoid valve controls fluid acting on the converter clutch valve, which then controls TCC apply and release. The TCC PWM solenoid valve attaches to the control valve body within the transmission. Ignition voltage goes directly to the TCC PWM solenoid valve. The powertrain control module (PCM) controls the TCC PWM solenoid valve by providing a ground path on the control circuit. The current flows through the TCC PWM solenoid valve coil according to the duty cycle, percentage of ON time. The TCC PWM solenoid valve provides a smooth engagement of the torque converter clutch by operating on a duty cycle percent of ON time.

If the PCM detects a continuous open or short in the TCC PWM solenoid valve circuit or the TCC PWM solenoid valve, then DTC P1860 sets. DTC P1860 is a type C DTC. For California emission vehicles DTC P1860 is a type B DTC.

1. The system voltage is 8-18 volts.
2. The engine is running greater than 400 RPM for greater than 7 seconds.

All conditions for running the DTC are met, and either of the following conditions occur for 4.3 seconds out of 5 seconds

1. The PCM commands the TCC PWM solenoid valve to OFF, 0 percent, and the voltage input remains low, zero volts.
2. The PCM commands the TCC PWM solenoid valve to ON, 100 percent, and the voltage input remains high, B+.

1. For California emission equipped vehicles, the PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
2. The PCM inhibits TCC engagement.
3. The PCM commands increased line pressure.
4. The PCM freezes shift adapts from being updated.
5. The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame, California only, and Failure Records, California and Federal.
6. The PCM stores DTC P1860 in PCM history.

1. For California emissions, the PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
2. A scan tool can clear the MIL/DTC.
3. For California emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
4. For Federal emissions, the PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
5. The PCM cancels the DTC default actions when the fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

DTC P1860 defaults to an elevated line pressure condition which may result in partial TCC apply. This may produce an idle surge that could stall the engine.

The numbers below refer to the step numbers on the diagnostic table.

1. 4. This step tests for voltage to the solenoid.
2. 5. This step tests the ability of the PCM and wiring to control the ground circuit.
3. 7. This step tests the resistance of the TCC PWM solenoid valve and the automatic transmission wiring harness assembly.

Scheme 747

Scheme 748

Scheme 749

Scheme 750

Scheme 751

Scheme 752

Scheme 753

The transmission range (TR) switch is part of the park/neutral position (PNP) and back-up lamp switch assembly, which is externally mounted on the transmission manual shaft. The TR switch contains four internal switches that indicate the transmission gear range selector lever position. The PCM supplies ignition voltage to each switch circuit. As the gear range selector lever is moved, the state of each switch may change, causing the circuit to open or close. An open circuit or switch indicates a high voltage signal. A closed circuit or switch indicates a low voltage signal. The PCM detects the selected gear range by deciphering the combination of the voltage signals. The PCM compares the actual voltage combination of the switch signals to a TR switch combination chart stored in memory.

Refer to Transmission Range Switch Logic for valid combinations of switch signal circuits A, B, C and Parity. On the table, HI indicates an ignition voltage signal. LOW indicates a zero voltage signal.

The numbers below refer to the step numbers on the diagnostic table.

1. 4. By disconnecting the TR switch, the ground path of all TR switch circuits would be removed and the PCM should recognize all circuits as open. The scan tool should display HI for all range signal states.
2. 6. This step tests the TR switch wiring for an open or the lack of the signal voltage from the PCM.
3. 7. This step tests the TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the scan tool range signal states should change to LOW.
4. 8. This step tests the TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the scan tool range signal states should change to LOW.
5. 9. This step tests the TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the scan tool range signal states should change to LOW.
6. 10. This step tests the TR switch wiring and the PCM by providing a ground path through a fused jumper wire. When grounded, the scan tool range signal states should change to LOW.

Scheme 754

Scheme 755

Scheme 756

Tow/haul mode enables the operator to achieve enhanced shift performance when towing or hauling a load. When tow/haul mode is selected, the tow/haul switch input signal to the body control module (BCM) is momentarily toggled to zero volts. This signals the powertrain control module (PCM) to extend the length of time between upshifts and increase transmission line pressure. Cycling the tow/haul switch again disables tow/haul mode and returns the transmission to a normal shift pattern.

If the electrical circuit checks are OK and the tow/haul shift pattern is not occurring, there may be a mechanical/hydraulic condition that prevents tow/haul operation. Refer to Symptoms - Automatic Transmission .

The numbers below refer to the step numbers on the diagnostic table.

1. 2. This step tests for a faulty tow/haul switch.
2. 3. This step tests for voltage input from the BCM to the tow/haul switch.
3. 6. This step tests for ground integrity.

Scheme 757

Transmission Fluid Checking Procedure

1. Start the engine and operate the vehicle for 15 minutes or until the transmission fluid reaches an operating temperature of 82-93°C (180-200° F).
2. Park the vehicle on a level surface.
3. With your foot on the brake, move the shift lever through each gear range. Pause for about three seconds in each range, ending in Park.
4. Apply the parking brake and let the engine idle for 3 minutes.
5. Remove the transmission fluid level indicator. Wipe the indicator clean. Insert the indicator. Give the indicator a full twist in order to close.
6. Wait 3 seconds and remove the indicator.
7. Read both sides of the indicator. The fluid must be within the hot cross-hatched area using the lowest level reading.

Scheme 758

Scheme 759

Line Pressure Check Procedure

Tools Required

J 21867 Pressure Gage

Line pressures are calibrated for two sets of gear ranges - Drive, Park, Neutral, and Reverse. This allows the transmission line pressure to be appropriate for different pressure needs in different gear ranges

Line Pressure Check

Before performing a line pressure check, verify that the pressure control solenoid for the transmission is receiving the correct electrical signal from the vehicle computer

Scheme 760

1. Install a scan tool. WARNING: Keep the brakes applied at all times in order to prevent unexpected vehicle motion. Personal injury may result if the vehicle moves unexpectedly. Important: The transmission may experience harsh, soft or mushy shifts for up to two days later.
2. Start the engine and set the parking brake.
3. Check for diagnostic trouble codes, including the diagnostic code for a pressure control solenoid.
4. Repair the vehicle if necessary. Include the following areas: Inspect the fluid level. Inspect the manual linkage at the transmission. Install or connect the scan tool. Install or connect the J 21867 at the line pressure tap.
5. Put the gear selector in PARK and set the parking brake.
6. Start the engine and allow the engine to warm up at idle.
7. Access the Override Pressure Control Solenoid test on the scan tool.
8. Increase the Pressure Control Solenoid Current in 0.1 amp increments. Read the corresponding line pressure on the J 21867 . Allow the pressure to stabilize for 5 seconds after each current change.
9. Compare your data to the Drive-Park-Neutral «Line Pressure»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__line-pressure) .
10. Remove the J 21867 . Important: Be sure to apply pipe thread sealant with Teflon GM P/N 12346004 (Canadian P/N 10953480) to the line pressure plug.
11. Install the line pressure tap plug. If your pressure readings differ greatly from the line pressure table, refer to the Diagnostic Tables. The scan tool is only able to control the pressure control solenoid in PARK and NEUTRAL with the vehicle stopped at idle. This protects the clutches from extremely high or low pressures in DRIVE or REVERSE ranges.

Road Test Procedure

The following test provides a method of evaluating the condition of the automatic transmission. The test is structured so that most driving conditions would be achieved. The test is divided into the following parts

1. Electrical Function Check
2. Upshift Control and Torque Converter Clutch (TCC) Apply
3. Part Throttle Detent Downshifts
4. Full Throttle Detent Downshifts
5. Manual Downshifts
6. Coasting Downshifts
7. Manual Gear Range Selection REVERSE Manual FIRST Manual SECOND Manual THIRD

Important: Complete the test in the sequence given. Incomplete testing cannot guarantee an accurate evaluation.

Before the road test, ensure the following

1. The engine is performing properly.
2. Transmission fluid level is correct.
3. Tire pressure is correct.

During the road test

1. Perform the test only when traffic conditions permit.
2. Operate the vehicle in a controlled, safe manner.
3. Observe all traffic regulations.
4. View the scan tool data while conducting this test. Take along qualified help in order to operate the vehicle safely.
5. Observe any unusual sounds or smells.

After the road test, check the following

1. Transmission fluid level. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__transmission-fluid-checking-procedure) .
2. Diagnostic Trouble Codes (DTCs) that may have set during the testing. Refer to the applicable DTC.
3. Scan tool data for any abnormal readings or data.

Electrical Function Check

Perform this check first, in order to ensure the electronic transmission components are connected and functioning properly. If these components are not checked, a simple electrical condition could be mis-diagnosed.

1. Connect the scan tool.
2. Ensure the gear selector is in PARK and set the parking brake.
3. Start the engine.
4. Verify that the following scan tool data can be obtained and is functioning properly. Refer to «Transmission Scan Tool Data List»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__transmission-scan-tool-data-list) for typical data values. Data that is questionable may indicate a concern. Engine speed Transmission input speed, turbine Transmission output speed Vehicle speed TFP manual valve position switch Transmission range, engine list 4WD low Commanded gear PC solenoid reference current PC solenoid actual current PC solenoid duty cycle Brake switch Engine coolant temperature Transmission fluid temperature Throttle angle Ignition voltage 1-2 shift solenoid 2-3 shift solenoid TCC solenoid duty cycle TCC slip speed
5. Monitor the brake switch signal while depressing and releasing the brake pedal. The scan tool should display: Closed when the brake pedal is released Open when the brake pedal is depressed
6. Check the garage shifts Apply the brake pedal and ensure the parking brake is set. Move the gear selector through the following ranges: PARK to REVERSE REVERSE to NEUTRAL NEUTRAL to DRIVE Pause 2-3 seconds in each gear position. Verify the gear engagements are immediate and not harsh. Important: Harsh engagement may be caused by any of the following conditions: High idle speed Compare engine idle speed to desired idle speed. Commanded low PC solenoid current Compare PC solenoid reference current to PC solenoid actual current. A default condition caused by certain DTCs that result in maximum line pressure to prevent slippage Important: Soft or delayed engagement may be caused by any of the following conditions: Low idle speed Compare engine idle speed to desired idle speed. Low fluid level Commanded high PC solenoid current Compare PC solenoid reference current to PC solenoid actual current. Cold transmission fluid Check for low transmission fluid temperature.
7. Monitor transmission range on the scan tool, engine list. Apply the brake pedal and ensure the parking brake is set. Move the gear selector through all ranges. Pause 2-3 seconds in each range. Return gear selector to PARK. Verify that all selector positions match the scan tool display.
8. Check throttle angle input. Apply the brake pedal and ensure the parking brake is set. Ensure the gear selector is in PARK. Monitor throttle angle while increasing and decreasing engine speed with the throttle pedal. The scan tool throttle angle should increase and decrease with engine speed. If any of the above checks do not perform properly, record the result for reference after completion of the road test.

Upshift Control and Torque Converter Clutch (TCC) Apply

The PCM calculates the upshift points based primarily on two inputs: throttle angle and vehicle speed. When the PCM determines that conditions are met for a shift to occur, the PCM commands the shift by closing or opening the ground circuit for the appropriate solenoid.

Perform the following steps

1. Refer to «Shift Speed»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) and choose a throttle position of 10 percent, 25 percent or 50 percent. All throttle angles shown should be tested to cover the normal driving range.
2. Monitor the following scan tool parameters: Throttle angle Vehicle speed t. Engine speed Output shaft speed Commanded gear Slip speed Solenoid states
3. Place the gear selector in the OVERDRIVE position.
4. Accelerate the vehicle using the chosen throttle angle. Hold the throttle steady.
5. As the transmission upshifts, note the vehicle speed when the shift occurs for each gear change. There should be a noticeable shift feel or engine speed change within 1-2 seconds of the commanded gear change.
6. Compare the shift speeds to the Shift Speed table. Refer to «Shift Speed»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) Shift speeds may vary slightly due to transmission fluid temperature or hydraulic delays in responding to electronic controls. Note any harsh, soft or delayed shifts or slipping. Note any noise or vibration.
7. Repeat steps 1-6 to complete all throttle angles. Important: The TCC will not engage until the engine is in closed loop operation. The vehicle must be in a near-cruise condition, not accelerating or coasting, and on a level road surface.
8. Check for TCC apply in THIRD and FOURTH gear. Typical apply speeds in FOURTH gear range from 72-88 km/h (45-55 mph) depending on engine size, engine type and axle ratio. Note the TCC apply point. When the TCC applies there should be a noticeable drop in engine speed and a drop in slip speed to below 100 RPM. If the TCC apply can not be detected: Check for DTCs. Refer to «Torque Converter Diagnosis Procedure»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__torque-converter-diagnosis-procedure) . Lightly tap and release the brake pedal. The TCC will release.

Part Throttle Detent Downshift

1. Place the gear selector in the OVERDRIVE position.
2. Accelerate the vehicle to 64-88 km/h (40-55 mph) in FOURTH gear.
3. Quickly increase throttle angle to greater than 50 percent.
4. Verify the following: The TCC releases The transmission downshifts immediately to THIRD gear

Full Throttle Detent Downshift

1. Place the gear selector in the OVERDRIVE position.
2. Accelerate the vehicle to speeds of 64-88 km/h (40-55 mph) in FOURTH gear.
3. Quickly increase throttle angle to 100 percent (WOT).
4. Verify the following: The TCC releases The transmission downshifts immediately to SECOND gear

Manual Downshifts

The shift solenoid valves do not control manual downshifts. All manual downshifts are hydraulic. The solenoid states will change during, or shortly after, a manual downshift is selected.

Manual 4-3 Downshift

1. Place the gear selector in the OVERDRIVE position.
2. Accelerate the vehicle to 64-88 km/h (40-55 mph) in FOURTH gear.
3. Release the throttle while moving the gear selector to THIRD.
4. Verify the following: The transmission downshifts immediately to THIRD gear The engine slows the vehicle

Manual 4-2 Downshift

1. Place the gear selector in the OVERDRIVE position.
2. Accelerate the vehicle to 64-72 km/h (40-45 mph).
3. Release the throttle while moving the gear selector to SECOND.
4. Verify the following: The TGC releases The transmission downshifts immediately to SECOND gear The engine slows the vehicle

Manual 4-1 Downshift

1. Place the gear selector in the OVERDRIVE position.
2. Accelerate the vehicle to 64 km/h (40 mph).
3. Release the throttle while moving the gear selector to FIRST.
4. Verify the following: The TCC releases The transmission immediately downshifts to FIRST Gear. The engine slows the vehicle.

Coasting Downshifts

1. Place the gear selector in the OVERDRIVE position.
2. Accelerate the vehicle to FOURTH gear with the TCC applied.
3. Release the throttle and lightly apply the brakes.
4. Verify the following: The TCC releases Downshifts occur at speeds shown in the Shift Speed table. Refer to «Shift Speed»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .

