Automatic Transmission - 4L80-E/4L85-E (Service & Replacement): Overview GMC Savana H2500

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.

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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.

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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.

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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.

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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.

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Scheme 660

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).

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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.

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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.

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Scheme 669

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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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Scheme 702

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.

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Scheme 704

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.

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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.

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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.

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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.

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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.

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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.

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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.

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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 .