Manual Gear Range Selection

The shift solenoids control the upshifts in the manual gear ranges.

Perform the following tests using 10 percent to 15 percent throttle angle.

Reverse

1. With the vehicle stopped, move the gear selector to REVERSE.
2. Slowly accelerate the vehicle.
3. Verify that there is no noticeable slip, noise or vibration.

Manual First

1. With the vehicle stopped, move the gear selector to FIRST.
2. Accelerate the vehicle to 32 km/h (20 mph).
3. Verify the following: No upshifts occur. The TCC does not apply. There is no noticeable slip, noise, or vibration.

Manual Second

1. With the vehicle stopped, move the gear selector to SECOND.
2. Accelerate the vehicle to 57 km/h (35 mph).
3. Verify the following: The 1-2 shift occurs. The 2-3 shift does not occur. There is no noticeable slip, noise, or vibration.

Manual Third

1. With the vehicle stopped, move the gear selector to THIRD.
2. Accelerate the vehicle to 64 km/h (40 mph).
3. Verify the following: The 1-2 shift occurs. The 2-3 shift occurs. There is no noticeable slip, noise, or vibration.

Torque Converter Diagnosis Procedure

The Torque Converter Clutch (TCC) is applied by fluid pressure, which is controlled by a PWM solenoid valve. This solenoid valve is located inside of the automatic transmission assembly. The solenoid valve is controlled through a combination of computer controlled switches and sensors.

Torque Converter Stator

The torque converter stator roller clutch can have two different malfunctions.

1. The stator assembly freewheels in both directions.
2. The stator assembly remains locked up at all times.

Poor Acceleration at Low Speed

If the stator is freewheeling at all times, the vehicle tends to have poor acceleration from a standstill. At speeds above 50-55 km/h (30-35 mph), the vehicle may act normally. For poor acceleration, you should first determine that the exhaust system is not blocked, and the transmission is in First gear when starting out.

If the engine freely accelerates to high RPM in NEUTRAL, you can assume that the engine and the exhaust system are normal. Check for poor performance in DRIVE and REVERSE to help determine if the stator is freewheeling at all times.

Poor Acceleration at High Speed

If the stator is locked up at all times, performance is normal when accelerating from a standstill. Engine RPM and vehicle speed are limited or restricted at high speeds. Visual examination of the converter may reveal a blue color from overheating.

If the converter has been removed, you can inspect the stator roller clutch by inserting a finger into the splined inner race of the roller clutch and trying to turn the race in both directions. You should be able to freely turn the inner race clockwise, but you should have difficulty in moving the inner race counterclockwise or you may be unable to move the race at all.

Whine Noise

Important: Do not confuse this noise with pump whine noise, which is usually noticeable in PARK, NEUTRAL and all other gear ranges. Pump whine will vary with line pressure.

You may notice a torque converter whine when the vehicle is stopped and the transmission is in DRIVE or REVERSE. This noise will increase as you increase the engine RPM. The noise will stop when the vehicle is moving or when you apply the torque converter clutch, because both halves of the converter are turning at the same speed.

Perform a stall test to make sure the noise is actually coming from the converter

1. Place your foot on the brake.
2. Put the gear selector in DRIVE. CAUTION: You may damage the transmission if you depress the accelerator for more than 6 seconds.
3. Depress the accelerator to approximately 1,200 RPM for no more than six seconds.

A torque converter noise will increase under this load.

Torque Converter Clutch Shudder

The key to diagnosing Torque Converter Clutch (TCC) shudder is to note when it happens and under what conditions.

TCC shudder which is caused by the transmission should only occur during the apply or the release of the converter clutch. Shudder should never occur after the TCC plate is fully applied.

If the shudder occurs while the TCC is applying, the problem can be within the transmission or the torque converter. Something is causing one of the following conditions to occur

1. Something is not allowing the clutch to become fully engaged.
2. Something is not allowing the clutch to release.
3. The clutch is releasing and applying at the same time.

One of the following conditions may be causing the condition to occur

1. Leaking turbine shaft seals
2. A restricted release orifice
3. A distorted clutch or housing surface due to long converter bolts
4. Defective friction material on the TCC plate

If Shudder Occurs After TCC has Applied

Important: If shudder occurs after the TCC has applied, most of the time there is nothing wrong with the transmission.

As mentioned above, the TCC is not likely to slip after the TCC has been applied. Engine problems may go unnoticed under light throttle and load, but they become noticeable after the TCC apply when going up a hill or accelerating. This is due to the mechanical coupling between the engine and the transmission.

Once TCC is applied, there is no torque converter, fluid coupling, assistance. Engine or driveline vibrations could be unnoticeable before TCC engagement.

Inspect the following components in order to avoid misdiagnosis of TCC shudder. An inspection will also avoid the unnecessary disassembly of a transmission, or the unnecessary replacement of a torque converter.

1. Spark plugs Inspect for cracks, high resistance or a broken insulator.
2. Plug wires Look in each end. If there is red dust, ozone, or a black substance, carbon, present, the wires are bad. Also look for a white discoloration of the wire. This indicates arcing during hard acceleration.
3. Coil Look for a black discoloration on the bottom of the coil. This indicates arcing while the engine is misfiring.
4. Fuel injector The filter may be plugged.
5. Vacuum leak The engine will not get a correct amount of fuel. The mixture may run rich or lean depending on where the leak occurs.
6. EGR valve The valve may let in too much or too little unburnable exhaust gas and could cause the engine to run rich or lean.
7. MAP/MAF sensor Like a vacuum leak, the engine will not get the correct amount of fuel for proper engine operation.
8. Carbon on the intake valves Carbon restricts the proper flow of air/fuel mixture into the cylinders.
9. Flat cam Valves do not open enough to let the proper fuel/air mixture into the cylinders.
10. Oxygen sensor This sensor may command the engine too rich or too lean for too long.
11. Fuel pressure This may be too low.
12. Engine mounts Vibration of the mounts can be multiplied by TCC engagement.
13. Axle joints Check for vibration.
14. TP Sensor The TCC apply and release depends on the TP sensor in many engines. If the TP sensor is out of specification, TCC may remain applied during initial engine loading.
15. Cylinder balance Bad piston rings or poorly sealing valves can cause low power in a cylinder.
16. Fuel contamination This causes poor engine performance.

Torque Converter Evaluation and Diagnosis

Replace the torque converter if any of the following conditions exist

1. External leaks appear in the hub weld area.
2. The converter hub is scored or damaged.
3. The converter pilot is broken, damaged, or fits poorly into the crankshaft.
4. You discover steel particles after flushing the cooler and the cooler lines.
5. The pump is damaged, or you discover steel particles in the converter.
6. The vehicle has TCC shudder and/or no TCC apply. Replace the torque converter only after all hydraulic and electrical diagnoses have been made. The converter clutch material may be glazed.
7. The converter has an imbalance which cannot be corrected. Refer to «Flexplate/Torque Converter Vibration Test»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__flexplatetorque-converter-vibration-test) .
8. The converter is contaminated with engine coolant which contains antifreeze.
9. An internal failure occurs in the stator roller clutch.
10. You notice excessive end play.
11. Overheating produces heavy debris in the clutch.
12. You discover steel particles or clutch lining material in the fluid filter or on the magnet, when no internal parts in the unit are worn or damaged. This condition indicates that lining material came from the converter.

Do Not Replace the Torque Converter if you discover any of the following symptoms

1. The oil has an odor or the oil is discolored, even though metal or clutch facing particles are not present.
2. The threads in one or more of the converter bolt holds are damaged. Correct the condition with a new thread insert.
3. Transmission failure did not display evidence of damaged or worn internal parts, steel particles or clutch plate lining material in the unit and inside the fluid filter.
4. The vehicle has been exposed to high mileage only. An exception may exist where the lining of the torque converter clutch dampener plate has seen excess wear by vehicles operated in heavy and/or constant traffic, such as taxi, delivery, or police use.

Flexplate/Torque Converter Vibration Test

Isolating Vibration

To isolate and correct a flywheel or torque converter vibration, separate the torque converter from the flywheel to determine if vibration is in the engine or transmission.

1. With the engine at idle speed and the transmission in PARK or NEUTRAL, observe the vibration.
2. Turn the engine OFF.
3. Raise and suitably support the vehicle.
4. Remove the transmission converter cover bolts and the cover.
5. Mark the relationship of the converter to the flywheel.
6. Remove the bolts attaching the converter to the flywheel.
7. Slide the torque converter away from the flywheel.
8. Rotate the flywheel and torque converter to inspect for defects or missing balance weights. Refer to «ENGINE FLYWHEEL CLEANING AND INSPECTION»(/chevrolet/chevy-express-h2500/2003-2003/remont/mechanical/#engine-mechanical-48l-53l-60l) .
9. Lower the vehicle.
10. With the engine at idle speed and the transmission in PARK or NEUTRAL, observe the vibration.
11. Turn the engine OFF.

Indexing Torque Converter

To determine and correct a torque converter vibration, the following procedure may have to be performed several times to achieve the best possible torque converter to flywheel balance.

Scheme 761

1. Raise and suitably support the vehicle.
2. Rotate the torque converter one bolt position.
3. Align the torque converter hub (2) in the engine crankshaft (3) and install the torque converter to flywheel bolts.
4. Lower the vehicle.
5. With the engine at idle speed and the transmission in PARK or NEUTRAL, observe the vibration. Refer to «Noise and Vibration Analysis»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__noise-and-vibration-analysis) . Repeat this procedure until you obtain the best possible balance.
6. Install the transmission converter cover bolts and the cover.

Noise and Vibration Analysis

A noise or vibration that is noticeable when the vehicle is in motion MAY NOT be the result of the transmission.

If noise or vibration is noticeable in PARK and NEUTRAL with the engine at idle, but is less noticeable as RPM increases, the cause may be from poor engine performance.

1. Inspect the tire for the following: Uneven wear Imbalance Mixed sizes Mixed radial and bias ply
2. Inspect the suspension components for the following: Alignment and wear Loose fasteners
3. Inspect the engine and transmission mounts for damage and loose bolts.
4. Inspect the transmission case mounting holes for the following: Missing bolts, nuts, and studs Stripped threads Cracks
5. Inspect the flywheel for the following: Missing or loose bolts Cracks Imbalance
6. Inspect the torque converter for the following: Missing or loose bolts or lugs Missing or loose balance weights Imbalance

Composition Plates

Dry the plates and inspect the plates for the following conditions

1. Pitting
2. Flaking
3. Wear
4. Glazing
5. Cracking
6. Charring
7. Chips or metal particles embedded in the lining

Replace a composition plate which shows any of these conditions.

Steel Plates

Wipe the plates dry and check the plates for heat discoloration. If the surfaces are smooth, even if color smear is indicated/you can reuse the plate. If the plate is discolored with heat spots or if the surface is scuffed, replace the plate.

Causes of Burned Clutch Plates

The following conditions can result in a burned clutch plate

1. Incorrect usage of clutch plates
2. Engine coolant in the transmission fluid
3. A cracked clutch piston
4. Damaged or missing seals
5. Low line pressure
6. Valve body conditions The valve body face is not flat. Porosity is between channels. The valve bushing clips are improperly installed. The checkballs are misplaced.
7. The Teflon® seal rings are worn or damaged.

Engine Coolant in Transmission

If the transmission oil cooler has developed a leak allowing engine coolant to enter the transmission, perform the following

1. Disassemble the transmission.
2. Replace all of the rubber type seals. The coolant will attack the seal material which will cause leakage.
3. Replace the composition-faced clutch plate assemblies. The facing material may separate from the steel center portion.
4. Replace all of the nylon parts - washers.
5. Replace the torque converter.
6. Thoroughly clean and rebuild the transmission, using new gaskets and oil filter.
7. Flush the cooler lines after the transmission cooler has been properly repaired or replaced.

General Method

1. Verify that the leak is transmission fluid.
2. Thoroughly clean the suspected leak area.
3. Operate the vehicle for 24 km (15 mi), or until normal operating temperatures are reached.
4. Park the vehicle over clean paper or cardboard.
5. Shut OFF the engine.
6. Look for fluid spots on the paper.
7. Make the necessary repairs.

Powder Method

1. Thoroughly clean the suspected leak area with solvent.
2. Apply an aerosol type powder, such as foot powder, to the suspected leak area.
3. Operate the vehicle for 24 km (15 mi), or until normal operating temperatures are reached.
4. Shut OFF the engine.
5. Inspect the suspected leak area.
6. Trace the leak path through the powder in order to find the source of the leak.
7. Make the necessary repairs.

Dye and Black Light Method

A fluid dye and black light kit is available from various tool manufacturers.

1. Follow the manufacturer's instructions in order to determine the amount of dye to use.
2. Detect the leak with the black light.
3. Make the necessary repairs.

Find the Cause of the Leak

Pinpoint the leak and trace the leak back to the source. You must determine the cause of the leak in order to repair the leak properly. For example, if you replace a gasket, but the sealing flange is bent, the new gasket will not repair the leak. You must also repair the bent flange. Before you attempt to repair a leak, check for the following conditions, and make repairs as necessary

Gaskets

1. Fluid level/pressure is too high
2. Plugged vent or drain-back holes
3. Improperly tightened fasteners
4. Dirty or damaged threads
5. Warped flanges or sealing surface
6. Scratches, burrs, or other damage to the sealing surface
7. Damaged or worn gasket
8. Cracking or porosity of the component
9. Improper sealant used, where applicable
10. Incorrect gasket

Seals

1. Fluid level/pressure is too high
2. Plugged vent or drain-back holes
3. Damaged seal bore
4. Damaged or worn seal
5. Improper installation
6. Cracks in component
7. Manual or output shaft surface is scratched, nicked, or damaged
8. Loose or worn bearing causing excess seal wear

Transmission Oil Pan

1. Incorrectly tightened oil pan bolts
2. Improperly installed or damaged oil pan gasket
3. Damaged oil pan or mounting face
4. Incorrect oil pan gasket

Case Leak

1. Damaged or missing fill tube seal
2. Mislocated fill tube bracket
3. Damaged vehicle speed sensor seal
4. Damaged manual shaft seal
5. Loose or damaged oil cooler connector fittings
6. Worn or damaged propeller shaft oil seal
7. Loose line pressure pipe plug
8. Porous casting

Leak at the Torque Converter End

1. Converter leak in the weld area
2. Converter seal lip cut. Check the converter hub for damage
3. Converter seal bushing moved forward and damaged
4. Converter seal garter spring missing from the seal
5. Porous casting of the transmission case or the oil pump

Leak at the Vent Pipe or the Fluid Fill Tube

1. Overfilled system
2. Water or coolant in the fluid. The fluid will appear milky
3. Transmission case porous
4. Incorrect fluid level indicator
5. Plugged vent
6. Drain-back holes plugged
7. Mispositioned oil pump to case gasket, if equipped

Scheme 762

Case Porosity Repair

Some external leaks are caused by case porosity in non-pressurized areas. You can usually repair these leaks with the transmission in the car.

1. Thoroughly clean the area to be repaired with a cleaning solvent. Air dry the area. WARNING: Epoxy adhesive may cause skin irritations and eye damage. Read and follow all information on the container label as provided by the manufacturer.
2. Using instructions from the manufacturer, mix a sufficient amount of an epoxy to make the repair.
3. While the transmission case is still hot, apply the epoxy. You can use a clean, dry soldering acid brush to clean the area and also to apply the epoxy cement. Make certain that the area to be repaired is fully covered.
4. Allow the epoxy cement to cure for three hours before starting the engine.
5. Repeat the fluid leak diagnosis procedures.

Shift Solenoid Leak Test

Tools Required

J 44246 Solenoid Testing Kit

Important

1. This procedure tests On/Off type solenoid valves.
2. Visually inspect the physical condition of the solenoid before testing. Inspect the O-rings before and after the test to be sure that they are not cut or damaged.

Scheme 763

Scheme 764

1. Remove the solenoid from the control valve body. Refer to «Valve Body and Pressure Switch Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__valve-body-and-pressure-switch-replacement) .
2. Install the 1-2 shift solenoid valve or the 2-3 shift solenoid valve into bore number 1 of the J 44246 and install the factory bolt to retain the solenoid.
3. Connect the solenoid testing harness supplied with the J 44246 to the solenoid. Important: Do not use air pressure in excess of 120 psi. Excessive pressure will not allow the solenoid ball check valve to seat properly. Recommended air pressure is 50 psi.
4. Apply compressed air to the J 44246 .
5. Air should flow through the solenoid. If air does not flow through the solenoid, replace the solenoid. Refer to «Valve Body and Pressure Switch Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__valve-body-and-pressure-switch-replacement) .
6. Connect the solenoid testing harness to the 12 volt positive and negative (-) battery terminals.
7. Observe if the solenoid is operating electrically. An audible clicking noise can be heard when connecting or disconnecting power. Important: All solenoids need to be energized to seal. A small amount of air leakage is normal +/-21 kPa (+/-3 psi).
8. Observe the air flow through the solenoid. The flow will completely or nearly completely stop. Replace the solenoid if there continues to be an obvious air leak when the solenoid is energized. Important: Inspect the O-rings after the test to be sure that they are not cut or damaged.
9. Install the solenoid into the control valve body. Refer to «Valve Body and Pressure Switch Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__valve-body-and-pressure-switch-replacement) .

Automatic Transmission Oil Cooler Flushing and Flow Test (J 35944-A)

GM studies indicate that plugged or restricted transmission oil coolers and pipes cause insufficient transmission lubrication and elevated operating temperatures which can lead to premature transmission wear-out. Many repeat repair cases could have been prevented by following published procedures for transmission oil cooler flushing and flow checking. This procedure includes flow checking and flushing the auxiliary transmission oil cooler, if equipped.

Important: Use the J 35944-A or equivalent to flush the transmission oil cooler and the oil cooler pipes whenever the transaxle is removed for the following repairs

1. Torque converter
2. Oil pump
3. Oil pump drive shaft
4. Drive sprocket support
5. Transaxle overhaul complete
6. Transaxle assembly replacement

Important: Use the J 35944-A or equivalent to flush the transmission oil cooler and the oil cooler pipes whenever the transmission is removed for the following repairs

1. Torque converter
2. Oil pump
3. Turbine shaft
4. Transmission overhaul complete
5. Transmission assembly replacement

Only GM Goodwrench DEXRON®III automatic transmission fluid should be used when doing a repair on a GM transmission.

Time allowance for performing the cooler flow checking and flushing procedure has been included in the appropriate labor time guide operations since the 1987 model year. The service procedure steps for oil cooler flushing are as follows

Cooler Flow Check and Flushing Steps

1. Tools Required
2. Preparation
3. Back Flush
4. Forward Flush
5. Flow Check
6. Clean-up

Tools Required

1. J 35944-A Transmission Oil Cooler and Line Flusher
2. J 35944-22 Transmission Oil Cooler Flushing Fluid
3. J 35944-200 Cooler Flushing Adapter
4. Measuring cup
5. Funnel
6. Water supply - hot water recommended
7. Water hose, at least 16 mm (5/8 in) ID
8. Shop air supply with water/oil filters, regulator and pressure gage
9. Air chuck with clip, if available
10. Oil drain container
11. Pail with lid - 19 L (5 gallon)
12. Eye protection
13. Rubber gloves

Preparation

1. During the installation of the repaired or replacement transmission, do not connect the oil cooler pipes. CAUTION: Do not use solutions that contain alcohol or glycol. Use of solutions that contain alcohol or glycol may damage the J 35944-A , oil cooler components and/or transmission components. Important: The J 35944-22 is environmentally safe, yet powerful enough to cut through transmission fluid to dislodge any contaminants from the cooler. The safety precautions on the label, regarding potential skin and eye irritations associated with prolonged exposure, are typical precautions that apply to many similar cleaning solutions. It should be noted that according to GM, use of other non-approved fluids for cooler flushing can have an adverse reaction to the seals inside the transmission.
2. Remove the fill cap (9) on the J 35944-A and fill the flusher tank (4) with 0.6 L (20-21 oz) of J 35944-22 , using the measuring cup (6). Do not overfill.
3. Install the fill cap (9) on the J 35944-A and pressurize the flusher tank (4) to 550-700 kPa (80-100 psi), using the shop air supply at the tank air valve (2).
4. With the water supply valve (1) on the J 35944-A in the OFF position, connect the water supply hose from the J 35944-A to the water supply at the faucet.
5. Turn ON the water supply at the faucet.

Scheme 765

1. Inspect the transmission oil cooler pipes for kinks or damage. Repair as necessary.
2. Connect the J 35944-A to the oil cooler feed front connector. Use the J 35944-200 , if required.
3. Clip the discharge hose (2) onto the oil drain container.
4. Attach the J 35944-A to the undercarriage of the vehicle with the hook provided and connect the flushing system feed supply hose (1) from the J 35944-A to the rear connector oil cooler return pipe. Use the J 35944-200 , if required.
5. Turn the J 35944-A water supply valve (3) to the ON position and allow water to flow through the oil cooler and pipes for 10 seconds to remove any remaining transmission fluid. If water does not flow through the oil cooler and pipes, the cause of the blockage must be diagnosed and the plugged component must be repaired or replaced. Continue with the cooler flushing and flow check procedure once the blockage is corrected.
6. Turn the J 35944-A water supply valve (3) to the OFF position and clip the discharge hose onto a 19 liter (5 gallon) pail with a lid, to avoid splashback. Important: Flushing for approximately 2 minutes in each cooler line direction will result in a total of about 8-10 gallons of waste fluid. This mixture of water and flushing fluid is to be captured in a bucket or similar container.
7. Turn the J 35944-A water supply valve (3) to the ON position and depress the trigger (1) to mix cooler flushing solution into the water flow. Use the clip provided on the handle to hold the trigger (1) down. The discharge will foam vigorously when the solution is introduced into the water stream.
8. Flush the oil cooler and pipes with water and solution for 2 minutes. During this flush, attach the shop air supply 825 kPa (120 psi) to the flushing system feed air valve (2) located on the J 35944-A , for 3-5 seconds at the end of every 15-20 second interval to create a surging action.
9. Release the trigger (1) and turn the J 35944-A water supply valve (3) to the OFF position.

Scheme 766

1. Disconnect both hoses (1 and 2) from the oil cooler pipes and connect them to the opposite oil cooler pipe. This will allow the oil cooler and pipes to be flushed in the normal flow direction.
2. Repeat Step 6 and 7 of the Back Flush.
3. Release the trigger (1) of the J 35944-A and allow water only to rinse the oil cooler and pipes for 1 minute.
4. Turn the J 35944-A water supply valve (3) to the OFF position and turn OFF the water supply at the faucet.
5. Attach the shop air supply to the flushing system feed air valve (2) on the J 35944-A and blow out the water from the oil cooler and pipes. Continue, until no water comes out of the discharge hose.

Flow Test

Important: The Flow Test must be performed after the flush to ensure that all flushing solution and water is removed from the oil cooling system.

Scheme 767

1. Disconnect the hose from the oil cooler pipe. Connect the oil cooler feed pipe, front connector, to the transmission for normal flow.
2. Clip the discharge hose (1) to an empty oil container.
3. Confirm the transmission is filled with automatic transmission fluid. Refer to «Fluid Capacity Specifications»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__fluid-capacity-specifications) for the correct automatic transmission fluid capacity.
4. Start the engine with the transmission in PARK range and run for 30 seconds after fluid begins to flow from the discharge hose (1). A minimum of 1.9 L (2 quarts) must be discharged during this 30 second run time.
5. If the fluid flow meets or exceeds 1.9 L (2 quarts) in 30 seconds, connect the oil cooler feed pipe to the front connector on the transmission.
6. If fluid flow is less than 1.9 L (2 qt) in 30 seconds, perform the following diagnosis: Disconnect the J 35944-A discharge hose (1) from the oil cooler return pipe. Disconnect the oil cooler feed pipe at the radiator. Connect the J 35944-A discharge hose (1) to the oil cooler feed pipe, radiator end. Clip the discharge hose (1) onto the oil drain container. Start the engine with the transmission in PARK range and run for 30 seconds after fluid begins to flow from the discharge hose (1). A minimum of 1.9 L (2 qt) must be discharged during this 30 second run time.
7. If the amount of transmission fluid flow remains less than 1.9 L (2 qt) in 30 seconds, inspect the oil cooler feed pipe, front connector, for restrictions or damage. If no condition is found with the feed pipe, front connector, inspect the transmission.

Clean-up

1. Disconnect the water supply hose from the J 35944-A and bleed any remaining air pressure from the flusher tank.
2. Remove the fill cap from the J 35944-A and return any unused flushing solution to its container. Rinse the J 35944-A with water. Do not store the J 35944-A with flushing solution in it.
3. After every third use, clean the J 35944-A as described in the instructions included with the tool.
4. Dispose of any waste water/solution and transmission fluid in accordance with local regulations.

Automatic Transmission Oil Cooler Flushing and Flow Test (J 45096)

GM studies indicate that plugged or restricted transmission oil coolers and pipes cause insufficient transmission lubrication and elevated operating temperatures which can lead to premature transmission failure. Many repeat repair cases could have been prevented by following published procedures for transmission oil cooler flushing and flow checking. This procedure includes flow checking and flushing the auxiliary transmission oil cooler, if equipped.

Important: Use the J 45096 or equivalent to flush and flow test the transmission oil cooler and the oil cooler pipes after the transaxle is removed for repairs. Only GM Goodwrench DEXRON®III automatic transmission fluid should be used when doing a repair on a GM transmission.

Time allowance for performing the cooler flow checking and flushing procedure has been included in the appropriate labor time guide operations since the 1987 model year. The service procedure steps for oil cooler flushing and flow testing are as follows

1. Machine Set-up
2. Determine Minimum Flow Rate
3. Back Flush
4. Forward Flush
5. Flow Test
6. Code Recording Procedure
7. Clean-up

Tools Required

1. J 35944-200 Cooler Flushing Adapter
2. J 45096 Transmission Oil Cooling System Flush and Flow Test Tool
3. Shop air supply with water/oil filters, regulator and pressure gage - minimum 90 psi
4. Eye protection
5. Rubber gloves

Scheme 768

Scheme 769

Scheme 770

1. Verify that the main power switch (1) is in the OFF position.
2. Place the main function switch (2) in the IDLE position.
3. Connect J 45096 to the vehicle 12V DC power source by connecting the red battery clip to the positive, +, battery post on the vehicle and connect the negative lead to a known good chassis ground.
4. Turn the main power switch to the ON position. CAUTION: Do not overfill the supply vessel. Damage to the unit may result. To verify the fluid level, view the LCD screen display while filling the unit to ensure that the fluid level does not exceed 32 quarts (30 liters).
5. Fill the supply tank with DEXRON®III/Mercon®, or equivalent, through the fill port.
6. Reinstall and tighten the fill cap.
7. Connect a shop air supply hose to the quick-disconnect on the rear panel marked SUPPLY AIR.

Scheme 771

Scheme 772

1. From the machine display, identify the temperature of the automatic transmission fluid that is stored in the supply vessel of J 45096 .
2. Determine whether the transmission oil cooler is steel or aluminum by using a magnet (1) at the cooler flange (2) at the radiator.
3. Refer to the table below. Using the temperature from step 1, locate on either the Steel MINIMUM Flow Rate table or the Aluminum MINIMUM Flow Rate table the minimum flow rate in gallons per minutes (GPM). Record the minimum flow rate in GPMs and the supply fluid temperature for further reference. Example: Fluid temperature: 75 °F Cooler type: Steel The MINIMUM flow rate for this example would be 0.8 GPM.
4. Inspect transmission oil cooler lines for damage or kinks that could cause restricted oil flow. Repair as needed and refer to the appropriate GM service manual procedures. Minimum Flow Rate In Gallons Per Minute (GPM) Temperature Range Steel Aluminum 65 to 66°F 0.6 gpm 0.5 gpm 67 to 70°F 0.7 gpm 0.6 gpm 71 to 75°F 0.8 gpm 0.7 gpm 76 to 80°F 0.9 gpm 0.8 gpm 81 to 84°F 1.0 gpm 0.9 gpm 85 to 89°F 1.1 gpm 1.0 gpm 90 to 94°F 1.2 gpm 1.1 gpm 95 to 98°F 1.3 gpm 1.2 gpm 99 to 103°F 1.4 gpm 1.3 gpm 104 to 108°F 1.5 gpm 1.4 gpm 109 to 112°F 1.6 gpm 1.5 gpm 113 to 117°F 1.7 gpm 1.6 gpm 118 to 120°F 1.8 gpm 1.7 gpm

Scheme 773

Scheme 774

Scheme 775

1. Connect the J 45096 adapters (1) to the vehicle's transmission oil cooler supply and return lines at the transmission. May require the use of J 35944-200 cooler flushing adapter.
2. Connect the black supply hose (1) to the return line, rear connector of the transmission, and the clear waste hose (2) to the feed line, front connector of the transmission, to the vehicle cooler lines. This is the reverse flow - backflush direction.
3. Turn the main function switch to the FLUSH position. Allow the machine to operate for 30 seconds.
4. Turn the main function switch to the IDLE position and allow the supply vessel pressure to dissipate.

Scheme 776

1. Disconnect the supply and waste hoses from the vehicle cooler lines. Reverse the supply and waste hoses to provide a normal flow direction.
2. Turn the main function switch to the FLUSH position and allow machine to operate for 30 seconds.

Important: If the flow rate is less than 0.5 gpm, the LCD displays an error message. Refer to the Troubleshooting section of the operation manual.

1. Turn the main function switch to the FLOW position and allow the oil to flow for 15 seconds. Observe and note the flow rate; this is the TESTED flow rate.
2. Compare the TESTED flow rate to the MINIMUM flow rate information previously recorded. If the TESTED flow rate is equal to or greater than the MINIMUM flow rate recorded, the oil cooling system is functioning properly. Perform Code Recording Procedure. If the TESTED flow rate is less than the MINIMUM flow rate previously recorded, repeat the back flush and forward flush procedures.
3. If the TESTED flow rate is less than the MINIMUM flow rate after the second test, perform Code Recording Procedure. Replace the transmission oil cooler. Reconnect supply and waste hoses to the cooler lines in the normal flow direction. Perform Flow Test. Perform Code Recording Procedure.

Code Recording Procedure

1. Turn the main function switch to the CODE position. Important: If power is interrupted prior to the recording of the seven-character code, the code will be lost and the flow rate test will need to be repeated. The flow test must run for a minimum of 8-10 seconds and be above 0.5 gpm for a code to be generated.
2. Record TESTED flow rate, temperature, cycle and seven-character flow code information on repair order.

Scheme 777

1. Turn the main function switch to the IDLE position and allow the supply vessel pressure to dissipate.
2. Turn the main power switch to the OFF position.
3. Disconnect the supply and waste hoses and the 12-volt power source from the vehicle. NOTE: A small amount of water may drain from the bottom of the unit when the air supply is disconnected. This is a normal operation of the built-in water separator.
4. Disconnect the air supply hose from J 45096 .
5. Dispose of the waste ATF in accordance with all applicable federal, state, and local requirements.

Scheme 778

Scheme 779

Scheme 780

Scheme 781

Forward Motion In Neutral

Forward Motion In Neutral

Inadequate Lubrication at Low Line or Heavy Loads

Inadequate Lubrication At Low Line Or Heavy Loads

Inadequate Lubrication

Inadequate Lubrication

Engine Stall In Neutral

Engine Stall In Neutral

Scheme 782

No Torque in Reverse and Third

No Torque In Reverse & Third

Transmission Overheats

Transmission Overheats

Transmission Overheats at WOT

Transmission Overheats At WOT

Scheme 783

Scheme 784

Shift Lever Indicates Wrong Gear

Shift Lever Indicates Wrong Gear

No Gear Selection

No Gear Selection

Scheme 785

Scheme 786

Remains In Park

Remains In Park

Difficult to Shift Out of Park

Difficult To Shift Out Of Park

Does Not Stay In Park

Does Not Stay In Park

Scheme 787

Scheme 788

No Second Gear - D1

No Second Gear - D1

Scheme 789

Scheme 790

Scheme 791

Scheme 792

Scheme 793

No Engine Braking - D2

No Engine Braking - D2

Scheme 794

Scheme 795

Scheme 796

Scheme 797

No Overrun Braking - D3

No Overrun Braking - D3

No Engine Braking - D3

No Engine Braking - D3

Scheme 798

First Gear Only - D4

First Gear Only - D4

Scheme 799

Scheme 800

Scheme 801

Scheme 802

Scheme 803

Scheme 804

Scheme 805

Scheme 806

Scheme 807

Soft Torque Converter Clutch (TCC) Apply

Soft Torque Converter Clutch (TCC) Apply

Torque Converter Clutch (TCC) Slipping

Torque Converter Clutch (TCC) Slipping

Scheme 808

Scheme 809

Converter Ballooning

Converter Ballooning

No Torque Multiplication

No Torque Multiplication

Scheme 810

Scheme 811

Engine Stall

Engine Stall

Scheme 812

Scheme 813

Scheme 814

Scheme 815

Third Gear Starts

Third Gear Starts

Scheme 816

Erratic Shift Quality

Erratic Shift Quality

Transmission Slips

Transmission Slips

Case Extension Bearing/Seal Failed

Case Extension Bearing/Seal Failed

Scheme 817

Scheme 818

Harsh Shift D to R

Harsh Shift D To R

Harsh Shift 3 to 4

Harsh Shift 3 To 4

Harsh Shift 4 to 3

Harsh Shift 4 To 3

Harsh Shift D4 to D3, D2, or D1

Harsh Shift D4 To D3, D2, Or D1

Scheme 819

Soft Shift Into R

Soft Shift Into R

Soft Shift R to D

Soft Shift R To D

Soft Shift 2 to 1

Soft Shift 2 To 1

Soft Shift 2 to 3

Soft Shift 2 To 3

Soft Shift 3 to 2

Soft Shift 3 To 2

Soft Shift D3 to D2

Soft Shift D3 To D2

Scheme 820

No D2 to D1

No D2 To D1

No D3 to D2

No D3 To D2

Scheme 821

Scheme 822

Scheme 823

1. Apply the parking brake.
2. Position the steering column shift lever to park.
3. Remove the knee bolster trim panel. Refer to «KNEE BOLSTER REPLACEMENT - LEFT»(/chevrolet/chevy-express-h2500/2003-2003/remont/gauges-instrument-panels/#instrument-panel-gages-and-console__knee-bolster-replacement-left) .
4. Remove the knee bolster bracket. Refer to «KNEE BOLSTER BRACKET REPLACEMENT - LEFT»(/chevrolet/chevy-express-h2500/2003-2003/remont/gauges-instrument-panels/#instrument-panel-gages-and-console__knee-bolster-bracket-replacement-left) .
5. Remove the clip securing the shift cable to the steering column bracket.
6. Remove the shift cable from the steering column shift control.
7. Remove the rubber grommet from the floor panel.
8. Remove the air cleaner assembly.
9. Remove the shift cable clips from the left front of the engine compartment.
10. Raise the vehicle.
11. Remove the shift cable clips from the left rear engine bracket.
12. Remove the shift cable from the stud ball.
13. Remove the locking clip from the cable at the bracket.
14. Lower the vehicle.
15. Remove the shift cable from the vehicle.

Installation Procedure

Important: Prior to installing the shift cable to the vehicle, ensure that the column shift lever and the transmission control lever are in the mechanical park position. The transmission control lever can be positioned to mechanical park by rotating the control lever clockwise until it reaches its full clockwise position.

Scheme 824

Scheme 825

Scheme 826

Scheme 827

1. Install the shift cable to the vehicle.
2. Raise the vehicle.
3. Remove the black shipping tab from the transmission end of the shift cable and discard the tab.
4. Install the ball stud on the transmission.
5. Install the shift cable to the transmission bracket.
6. Install the cable clip.
7. Install the shift cable end to the transmission shift control lever by pushing the cable end onto the transmission shift control lever stud ball.
8. Lock the primary lock.
9. Lock the secondary lock.
10. Install the shift cable clips to the engine brackets.
11. Lower the vehicle.
12. Install the rubber grommet to the floor panel. Important: Ensure the shift lever is in the Park position.
13. Install the shift cable to the steering column shift control.
14. Install the clip securing the shift cable to the steering column bracket.
15. Install the cable to the shift lever ball stud.
16. Adjust the shift cable. Refer to «Automatic Transmission Range Selector Cable Adjustment»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
17. Install the knee bolster bracket. Refer to «KNEE BOLSTER BRACKET REPLACEMENT - LEFT»(/chevrolet/chevy-express-h2500/2003-2003/remont/gauges-instrument-panels/#instrument-panel-gages-and-console__knee-bolster-bracket-replacement-left) .
18. Install the knee bolster trim panel. Refer to «KNEE BOLSTER REPLACEMENT - LEFT»(/chevrolet/chevy-express-h2500/2003-2003/remont/gauges-instrument-panels/#instrument-panel-gages-and-console__knee-bolster-replacement-left) .

Scheme 828

1. Position the transmission shift control lever into park.
2. Apply the park brake.
3. Raise and suitably support the vehicle.
4. Remove the end of the range selector cable from the range selector lever ball stud.
5. Position the transmission range selector lever to park. Rotate the range select lever clockwise until it reaches the full mechanical stop position.
6. Slide the locking tab retainer to the side.
7. Release the locking tab.
8. Install the end of the range selector cable to the range selector lever ball stud.
9. Engage the locking tab without disturbing the cable. This sets the adjustment.
10. Slide the locking tab retainer over the locking tab.
11. Lower the vehicle.
12. Check the transmission for proper operation.
13. Release the parking brake.

Park/Neutral Position Switch Replacement

Tools Required

J 41364-A Neutral Position Adjustment Tool

Removal Procedure

1. Apply the parking brake.
2. Shift the transmission into neutral.
3. Raise the vehicle.
4. Remove the nut securing the transmission control lever to the manual shaft.
5. Remove the transmission control lever from the manual shaft.
6. Disconnect the electrical connectors from the switch.
7. Remove the bolts securing the park/neutral position switch to the transmission.
8. Remove the park/neutral position switch from the manual shaft. If the park/neutral position switch did not slide off the manual shaft, file the outer edge of the manual shaft in order to remove any burrs.

Scheme 829

Scheme 830

Scheme 831

1. Install the switch to the transmission manual shaft by aligning the switch hub flats with the manual shaft flats.
2. Slide the switch onto the transmission manual shaft until the switch mounting bracket contacts the mounting bosses on the transmission. Important: If a new switch is being installed, the switch will come with a positive assurance bracket. The positive assurance bracket aligns the new switch in it proper position for installation and the use of neutral position adjustment tool will not be necessary.
3. Install the switch to the transmission with two bolts finger tight.
4. Position the tool J 41364-A onto the park/neutral position switch. Ensure that the two slots on the switch where the manual shaft is inserted are lined up with the lower two tabs on the tool. CAUTION: Refer to «FASTENER NOTICE»(/chevrolet/chevy-express-h2500/2003-2003/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) .
5. Rotate the tool until the upper locator pin on the tool is lined up with the slot on the top of the switch. Tighten Tighten the bolts securing the switch to 25 N.m (18 lb ft).
6. Remove the J 41364-A from the switch. If installing a new switch, remove the positive assurance bracket at this time.
7. Connect the electrical connectors to the switch.
8. Install the transmission control lever to the manual shaft with the nut. Tighten Tighten the control lever nut to 25 N.m (18 lb ft).
9. Lower the vehicle.
10. Check the switch for proper operation. The engine must start in the P (Park) or N (Neutral) positions only. If proper operation of the switch can not be obtained, replace the switch.

Park/Neutral Position Switch Adjustment

Important

1. The following procedure is for vehicles that have not had the switch removed or replaced. If the switch has been removed or replaced, refer to «Park/Neutral Position Switch Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__parkneutral-position-switch-replacement) for the proper adjustment procedure.
2. Apply the parking brake.
3. The engine must start in the P (Park) or N (Neutral) positions only.
4. Check the switch for proper operation. If adjustment is required, proceed as follows

1. Place the transmission range selector in the N (Neutral) position.
2. With an assistant in the drivers seat, raise the vehicle.
3. Loosen the park/neutral position switch mounting bolts.
4. With the vehicle in the N (Neutral) position, rotate the switch while the assistant attempts to start the engine.
5. Following a successful start, turn the engine off. CAUTION: Refer to «FASTENER NOTICE»(/chevrolet/chevy-express-h2500/2003-2003/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) .
6. Tighten the bolts securing the switch to the transmission. Tighten Tighten the bolts to 25 N.m (18 lb ft).
7. Lower the vehicle.
8. Check the switch for proper operation. The engine must start in the P (Park) or N (Neutral) positions only.
9. Replace the park/neutral position switch if proper operation can not be achieved. Refer to «Park/Neutral Position Switch Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__parkneutral-position-switch-replacement) .

Scheme 832

Scheme 833

1. Raise the vehicle.
2. Place a drain pan under the transmission oil pan.
3. Remove the oil pan drain plug, if equipped.
4. Remove the oil pan bolts.
5. Remove the oil pan.
6. Remove the gasket.
7. Remove the magnet.
8. Remove the oil filter.
9. Remove the filter neck seal.
10. The transmission oil pan gasket is reusable. Inspect the gasket and replace as needed.
11. Clean the transmission case and the oil pan gasket surfaces with solvent.

Scheme 834

Scheme 835

1. Install the filter neck seal.
2. Install the oil filter.
3. Install the oil pan gasket to the pan.
4. Install the magnet into the bottom of the pan. CAUTION: Refer to «FASTENER NOTICE»(/chevrolet/chevy-express-h2500/2003-2003/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) .
5. Install the oil pan to the transmission with seventeen bolts. Tighten Tighten the oil pan bolts to 11 N.m (97 lb in).
6. Apply a small amount of sealant GM P/N 12346004 to the treads of the drain plug, if equipped.
7. Install the oil pan drain plug, if equipped. Tighten Tighten the oil pan drain plug to 18 N.m (13 lb ft).
8. Lower the vehicle.
9. Fill the transmission to the proper level with Dexron® III transmission fluid. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__transmission-fluid-checking-procedure) .

Scheme 836

Scheme 837

1. Remove the engine air cleaner.
2. Remove the transmission fluid level indicator from the fluid fill tube.
3. Remove the bolt and the nut securing the transmission fluid fill tube to the engine.
4. Remove the engine cover. Refer to «ENGINE COVER REPLACEMENT»(/chevrolet/chevy-express-h2500/2003-2003/remont/exteriorinterior-trim/#interior-trim) .
5. Remove the nut securing the transmission fluid fill tube to the transmission stud.
6. Remove the upper fill tube from the vehicle.
7. Raise the vehicle.
8. Support the vehicle with safety stands.
9. Remove any dirt from the transmission where the fluid fill tube enters the transmission case.
10. Remove the drain plug from the transmission. Drain the fluid into an approved container.
11. Remove the transmission fluid fill tube from the transmission. Pull the tube upward from the transmission.
12. Remove the transmission fill tube seal.
13. Clean the metal parts using solvent. Do not allow the solvent to enter the transmission.
14. Air dry the parts.

Scheme 838

1. Install a new oil level indicator tube seal into the transmission case.
2. Install the bottom of oil level indicator tube into the seal.
3. Remove the safety stands.
4. Lower the vehicle.
5. Install the upper fill tube to the vehicle. CAUTION: Refer to «FASTENER NOTICE»(/chevrolet/chevy-express-h2500/2003-2003/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) .
6. Install the bolt and the nut securing the oil level indicator tube brackets to the engine. Tighten Tighten the bolt to 47 N.m (35 lb ft). Tighten the nut to 25 N.m (18 lb ft).
7. Install the nut securing the oil level indicator tube to the transmission stud. Tighten Tighten the nut to 25 N.m (18 lb ft).
8. Install the air cleaner.
9. Install the engine cover. Refer to «ENGINE COVER REPLACEMENT»(/chevrolet/chevy-express-h2500/2003-2003/remont/exteriorinterior-trim/#interior-trim) .
10. Fill the transmission fluid to the proper level. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__transmission-fluid-checking-procedure) .

Scheme 839

1. Raise the vehicle.
2. Disconnect the input speed sensor (1) electrical connector.
3. Remove the input speed sensor bolt.
4. Remove the input speed sensor (1) and the bracket assembly from the case.
5. Inspect the vehicle speed sensor assembly (1) for any evidence of damage.

Scheme 840

1. Lubricate the input speed sensor seal with automatic transmission fluid.
2. Install the input speed sensor (1) and the bracket assembly. CAUTION: Refer to «FASTENER NOTICE»(/chevrolet/chevy-express-h2500/2003-2003/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) .
3. Install the bolt. Tighten Tighten the bolt to 11 N.m (96 lb in).
4. Connect the input speed sensor electrical connector.
5. Lower the vehicle.

Scheme 841

1. Raise the vehicle. Important: This procedure is for 2WD vehicles. If the vehicle is equipped with 4WD, the output speed sensor is located on the transfer case.
2. Disconnect the output speed sensor (2) electrical connector.
3. Remove the output speed sensor bolt.
4. Remove the output speed sensor (2) and the bracket assembly from the case.
5. Inspect the output speed sensor assembly (2) for any evidence of damage.

Scheme 842

1. Lubricate the output speed sensor seal with automatic transmission fluid.
2. Install the output speed sensor (2) and the bracket assembly. CAUTION: Refer to «FASTENER NOTICE»(/chevrolet/chevy-express-h2500/2003-2003/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) .
3. Install the bolt. Tighten Tighten the bolt to 11 N.m (96 lb in).
4. Connect the output speed sensor electrical connector.
5. Lower the vehicle.

Scheme 843

Scheme 844

1. Raise the vehicle.
2. Remove the oil pan and filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
3. Remove the park/neutral position switch. Refer to «Park/Neutral Position Switch Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__parkneutral-position-switch-replacement) .
4. Remove the manual shaft nut and the pin.
5. Remove the detent lever and the actuator assembly. ]
6. Remove the bolts and the parking pawl bracket.
7. Remove the parking pawl return spring.
8. Use the modified screw extractor in order to remove the plug.
9. Remove the parking pawl shaft retainer, the shaft and the pawl. Important: If the manual shaft binds in the case during removal, file or sand the shaft in the area adjacent to the detent lever.
10. Remove the manual shaft.
11. Remove the manual shaft seal.

Scheme 845

Scheme 846

1. Install the pawl shaft.
2. Install the parking pawl.
3. Install the plug using a 8 mm or (5/16 inch) rod with Loctite® or the equivalent.
4. Install the retainer.
5. Install the pawl return spring.
6. Install the detent lever to the actuator assembly.
7. Install actuator assembly over the parking pawl.
8. Install the manual shaft seal.
9. Lubricate the manual shaft with transmission oil and install the manual shaft into the case.
10. Install the nut on the shaft.
11. Install the roll pin. CAUTION: Refer to «FASTENER NOTICE»(/chevrolet/chevy-express-h2500/2003-2003/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) .
12. Install the parking lock bracket with the two bolts. Tighten Tighten the bolts to 24 N.m (18 lb ft).
13. Install the park/neutral position switch. Refer to «Park/Neutral Position Switch Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__parkneutral-position-switch-replacement) .
14. Install the oil pan and filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
15. Lower the vehicle.
16. Fill the transmission to the proper level with Dexron® III transmission fluid. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__transmission-fluid-checking-procedure) .

Pressure Regulator Replacement

Tools Required

J 36850 Transjel®

Scheme 847

Scheme 848

1. Raise the vehicle.
2. Remove the transmission oil pan and the filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) . WARNING: Valve springs can be tightly compressed. Use care when removing retainers and plugs. Personal injury could result.
3. Remove the reverse boost valve bushing retainer ring (2).
4. Remove the following from the reverse boost valve cylinder: The reverse boost valve bushing The reverse boost valve The pressure regulator spring retainer The pressure regulator spring The pressure regulator valve The reverse boost valve bushing

Scheme 849

Scheme 850

1. Install the pressure regulator valve with J 36850 .
2. Pre-assemble the following parts: The reverse boost valve bushing A new reverse boost valve A new pressure regulator spring retainer The added isolator pressure regulator spring The pressure regulator spring
3. Install the pre-assembled parts into the pump bore.
4. Install the reverse boost valve bushing retainer ring while holding the reverse boost valve bushing in place. Ensure the retainer ring (2) is in the groove.
5. Install the transmission oil pan and the oil filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
6. Lower the vehicle.
7. Fill the transmission to the proper level with Dexron® III transmission fluid. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__transmission-fluid-checking-procedure) .

Scheme 851

Scheme 852

1. Raise the vehicle.
2. Remove the transmission oil pan and the oil filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) . WARNING: Valve springs can be tightly compressed. Use care when removing retainers and plugs. Personal injury could result.
3. Remove the valve bore plug retainer ring (1).
4. Remove the following parts: The valve bore plug The TCC valve The TCC valve spring

Scheme 853

Scheme 854

1. Install the following parts: The TCC valve spring The TCC valve The valve bore plug
2. Install the valve bore plug retainer ring (1).
3. Install the transmission oil pan and oil filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
4. Lower the vehicle.
5. Fill the transmission to the proper level with Dexron® III transmission fluid. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__transmission-fluid-checking-procedure) .

Accumulator Housing Replacement

Tools Required

J 25025 Guide Pins

1. Raise the vehicle.
2. Remove the control valve body assembly. Refer to «Valve Body and Pressure Switch Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__valve-body-and-pressure-switch-replacement) .
3. Remove the 3rd and 4th clutch accumulator housing bolts (1).
4. Remove the 3rd and 4th clutch accumulator housing (8).
5. Remove the accumulator housing gasket (6). The accumulator housing gasket may be stuck to the spacer plate (5).
6. Remove the 3rd clutch accumulator piston spring (7).
7. Remove the 4th clutch accumulator piston spring (2).
8. Remove the control valve body spacer plate (5).
9. Remove the control valve assembly to spacer plate gasket (4) from the spacer plate (5).

Third and Fourth Clutch Accumulator Disassembly

Important: Apply low pressure compressed air to the hole at the top of the accumulator housing to assist with the piston removal.

Scheme 855

Scheme 856

1. Remove the 3rd clutch accumulator piston (2).
2. Remove the 3rd clutch accumulator piston seals (1, 3).
3. Remove the 4th clutch accumulator piston pin retainer ring (5).
4. Remove the 4th clutch accumulator piston (4) and pin (2) from the accumulator housing (1).
5. Remove the 4th clutch accumulator piston pin (2) from the accumulator housing (1).
6. Remove the 4th clutch accumulator piston seal (3) from the accumulator housing (1).

Scheme 857

Scheme 858

1. Install the 3rd clutch accumulator piston inner (3) and outer (1) seals. Lubricate the 3rd clutch accumulator piston seals (1, 3) with Dexron® III automatic transmission fluid.
2. Install the 3rd clutch accumulator piston (2).
3. Install the 4th clutch accumulator piston seal (3). Lubricate the 4th clutch accumulator piston seal (3) with Dexron® III automatic transmission fluid.
4. Assemble the 4th clutch accumulator piston pin (2) with the 4th clutch accumulator piston (4).
5. Install the 4th clutch accumulator piston assembly into the accumulator housing (1).
6. Install the 4th clutch accumulator piston pin retainer ring (5) onto the 4th clutch accumulator piston pin (2).

Scheme 859

Scheme 860

Scheme 861

1. Install the J 25025 into the control valve body bolt hole where the manual shaft detent roller and spring assembly is mounted.
2. Install the control valve body gasket (2) onto the accumulator housing (1).
3. Install the control valve body spacer plate (3) onto the valve body gasket (2).
4. Install the third and fourth clutch accumulator housing gasket (3).
5. Install the third clutch accumulator piston spring (1). This spring is the longer of the two springs.
6. Install the fourth clutch accumulator piston spring (4).
7. Install the third and fourth clutch accumulator housing assembly (5) onto the control valve body assembly (2).
8. Install the six accumulator housing bolts (6). Start the bolts finger tight and work towards the opposite end. CAUTION: Refer to «FASTENER NOTICE»(/chevrolet/chevy-express-h2500/2003-2003/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) .
9. Tighten the accumulator housing bolts sequentially. Tighten Tighten the accumulator housing bolts to 11 N.m (97 lb in).
10. Remove the J 25025 .
11. Install the control valve body assembly. Refer to «Valve Body and Pressure Switch Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__valve-body-and-pressure-switch-replacement) .
12. Lower the vehicle.
13. Fill the transmission to the proper level with Dexron® III transmission fluid. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__transmission-fluid-checking-procedure) .

Scheme 862

1. Raise the vehicle.
2. Remove the transmission oil pan and filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
3. Remove the rear servo assembly from the transmission case as follows: Cover bolts (6) Cover (5) Cover gasket (4) Bottom retaining clip (3) Servo piston (2) Outer ring oil seal (1) Inner ring oil seal (7) Accumulator piston (8) Piston seal (9) Washer (10) Servo spring (11) Servo spring retainer (12) Selective pin (13) Accumulator spring (14)

Scheme 863

1. Install the rear servo assembly to the transmission case as follows: Accumulator spring (14) Selective pin (13) Servo spring retainer (12) Servo spring (11) Washer (10) Piston seal (9) Accumulator piston (8) Inner ring oil seal (7) Outer ring oil seal (1) Servo piston (2) Bottom retaining clip (3) Cover gasket (4) Cover (5) Cover Bolt (6) CAUTION: Refer to «FASTENER NOTICE»(/chevrolet/chevy-express-h2500/2003-2003/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) .
2. Install the cover bolts (6). Tighten Tighten the bolts to 24 N.m (18 lb ft).
3. Install the transmission oil pan and filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
4. Lower the vehicle.
5. Fill the transmission to the proper level with Dexron® III transmission fluid. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__transmission-fluid-checking-procedure) .

Important: Perform the following procedure when removing the retaining rings and cooler lines from the quick connect fittings located on the radiator and/or the transmission.

Scheme 864

Scheme 865

1. Pull the plastic cap back from the quick connect fitting and down along the cooler line about 5 cm (2 in).
2. Using a bent-tip screwdriver, pull on one of the open ends of the retaining ring in order to rotate the retaining ring around the quick connect fitting until the retaining ring is out of position and can be completely removed.
3. Remove the retaining ring from the quick connect fitting.
4. Discard the retaining ring.
5. Pull the cooler line straight out from the quick connect fitting.

Important

1. Do not reuse any of the existing oil lines or oil line fittings if there is excessive corrosion.
2. Do not reuse any of the existing retaining rings that were removed from the existing quick connect fittings. Install new retaining rings.
3. Ensure the following procedures are performed when installing the new retaining rings onto the fittings.

Scheme 866

Scheme 867

Scheme 868

Scheme 869

Scheme 870

Scheme 871

Scheme 872

Scheme 873

Scheme 874

Scheme 875

1. Install a new retaining ring into the quick connect fitting using the following procedure
2. Hook one of the open ends of the retaining ring in one of the slots in the quick connect fitting.
3. Rotate the retaining ring around the fitting until the retaining ring is positioned with all three ears through the three slots on the fitting.
4. Do not install the new retaining ring onto the fitting by pushing the retaining ring.
5. Ensure that the three retaining ring ears are seen from inside the fitting and that the retaining ring moves freely in the fitting slots.
6. Install the cooler line into the quick connect fitting.
7. Insert the cooler line end into the quick connect fitting until a click is either heard or felt.
8. Do not use the plastic cap on the cooler line in order to install the cooler line into the fitting.
9. Pull back sharply on the cooler line in order to ensure that the cooler line is fastened into the quick connect fitting. Important: Do not manually depress the retaining clip when installing the plastic cap.
10. Position (snap) the plastic cap onto the fitting. Do not manually depress the retaining ring when installing the plastic cap onto the quick connect fitting.
11. Ensure that the plastic cap is fully seated against the fitting.
12. Ensure that no gap is present between the cap and the fitting.
13. Ensure that the yellow identification band on the tube is hidden within the quick connect fitting.
14. A hidden yellow identification band indicates proper joint seating.
15. Fill the transmission to the proper level with Dexron® III transmission fluid. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__transmission-fluid-checking-procedure) .

Scheme 876

1. Raise the vehicle.
2. Remove the oil pan and filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
3. Remove the six forward servo cover bolts, cover, and gasket.
4. Remove the following parts: Forward servo piston pin (5) O-ring seal (4) Servo piston (3) Retainer (2) Piston spring (1)

Scheme 877

1. Install the following parts: Piston spring (1) Retainer (2) Servo piston (3) O-ring seal (4) Forward servo piston pin (5) CAUTION: Refer to «FASTENER NOTICE»(/chevrolet/chevy-express-h2500/2003-2003/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) .
2. Install the forward servo gasket, cover, and bolts. Tighten Tighten the bolts to 24 N.m (18 lb ft).
3. Install the oil pan and filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
4. Lower the vehicle.
5. Fill the transmission to the proper level with Dexron® III transmission fluid. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__transmission-fluid-checking-procedure) .

Scheme 878

Scheme 879

Scheme 880

Scheme 881

Scheme 882

Scheme 883

Scheme 884

1. Raise the vehicle.
2. Support the vehicle with safety stands.
3. Remove the 2 oil cooler lines from the radiator.
4. If equipped with the auxiliary transmission oil cooler, remove the outlet pipe from the auxiliary cooler pipe.
5. Remove the 2 oil cooler lines from the transmission.
6. Remove the 2 oil cooler lines from the clips on the frame rail. Important: Perform the following procedures when removing the retaining ring and cooler line from the quick connect fitting on the transmission.
7. Pull the plastic cap back from the quick connect fitting and down along the cooler line about two inches.
8. Using a bent-tip screwdriver, pull on one of the open ends of the retaining ring in order to rotate the retaining ring around the quick connect fitting until the retaining ring is out of position and can be completely removed.
9. Remove the retaining ring from the quick connect fitting.
10. Discard the retaining ring.
11. Pull the cooler line straight out from the quick connect fitting.
12. Remove the retaining ring (E-clips) securing the cooler line to the quick connect in order to remove the remaining cooler lines from the remaining quick connect fittings.
13. Remove the cooler lines from the vehicle.
14. Lower the vehicle.

Scheme 885

Scheme 886

Scheme 887

Scheme 888

Scheme 889

Scheme 890

Scheme 891

Scheme 892

Scheme 893

Scheme 894

Scheme 895

Scheme 896

Scheme 897

Scheme 898

Scheme 899

1. Raise the vehicle.
2. Install the transmission oil cooler line to the vehicle. Important: Do not reuse any of the existing retaining rings that were removed from the existing quick connect fittings. All retaining rings being installed must be New.
3. Install the new retaining ring (E-clip) into the quick connect fitting.
4. Install the 2 cooler lines to the radiator.
5. If equipped with the auxiliary oil cooler, install the inlet line to the radiator and the outlet to the auxiliary cooler line.
6. Install the 2 oil cooler lines to the transmission.
7. Hook one of the open ends of the retaining ring in one of the slots in the quick connect fitting.
8. Rotate the retaining ring around the fitting until the retaining ring is positioned with all three ears through the three slots on the fitting.
9. Do not install the new retaining ring onto the fitting by pushing the retaining ring down over the fitting.
10. Ensure that the three retaining ring ears are seen from inside the fitting and that the retaining ring moves freely in the fitting slots.
11. Install the new retaining ring (E-clip) into the remaining quick connect fittings. NOTE: Ensure that the cooler line being installed has a plastic cap on each end that connects to a quick connect fitting. If no plastic cap exists, or the plastic cap is damaged, obtain a new plastic cap and position on to the cooler line prior to the cooler line installation.
12. Install the cooler line into the quick connect fitting.
13. Insert the cooler line end into the quick connect fitting until a click is either heard or felt.
14. Do not use the plastic cap on the cooler line in order to install the cooler line into the fitting.
15. Pull back sharply on the cooler line in order to ensure that the cooler line is fastened into the quick connect fitting.
16. Position (snap) the plastic cap onto the fitting. Do not manually depress the retaining ring when installing the plastic cap onto the quick connect fitting.
17. Ensure that the plastic cap is fully seated against the fitting.
18. Ensure that no gap is present between the cap and the fitting.
19. Ensure that the yellow identification band on the tube is hidden within the quick connect fitting. A hidden yellow identification band indicates proper joint seating.
20. Do not install the cooler line into the fitting incorrectly.
21. If you cannot position the plastic cap against the fitting, remove the retaining ring from the quick connect fitting per step 3 of the cooler line removal procedure. Check the retaining ring and the tube end in order to ensure neither is bent. Replace the cooler line or the retaining ring if necessary, and reinstall per Step 1 of the cooler line installation procedure.
22. Install the cooler line into the quick connect fitting again in order to install the remaining cooler lines into the remaining quick connect fittings.
23. Install the engine or transmission cooler lines to the frame.
24. Lower the vehicle.

Scheme 900

Scheme 901

1. Remove the grille assembly. Refer to «GRILLE REPLACEMENT (UPLEVEL)»(/chevrolet/chevy-express-h2500/2003-2003/remont/exteriorinterior-trim/#exterior-trim) or «GRILLE REPLACEMENT (BASE)»(/chevrolet/chevy-express-h2500/2003-2003/remont/exteriorinterior-trim/#exterior-trim) .
2. Disconnect the 2 lines from the auxiliary cooler.
3. Remove the lines from the push clips on the auxiliary cooler mounting bracket.
4. Raise the vehicle.
5. Remove the lower bolts from the auxiliary cooler mounting bracket.
6. Lower the vehicle.
7. Remove the upper bolts.
8. Remove the auxiliary oil cooler from the vehicle.

Scheme 902

Scheme 903

1. Install the oil cooler into the vehicle. CAUTION: Refer to «FASTENER NOTICE»(/chevrolet/chevy-express-h2500/2003-2003/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) .
2. Install the upper bolts into the oil cooler bracket. Tighten Tighten the bolts to 10 N.m (89 lb in).
3. Raise the vehicle.
4. Install the lower bolts to the oil cooler bracket. Tighten Tighten the bolts to 10 N.m (89 lb in).
5. Lower the vehicle.
6. Connect the oil cooler lines to the auxiliary oil cooler.
7. Attach the oil cooler lines to the push clips in the mounting bracket.
8. Reinstall the grille assembly. Refer to «GRILLE REPLACEMENT (UPLEVEL)»(/chevrolet/chevy-express-h2500/2003-2003/remont/exteriorinterior-trim/#exterior-trim) or «GRILLE REPLACEMENT (BASE)»(/chevrolet/chevy-express-h2500/2003-2003/remont/exteriorinterior-trim/#exterior-trim) .

Scheme 904

1. Raise the vehicle.
2. Remove the two bolts securing the transmission heat shield to the cross member.
3. Remove the transmission heat shield from the cross member.

Scheme 905

1. Install the transmission heat shield to the cross member. CAUTION: Refer to «FASTENER NOTICE»(/chevrolet/chevy-express-h2500/2003-2003/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) .
2. Install the two bolts securing the transmission heat shield to the cross member. Tighten Tighten the bolts to 17 N.m (13 lb ft).
3. Lower the vehicle.

Scheme 906

1. Remove the vent hose clip.
2. Remove the vent hose from the transmission vent.

Scheme 907

1. Install the vent hose to the transmission.
2. Install the vent hose to the clip. CAUTION: Refer to «FASTENER NOTICE»(/chevrolet/chevy-express-h2500/2003-2003/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) .
3. Install the bolt and the clamp. Tighten Tighten the bolt to 10 N.m (89 lb in).

Manual Shift Shaft Seal Replacement

Tools Required

1. J 43911 Selector Shaft Seal Remover
2. J 43909 Selector Shaft Seal Installer

1. Remove the Park/Neutral Position (PNP) Switch. Refer to «Park/Neutral Position Switch Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__parkneutral-position-switch-replacement) .
2. Be sure that the jackscrew for J 43911 is backed off and will not interfere with installation of the removal tool. Slide the seal remover tool over the selector shaft (2) with the threaded end of the tool towards the seal.
3. Rotate the removal tool so that the threads on the end of the tool engage the steel shell (1) of the seal. Use a wrench to be sure that the removal tool is firmly attached to the seal shell.
4. Rotate the jackscrew in the clockwise direction to remove the seal from the bore. Discard the seal that was removed.

Scheme 908

1. Carefully slide a new selector shaft seal (1) over the selector shaft (2) with the wide face of the steel case facing outward. Position the seal so that it is starting to enter the seal bore.
2. Obtain J 43909 and remove the inner sleeve so that the tool will slide over the selector shaft.
3. Slide the J 43909 into position so that the end of the tool contacts the seal being installed. Use a mallet to strike the J 43909 and drive the new seal into the seal bore until it is seated at the bottom of the bore.
4. Install the PNP Switch. Refer to «Park/Neutral Position Switch Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__parkneutral-position-switch-replacement) .

Valve Body and Pressure Switch Replacement

Tools Required

1. J 25025 Guide Pins
2. J 36850 Transjel®

Scheme 909

Scheme 910

Scheme 911

Scheme 912

Scheme 913

Scheme 914

Scheme 915

Scheme 916

1. Ensure that removal of the valve body is necessary before proceeding. Important: The following components can be serviced without removing the valve body from the transmission: The 2-3 solenoid (1) The internal wiring harness (2) The 1-2 shift solenoid (3) The transmission fluid temperature sensor (4) The transmission fluid pressure manual valve position switch (5) The pressure control solenoid (6) The torque converter clutch pulse width modulation (TCC PWM) solenoid (7)
2. Remove the fluid level indicator.
3. Raise the vehicle.
4. Remove the oil pan, gasket, and filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
5. Disconnect the internal wire harness from the transmission fluid pressure (TFP) manual valve position switch. Important: Use care not to loose the 5 O-rings that are located between the TFP manual valve position switch and the valve body.
6. Remove the control valve body bolts (1) that retain the (TFP) manual valve position switch (2) to the control valve body.
7. Remove the TFP manual valve position switch.
8. Disconnect the internal wiring harness electrical connectors from the remaining valve body electrical components.
9. Remove the lube oil pipe bolt (6) and retainer (7).
10. Remove the lube oil pipe (5).
11. Remove the bolts and remove the manual shaft detent spring (3). Important: Keep the control valve body level when lowering it from the vehicle. This will prevent the loss of checkballs located in the transmission case passages.
12. Remove the remaining control valve body bolts.
13. Carefully lower the valve body down from the transmission case. Use care not to drop the manual shaft valve.
14. Remove the control valve assembly (2) which includes the following: The accumulator housing assembly (1) The control valve assembly to the spacer plate gasket The spacer plate
15. Remove the manual valve (1) from the control valve body.
16. Inspect the manual valve for nicks and burrs.
17. Remove the spacer plate to case gasket (2) from the case. The gasket may stick to the spacer plate.
18. Remove the PWM screen (1) from the case passage.
19. Remove the manual 2-1 band servo assembly (1).
20. Remove the servo piston cushion spring (2).
21. Remove the manual 2-1 band servo piston pin retainer ring (4).
22. Remove the manual 2-1 band servo piston pin (1).
23. Remove the manual 2-1 band servo piston seal (2). Important: Do not use a magnet in order to remove the checkballs. Using a magnet to remove the checkballs may magnetize the checkballs, causing metal particles to stick.
24. Remove the eight checkballs (nine checkballs for some models).

Scheme 917

Scheme 918

Scheme 919

Scheme 920

Scheme 921

Scheme 922

Scheme 923

Scheme 924

Scheme 925

1. Install the 8 checkballs (9 checkballs for some models) into the control valve body. The checkball marked as number 2, is used on RCP, RDP, ZJP and ZLP models only To hold the checkballs in place, use the J 36850 .
2. Install the PWM screen into the control valve body.
3. Install a new manual 2-1 band servo piston seal (2) onto the manual 2-1 band servo piston (3).
4. Install the manual 2-1 band servo piston pin (1) into the manual 2-1 band servo piston (3).
5. Install the manual 2-1 band servo piston pin retainer ring (4).
6. Install the manual 2-1 band servo piston cushion spring (2). Important: Make certain that the tapered end of the manual 2-1 band servo piston pin contacts the manual 2-1 band.
7. Install the manual 2-1 band servo piston assembly (1).
8. Install the manual valve (1) into the control valve body.
9. To aid in alignment and assembly, install tool J 25025 .
10. Install the control valve body gasket (6).
11. Install the control valve body assembly (5). Attach the manual valve to the detent lever while installing the control valve body assembly.
12. Install the transmission fluid pressure manual valve position switch (2).
13. Install the transmission fluid pressure manual valve position switch bolts (1) finger tight.
14. Tighten the bolts in the order shown to 11 N.m (97 lb in).
15. Remove the J 25025 .
16. Install the manual shaft detent roller and spring assembly (3) and bolts.
17. Install the two wiring harness clips (1) and bolts (2).
18. Install the wiring harness clip (1) and bolts (2).
19. Install the lube oil pipe (5) with the short end into the control valve body.
20. Install the lube oil pipe retainer (7) and the bolt (6). CAUTION: Refer to «FASTENER NOTICE»(/chevrolet/chevy-express-h2500/2003-2003/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) .
21. Install the control valve body bolts. Tighten Tighten the bolts in the order shown to 11 N.m (97 lb in).
22. Install the remaining control valve body bolts. Tighten Tighten the remaining bolts to 11 N.m (97 lb in).
23. Connect the internal wiring harness to the valve body electrical components.
24. Install the oil pan, gasket, and filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
25. Lower the vehicle.
26. Fill the transmission to the proper level using approved fluid.
27. Fill the transmission to the proper level with Dexron® III transmission fluid. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__transmission-fluid-checking-procedure) .

Transmission Extension Housing Rear Oil Seal Replacement

Tools Required

1. J 41505 Rear Lubricant Seal Installer
2. J 6125-1B Slide Hammer Adapter
3. J 23129 Universal Seal Remover
4. J 36850 Transjel®

Scheme 926

1. Raise the vehicle.
2. Place a drain pan under the vehicle.
3. Remove the propeller shaft. Refer to «PROPELLER SHAFT REPLACEMENT - ONE PIECE»(/chevrolet/chevy-express-h2500/2003-2003/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints) or «PROPELLER SHAFT REPLACEMENT - TWO PIECE»(/chevrolet/chevy-express-h2500/2003-2003/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints) .
4. Using the J 6125-1B (1) and the J 23129 (2), remove the output shaft seal (3) from the extension housing (4).
5. Inspect the case extension housing for damage. Replace the extension housing if necessary. Refer to «Transmission Extension Housing Assembly Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .

Scheme 927

1. Lubricate the inside diameter of the new seal with J 36850.
2. Use the J 41505 (1) with a soft faced mallet to install the seal (2).
3. Install the seal (2) to the extension housing (3).
4. Install the propeller shaft. Refer to «PROPELLER SHAFT REPLACEMENT - ONE PIECE»(/chevrolet/chevy-express-h2500/2003-2003/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints) or «PROPELLER SHAFT REPLACEMENT - TWO PIECE»(/chevrolet/chevy-express-h2500/2003-2003/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints) .
5. Remove the drain pan and lower the vehicle.
6. Fill the transmission to the proper level with approved fluid.

1. Raise and suitably support the vehicle.
2. Support the transmission with a transmission jack.
3. Place a drain pan under the vehicle.
4. Remove the propeller shaft. Refer to «PROPELLER SHAFT REPLACEMENT - ONE PIECE»(/chevrolet/chevy-express-h2500/2003-2003/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints) or «PROPELLER SHAFT REPLACEMENT - TWO PIECE»(/chevrolet/chevy-express-h2500/2003-2003/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints) .
5. Remove the transmission support and the transmission mount. Refer to «Transmission Mount Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
6. Remove the case extension bolts (3).
7. Remove the case extension (1).
8. Remove and discard the case extension O ring seal (2).

Scheme 928

1. Install a new case extension O ring seal (2).
2. Install the case extension (1). CAUTION: Refer to «FASTENER NOTICE»(/chevrolet/chevy-express-h2500/2003-2003/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) .
3. Install the case extension bolts (3). Tighten Tighten the case extension bolts (3) to 34 N.m (25 lb ft).
4. Install the transmission support and the transmission mount. Refer to «Transmission Mount Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
5. Install the propeller shaft. Refer to «PROPELLER SHAFT REPLACEMENT - ONE PIECE»(/chevrolet/chevy-express-h2500/2003-2003/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints) or «PROPELLER SHAFT REPLACEMENT - TWO PIECE»(/chevrolet/chevy-express-h2500/2003-2003/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints) .
6. Remove the drain pan and the transmission jack.
7. Lower the vehicle
8. Fill the transmission to the proper level with Dexron® III transmission fluid. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__transmission-fluid-checking-procedure) .

Scheme 929

Scheme 930

1. Raise and support the vehicle.
2. Support the transmission with a transmission jack.
3. Remove the transmission support. Refer to «TRANSMISSION SUPPORT REPLACEMENT»(/chevrolet/chevy-express-h2500/2003-2003/remont/exterior-body-panels/#frame-and-underbody) .
4. Remove the transmission mount mounting bolts, for RWD vehicles.
5. Remove the transmission mount mounting bolts, for 4WD vehicles.
6. Remove the transmission mount from the vehicle.

Scheme 931

Scheme 932

1. Install the transmission mount to the vehicle. CAUTION: Refer to «FASTENER NOTICE»(/chevrolet/chevy-express-h2500/2003-2003/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) .
2. Install the transmission mount mounting bolts, for 4WD vehicles. Tighten Tighten the bolts to 50 N.m (37 lb ft).
3. Install the transmission mount mounting bolts, for RWD vehicles. Tighten Tighten the bolts to 50 N.m (37 lb ft).
4. Install the transmission support. Refer to «TRANSMISSION SUPPORT REPLACEMENT»(/chevrolet/chevy-express-h2500/2003-2003/remont/exterior-body-panels/#frame-and-underbody) .
5. Remove the transmission jack.
6. Lower the vehicle.

Scheme 933

Scheme 934

Scheme 935

Scheme 936

Scheme 937

1. Disconnect the battery negative cable assembly from the battery negative terminal.
2. Raise the vehicle.
3. Support the vehicle with safety stands.
4. If equipped with All Wheel Drive (AWD), remove the transfer case. Refer to «TRANSFER CASE»(/chevrolet/chevy-express-h2500/2003-2003/remont/transfer-case/#transfer-case-removal-installation) .
5. Disconnect the range selector cable from the transmission bracket and from the range selector lever.
6. Remove the rear propeller shaft. Refer to «PROPELLER SHAFT REPLACEMENT - ONE PIECE»(/chevrolet/chevy-express-h2500/2003-2003/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints) or «PROPELLER SHAFT REPLACEMENT - TWO PIECE»(/chevrolet/chevy-express-h2500/2003-2003/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints) .
7. Support the transmission with a transmission jack.
8. Remove the transmission support. Refer to «TRANSMISSION SUPPORT REPLACEMENT»(/chevrolet/chevy-express-h2500/2003-2003/remont/exterior-body-panels/#frame-and-underbody) .
9. Remove the exhaust pipe from the exhaust manifolds and the muffler assembly from the exhaust pipe. Refer to «CATALYTIC CONVERTER REPLACEMENT (4.3L)»(/chevrolet/chevy-express-h2500/2003-2003/remont/exhaust/#engine-exhaust-system) or «CATALYTIC CONVERTER REPLACEMENT (DUAL EXHAUST - RIGHT)»(/chevrolet/chevy-express-h2500/2003-2003/remont/exhaust/#engine-exhaust-system) or «CATALYTIC CONVERTER REPLACEMENT (DUAL EXHAUST - LEFT)»(/chevrolet/chevy-express-h2500/2003-2003/remont/exhaust/#engine-exhaust-system) .
10. Remove the starter motor. Refer to «STARTER MOTOR REPLACEMENT (4.8L, 5.3L & 6.0L)»(/chevrolet/chevy-express-h2500/2003-2003/remont/starter/#starting-system__starter-motor-replacement-48l-53l) or «STARTER MOTOR REPLACEMENT (4.3L)»(/chevrolet/chevy-express-h2500/2003-2003/remont/starter/#starting-system__starter-motor-replacement-43l) .
11. Mark the flywheel and the torque converter alignment.
12. Remove the bolts that attach the torque converter to the engine flywheel.
13. Remove the transmission vent hose and the wiring harness from the transmission.
14. Remove the transmission fluid fill tube and the fill tube seal from the transmission. Refer to «Filler Tube and Seal Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
15. Plug the fluid fill tube opening in the transmission.
16. Disconnect the transmission oil cooler pipes from the transmission. Refer to «Transmission Fluid Cooler Hose/Pipe Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
17. Plug the transmission oil cooler pipe connectors in the transmission case.
18. Disconnect the wiring harness connectors from the transmission vehicle speed sensor and the park/neutral position switch.
19. Remove all vehicle harness wires, harness clips, tubes, brackets, and lines that may interfere with the removal of the transmission from the vehicle.
20. Remove the studs and the bolts securing the transmission to the engine.
21. Pull the transmission straight back.
22. Remove the transmission from the vehicle.
23. Inspect all the components for wear and damage.
24. Inspect all the seals and the fittings for signs of wear.
25. Inspect the torque converter for stripped or broken weld nuts.
26. Inspect the transmission case for cracks.

Scheme 938

Scheme 939

Scheme 940

Scheme 941

1. Support the transmission with a transmission jack.
2. Raise the transmission into place.
3. Slide the transmission straight onto the locating pins while lining up the marks on the flywheel and the torque converter. Important: The torque converter must rotate freely by hand. Do not install the transmission fluid fill tube. CAUTION: Refer to «FASTENER NOTICE»(/chevrolet/chevy-express-h2500/2003-2003/remont/oem-general-information/#gm-vehicles-cautions-notices__fastener-notice) .
4. Install the bolts that secure the transmission to the engine. Tighten Tighten the studs and the bolts to 47 N.m (34 lb ft).
5. Install the bolts securing the torque converter to the engine flywheel. Tighten First tighten all the bolts finger tight in order to insure proper converter seating. Tighten the bolts to 63 N.m (46 lb ft).
6. If equipped with All Wheel Drive (AWD), install the transfer case. Refer to «TRANSFER CASE»(/chevrolet/chevy-express-h2500/2003-2003/remont/transfer-case/#transfer-case-removal-installation) .
7. Install the wiring harness connectors to the vehicle speed sensor and the park neutral position switch.
8. Position and install all vehicle harness wires, harness clips, tubes, brackets, and lines that were removed or moved prior to the transmission removal.
9. Remove the two plugs from the transmission case cooling line connectors.
10. Install the transmission oil cooler pipes. Refer to «Transmission Fluid Cooler Hose/Pipe Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
11. Install the transmission fluid fill tube and the fill tube seal. Refer to «Filler Tube and Seal Replacement»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement) .
12. Install the transmission vent hose and the wiring harness to the transmission.
13. Install the starter motor. Refer to «STARTER MOTOR REPLACEMENT (4.8L, 5.3L & 6.0L)»(/chevrolet/chevy-express-h2500/2003-2003/remont/starter/#starting-system__starter-motor-replacement-48l-53l) or «STARTER MOTOR REPLACEMENT (4.3L)»(/chevrolet/chevy-express-h2500/2003-2003/remont/starter/#starting-system__starter-motor-replacement-43l) .
14. Install the exhaust pipe to the exhaust manifolds and the muffler assembly to the exhaust pipe. Refer to «CATALYTIC CONVERTER REPLACEMENT (4.3L)»(/chevrolet/chevy-express-h2500/2003-2003/remont/exhaust/#engine-exhaust-system) or «CATALYTIC CONVERTER REPLACEMENT (DUAL EXHAUST - RIGHT)»(/chevrolet/chevy-express-h2500/2003-2003/remont/exhaust/#engine-exhaust-system) or «CATALYTIC CONVERTER REPLACEMENT (DUAL EXHAUST - LEFT)»(/chevrolet/chevy-express-h2500/2003-2003/remont/exhaust/#engine-exhaust-system) . Install the transmission support. Refer to «TRANSMISSION SUPPORT REPLACEMENT»(/chevrolet/chevy-express-h2500/2003-2003/remont/exterior-body-panels/#frame-and-underbody) .
15. Remove the transmission jack and the engine support stands.
16. Install the rear propeller shaft.
17. Install the transmission range select cable to the transmission range select lever and the bracket.
18. Flush the transmission oil cooler and the pipes whenever you remove the transmission for overhaul, or replacement of the torque converter, the pump, or the transmission case. Refer to «Automatic Transmission Oil Cooler Flushing and Flow Test (J 35944-A)»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__automatic-transmission-oil-cooler-flushing-and) or «Automatic Transmission Oil Cooler Flushing and Flow Test (J 45096)»(/chevrolet/chevy-express-h2500/2003-2003/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-service-replacement__automatic-transmission-oil-cooler-flushing-and) .
19. Remove the safety stands.
20. Lower the vehicle.
21. Fill the transmission to the proper level with approved fluid.
22. Connect the battery negative cable assembly to the battery negative terminal. Tighten Tighten the terminal bolt to 15 N.m (11 lb ft).

How to Use This Section

This section provides the following information

1. General diagnosis information on transmissions
2. Procedures for diagnosing the Hydra-Matic® transmission

When you diagnose any condition of the Hydra-Matic® transmission, begin with Diagnostic Starting Point. This procedure indicates the proper path of diagnosing the transmission by describing the basic checks. This procedure will then refer you to the locations of specific checks. After you have determined the cause of a condition, refer to Repair Instructions for repair procedures, if the faulty component is not serviceable without removing the transmission from the vehicle, refer to Unit Repair for repair information.

Basic Knowledge

You must be familiar with some basic electronics in order to use this section of the service manual. You should also be able to use the following special tools

1. A Digital Multimeter (DMM)
2. A circuit tester
3. Jumper wires or leads
4. A line pressure gauge set

Diagnosis

Scheme 942

Throttle Positions

Engine Braking: A condition where the engine is used to slow the vehicle by manually downshifting during a zero throttle coastdown.

Full Throttle Detent Downshift: A quick apply of the accelerator pedal to its full travel, forcing a downshift.

Heavy Throttle: Approximately 3/4 of accelerator pedal travel, 75 percent throttle position.

Light Throttle: Approximately 1/4 of accelerator pedal travel, 25 percent throttle position.

Medium Throttle: Approximately 1/2 of accelerator pedal travel, 50 percent throttle position.

Minimum Throttle: The least amount of throttle opening required for an upshift.

Wide Open Throttle (WOT): Full travel of the accelerator pedal, 100 percent throttle position.

Zero Throttle Coastdown: A full release of the accelerator pedal while the vehicle is in motion and in drive range.

Shift Condition Definitions

Bump: A sudden and forceful apply of a clutch or a band.

Chuggle: A bucking or jerking. This condition may be most noticeable when the converter clutch is engaged. It is similar to the feel of towing a trailer.

Delayed: A condition where a shift is expected but does not occur for a period of time. This could be described as a clutch or band engagement that does not occur as quickly as expected during a part throttle or wide open throttle apply of the accelerator, or during manual downshifting to a lower range. This term is also defined as LATE or EXTENDED.

Double Bump - Double Feel: Two sudden and forceful applies of a clutch or a band.

Early: A condition where the shift occurs before the car has reached proper speed. This condition tends to labor the engine after the upshift.

End Bump: A firmer feel at the end of a shift than at the start of the shift. This is also defined as END FEEL or SLIP BUMP.

Firm: A noticeably quick apply of a clutch or band that is considered normal with a medium to heavy throttle. This apply should not be confused with HARSH or ROUGH.

Flare: A quick increase in engine RPM along with a momentary loss of torque. This most generally occurs during a shift. This condition is also defined as SLIPPING.

Harsh - Rough: A more noticeable apply of a clutch, or band than FIRM. This condition is considered undesirable at any throttle position.

Hunting: A repeating quick series of upshifts and downshifts that causes a noticeable change in engine RPM, such as a 4-3-4 shift pattern. This condition is also defined as BUSYNESS.

Initial Feel: A distinctly firmer feel at the start of a shift than at the finish of the shift.

Late: A shift that occurs when the engine RPM is higher than normal for a given amount of throttle.

Shudder: A repeating jerking condition similar to CHUGGLE but more severe and rapid. This condition may be most noticeable during certain ranges of vehicle speed.

Slipping: A noticeable increase in engine RPM without a vehicle speed increase. A slip usually occurs during or after initial clutch or band apply.

Soft: A slow, almost unnoticeable clutch or band apply with very little shift feel.

Surge: A repeating engine related condition of acceleration and deceleration that is less intense than CHUGGLE.

Tie-Up: A condition where two opposing clutch and/or bands are attempting to apply at the same time causing the engine to labor with a noticeable loss of engine RPM.

Noise Conditions

Drive Link Noise: A whine or growl that increases or fades with vehicle speed, and is most noticeable under a light throttle acceleration. It may also be noticeable in PARK or NEUTRAL operating ranges with the vehicle stationary.

Final Drive Noise: A hum related to vehicle speed which is most noticeable under a light throttle acceleration.

Planetary Gear Noise: A whine related to vehicle speed, which is most noticeable in FIRST gear, SECOND gear, FOURTH gear or REVERSE. The condition may become less noticeable, or go away, after an upshift.

Pump Noise: A high pitched whine that increases in intensity with engine RPM. This condition may also be noticeable in all operating ranges with the vehicle stationary or moving.

Torque Converter Noise: A whine usually noticed when a vehicle is stopped, and the transmission is in DRIVE or REVERSE. The noise will increase with engine RPM.

Transmission Abbreviations

A/C: Air Conditioning

AC: Alternating Current

AT: Automatic Transmission

CCDIC: Climate Control Driver Information Center

DC: Direct Current

DIC: Driver Information Center

DLC: Diagnostic Link Connector

DMM: Digital Multimeter

DTC: Diagnostic Trouble Code

EBTCM: Electronic Brake/Traction Control Module

ECCC: Electronically-Controlled Capacity Clutch

ECT: Engine Coolant Temperature

EMI: Electromagnetic Interference

IAT: Intake Air Temperature

IGN: Ignition

IMS: Internal Mode Switch

ISS: Input Speed Sensor

MAP: Manifold Absolute Pressure

MIL: Malfunction Indicator Lamp

NC: Normally Closed

NO: Normally Open

OBD: On Board Diagnostic

OSS: . Output Speed Sensor

PC: Pressure Control

PCM: Powertrain Control Module

PWM: Pulse Width Modulation

RPM: Revolutions Per Minute

SS: Shift Solenoid

STL: Service Transmission Lamp

TAP: Transmission Adaptive Pressure

TCC: Torque Converter Clutch

TCM: Transmission Control Module

TFP: Transmission Fluid Pressure

TFT: Transmission Fluid Temperature

TP: Throttle Position

TV: Throttle Valve

VCM: Vehicle Control Module

VSS: Vehicle Speed Sensor

WOT: Wide Open Throttle

Transmission General Description

The 4L80-E is a fully automatic rear wheel drive electronically controlled transmission. The 4L80-E provides four forward ranges including overdrive and reverse. A gear type of oil pump controls shift points. The PCM and the pressure control (PC) solenoid (force motor) regulate these shift points. The PCM also controls shift schedules and TCC apply rates. Transmission temperature also influences shift schedules and TCC apply rates.

You can operate the transmission in any one of the following seven modes

1. P - PARK position prevents the vehicle from rolling either forward or backward on vehicles less than 15,000 G.V.W. For safety reasons, use the parking brake in addition to the park position.
2. R - REVERSE allows the vehicle to be operated in a rearward direction.
3. N - NEUTRAL allows the engine to be started and operated while driving the vehicle. If necessary, you may select this position in order to restart the engine with the vehicle moving.
4. OD - OVERDRIVE is used for all normal driving conditions. Overdrive provides four gear ratios plus a converter clutch operation. Depress the accelerator in order to downshift for safe passing.
5. D - DRIVE position is used for city traffic, and hilly terrain. Drive provides three gear ranges. Depress the accelerator in order to downshift.
6. 2 - Manual SECOND provides acceleration and engine braking or greater traction from a stop. When you choose manual SECOND, the vehicle will start out in first gear and upshift to second gear. You may select this gear at a vehicle speed of up to 22 km/h (35 mph).
7. 1 - Manual LOW provides maximum engine braking. You may select this gear at a vehicle speed of up to 13 km/h (20 mph).

Transmission Component and System Description

The mechanical components of this unit are as follows

1. A torque converter with a torque converter clutch (TCC)
2. A gear type oil pump
3. Five multiple disk clutches
4. Two band assemblies
5. Three planetary gear sets
6. One sprag clutch
7. Two roller clutches
8. A control valve body assembly

The electrical components of this unit are as follows

1. Two shift solenoid valves, 1 -2 and 2-3
2. A torque converter clutch (TCC) solenoid valve
3. A transmission pressure control (PC) solenoid valve
4. An automatic transmission fluid temperature (TFT) sensor
5. An automatic transmission fluid pressure (TFP) manual valve position switch assembly
6. An output speed sensor (OSS)
7. An input speed sensor (ISS)

For more information refer to Electronic Component Description .

Transmission Adaptive Functions

The 4L80-E transmission uses a line pressure control system that has the ability to adapt line pressure to compensate for normal wear of the following parts

1. The clutch fiber plates
2. The springs and seals
3. The apply bands

This adaptive feature is similar to the fuel and idle control systems, where the PCM has the ability to learn and adjust for monitored system changes.

The PCM maintains information for the following transmission adaptive systems

1-2, 2-3, 3-4 Upshift Adapts - The PCM monitors the automatic transmission input shaft speed sensor (ISS) and the output speed sensor (OSS), to determine when the transmission has started, and completed an upshift. The PCM looks at the time from the beginning, until the completion of the upshift. If the time of the upshift was longer than a calibrated value, then the PCM will adjust the current to the transmission pressure control (PC) solenoid to increase line pressure for the next, same, upshift under identical conditions. If the time of the upshift was shorter than a calibrated value, then the PCM will adjust the current, to the transmission PC solenoid, to decrease line pressure for the next, same, upshift under identical conditions.

Steady State Adapts - Diesel only - The PCM monitors the automatic transmission input shaft speed sensor (ISS) and the output speed sensor (OSS) after a shift has occurred, to determine the amount of clutch slippage in the transmission. If to much slippage is detected, the PCM adjusts the current, to the transmission PC solenoid, to increase the line pressure and reduce clutch slip.

Clearing Transmission Adaptive Pressure (TAP)

Transmission adaptive pressure (TAP) information is displayed and may be reset using a scan tool. The adapt function is a feature of the PCM that either adds or subtracts line pressure from a calibrated base line pressure in order to compensate for normal transmission wear. The TAP information is divided into 13 units, called cells. The cells are numbered 4 through 16. Each cell represents a given torque range. TAP cell 4 is the lowest adaptable torque range and TAP cell 16 is the highest adaptable torque range. It is normal for TAP cell values to display zero or negative numbers. This indicates that the PCM has adjusted line pressure at or below the calibrated base line pressure.

Updating TAP information is a learning function of the PCM designed to maintain acceptable shift times. It is not recommended that TAP information be reset unless one of the following repairs has been made

1. Transmission overhaul or replacement
2. Repair or replacement of an apply or release component (clutch, band, piston, servo)
3. Repair or replacement of a component or assembly which directly affects line pressure

Resetting the TAP values using a scan tool will erase all learned values in all cells. As a result, the PCM will need to relearn TAP values. Transmission performance may be affected as new TAPs are learned. Learning can only take place when the PCM has determined that an acceptable shift has occurred. The PCM must also relearn TAP values if it is replaced.

Scheme 943

The PCM energizes the torque converter clutch pulse width modulated (TCC PWM) solenoid valve, which is located on the transmission valve body. The TCC PWM solenoid valve acts on the TCC apply valve in order to control the torque converter clutch application.

The TCC PWM solenoid valve is pulse width modulated by the PCM. This means that the PCM pulses the solenoid so that the hydraulic pressure against the torque converter clutch modulates. This modulated pressure allows the TCC to slip slightly, thus keeping the TCC balanced just at the point of engagement.

One diagnostic code is associated with the TCC PWM solenoid valve Code P1860, TCC solenoid circuit-electrical, detects a fault in the TCC circuit. While Code P1860 is set, both fourth gear in hot mode and the TCC are inhibited. Shift adapts do not update and the MIL illuminates. Recovery can occur on the next ignition cycle.

Scheme 944

The pressure control (PC) solenoid valve is attached to the valve body. The valve controls line pressure by moving a pressure regulator valve against spring pressure. The PC solenoid valve takes the place of the throttle valve or the vacuum modulator, which was used on past model transmissions.

The PCM varies line pressure based on engine load. Engine load is calculated from various inputs, especially the TP sensor switch. Line pressure is actually varied by changing the amperage applied to the PC solenoid valve from 0 amps, high pressure, to 1.1 amps, low pressure. The PC solenoid valve current is periodically pulsed in order to prevent contamination from sticking the pressure regulator valve.

One diagnostic code is associated with the PC solenoid valve. Code P0748 sets when the PCM detects a difference of 0.16 amp or more between the amperage commanded and actual amperage. While the code is set, the PC solenoid valve turns OFF. Recovery can occur after the next ignition cycle. Code P0748 does not sense a hydraulic problem such as a stuck valve.

Scheme 945

The 1-2 shift solenoid (SS) valve is a normally open exhaust valve that is attached to the valve body. The PCM controls the solenoid by grounding the solenoid through an internal quad driver. The 1-2 SS valve is ON in FIRST and FOURTH gear. When commanded ON, the 1-2 SS valve redirects fluid to act on the 1 -2 shift valve.

There are two PCM related diagnostic trouble codes (DTCs) associated with the 1-2 SS valve: P0751 and P0753.

The PCM monitors the 1-2 SS circuit for an open or short to ground condition. If the PCM detects an open or short to ground condition, then DTC P0753 sets. If the PCM detects an incorrect gear ratio, then DTC P0751 sets. When DTC P0753 or P0751 sets, the PCM commands maximum line pressure, freezes shift adapts from being updated, and inhibits 3-2 downshifts.

Scheme 946

The 2-3 shift solenoid (SS) valve is a normally open exhaust valve that is attached to the valve body. The PCM controls the solenoid by grounding the solenoid through an internal quad driver. The 2-3 SS valve is ON in THIRD and FOURTH gear. When commanded ON, the 2-3 SS valve redirects fluid to act on the 2-3 shift valve.

There are two PCM related diagnostic trouble codes (DTCs) associated with the 2-3 SS valve: P0756 and P0758.

The PCM monitors the 2-3 SS circuit for an open or short to ground condition. If the PCM detects an open or short to ground condition, then DTC P0758 sets. If the PCM detects an incorrect gear ratio, then DTC P0756 sets. When DTC P0758 or P0756 sets, the PCM commands maximum line pressure, freezes shift adapts from being updated, and inhibits 3-2 downshifts.

Scheme 947

A gear range sensing device call an automatic transmission fluid pressure (TFP) manual valve position switch assembly is used by the PCM in order to sense which gear range has been selected by the vehicle operator. The TFP manual valve position switch assembly is located on the valve body, and consists of five pressure switches combined into one unit. The PCM applies system voltage to the TFP manual valve position switch assembly on three separate wires. These three circuits are either grounded or open, depending on which gear range has been selected, and on which combination of the five switches gave pressure applied to them.

When the vehicle is in PARK, with the key ON and the engine OFF, the normal state of the TFP manual valve position switch assembly will be DRIVE 2. When the key is ON and the engine is running, the normal state of the TFP manual valve position switch assembly is in PARK/NEUTRAL.

There are two possible combinations of the switches within the pressure switch manifold that do not represent an actual gear range. If the PCM detects either of these combinations, then a diagnostic trouble code (DTC) sets.

The PCM TFP DTC P1810 sets when the TFP switch indicates the following

1. An illegal gear range
2. DRIVE4, DRIVE2 or REVERSE position before and after start-up
3. PARK/NEUTRAL with a ratio greater than 1.05
4. REVERSE with ratio indicating outside of REVERSE
5. DRIVE4, DRIVE3, DRIVE2 or DRIVE1 with ratio indicating REVERSE

While DTC P1810 is present, the PCM assumes DRIVE4 for shift pattern, sets line pressure to maximum, freezes shift adapts, and forces TCC ON with 4th gear commanded.

Scheme 948

Scheme 949

Both of the automatic transmission input shaft speed (AT ISS) and the automatic transmission output shaft speed (AT OSS) sensors are magnetic induction sensors. The input and the output sensors are accessible from the left hand side of the transmission. The AT ISS sensor is located just forward of center and the AT OSS sensor is located near the rear. A voltage signal is induced in the AT ISS sensor by serrations, which are cut in the outside diameter of the forward clutch housing. Voltage is induced in the output sensor by gear teeth, which are pressed on the outside diameter of the rear carrier assembly.

Scheme 950

The PCM used speed information from these sensors in order to determine the following

1. Whether the engine is running
2. Vehicle speed
3. Calculation of the gear ratio
4. Calculation of TCC slip
5. Calculation of turbine speed

Code P0502 and P0503 set if a fault exists in the AT OSS sensor circuit, and the PCM calculates a default value using the AT ISS sensor values. As long as the fault remains, and the code is set, the PCM also commands maximum line pressure, freeze shift adapts, and the MIL illuminates. If the fault is removed, normal operation resumes after the next ignition cycle.

Scheme 951

The automatic transmission fluid temperature (TFT) sensor assembly is a thermistor which is mounted in the wiring harness assembly. Low transmission temperature produces high resistance, while high temperature produces low resistance. The PCM supplies a 5-volt signal to the TFT sensor assembly through an internal resistor. Then the PCM measures the voltage drop in the circuit. Voltage is high when the transmission is cold and low when the transmission is hot.

The PCM uses the TFT sensor assembly in order to regulate torque converter clutch apply, as well as shift quality.

DTCs P0711, P0712 and P0713 indicate a fault in the TFT Sensor Assembly circuit. After the vehicle has been started, transmission temperature should rise steadily and stabilize between 90-115°C (194-239°F), depending on load. All three DTCs causes the PCM to use a default value of 140°C (284°F), thus reacting as if the transmission were hot in either case. When DTCs P0711, P0712 or P0713 are set, the PCM freezes the shift adapts from being updated, and the MIL illuminates. Some driveability symptoms will be noticed, especially when cold.

Scheme 952

The transmission range (TR) switch is part of the park/neutral position (PNP) and backup lamp switch assembly, which is externally mounted on the transmission manual shaft. The TR switch contains four internal switches that indicate the transmission gear range selector lever position. The PCM supplies ignition voltage to each switch circuit. As the gear range selector lever is moved, the state of each switch may change, causing the circuit to open or close. An open circuit or switch indicates a high voltage signal. A closed circuit or switch indicates a low voltage signal. The PCM detects the selected gear range by deciphering the combination of the voltage signals. The PCM compares the actual voltage combination of the switch signals to a TR switch combination chart stored in memory.

Scheme 953

The transmission electrical connector is an important part of the transmission operating system. Any interference with the electrical connection can cause the transmission to set diagnostic trouble codes or affect proper operation.

The following items can affect the electrical connection

1. Bent pins in the connector from rough handling during connection and disconnection
2. Wires backing away from the pins or coming uncrimped, in either the internal or the external wiring harness
3. Dirt contamination entering the connector when disconnected
4. Pins in the internal wiring connector backing out of the connector or pushed out of the connector during reconnection
5. Transmission fluid leaking into the connector, wicking up into the external wiring harness and degrading the wire insulation
6. Moisture intrusion in the connector
7. Low pin retention in the external connector from excessive connection and disconnection of the wiring connector assembly
8. Pin corrosion from contamination
9. Damaged connector assembly

Remember the following points

1. In order to remove the connector, squeeze the two tabs toward each other and pull straight up without pulling by the wires.
2. Limit twisting or wiggling the connector during removal. Bent pins can occur.
3. Do not pry the connector off with a screwdriver or other tool.
4. Visually inspect the seals to ensure that they are not damaged during handling.
5. In order to reinstall the external wiring connector, first orient the pins by lining up the arrows on each half of the connector. Push the connector straight down into the transmission without twisting or angling the mating parts.
6. The connector should click into place with a positive feel and/or noise.
7. Whenever the transmission external wiring connector is disconnected from the internal harness and the engine is operating, DTCs will set. Clear these DTCs after reconnecting the external connector.

Scheme 954

Scheme 955

Scheme 956

Scheme 957

See also:
• DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS
• ENGINE FLYWHEEL CLEANING AND INSPECTION
• KNEE BOLSTER REPLACEMENT - LEFT
• KNEE BOLSTER BRACKET REPLACEMENT - LEFT
• FASTENER NOTICE
• ENGINE COVER REPLACEMENT
• GRILLE REPLACEMENT (UPLEVEL)
• PROPELLER SHAFT REPLACEMENT - ONE PIECE
• TRANSMISSION SUPPORT REPLACEMENT
• BATTERY DISCONNECT CAUTION
• TRANSFER CASE
• CATALYTIC CONVERTER REPLACEMENT (4.3L)
• STARTER MOTOR REPLACEMENT (4.8L, 5.3L & 6.0L)
• STARTER MOTOR REPLACEMENT (4.3L)
• Transmission Fluid Temperature (TFT) Sensor Specifications
• Transmission Component and System Description
• Symptoms - Automatic Transmission
• Transmission Range Switch Logic
• Shift Solenoid Valve State and Gear Ratio
• Transmission Fluid Pressure (TFP) Manual Valve Position Switch Logic
• Line Pressure
• Transmission Fluid Checking Procedure
• Transmission Scan Tool Data List
• Torque Converter Diagnosis Procedure
• Flexplate/Torque Converter Vibration Test
• Noise and Vibration Analysis
• Valve Body and Pressure Switch Replacement
• Fluid Capacity Specifications
• Park/Neutral Position Switch Replacement
• Automatic Transmission Oil Cooler Flushing and Flow Test (J 35944-A)