Automatic Transaxle Diagnosis - 4t80-e Cadillac DeVille Concours I final

APPLICATION

HYDRA-MATIC 4T80-E TRANSAXLE APPLICATIONS

DESCRIPTION & OPERATION

The Hydra-Matic 4T80-E transaxle uses 2 electric solenoids to control transaxle upshifts and downshifts. Transaxles also use a pressure control (force motor) solenoid to control line pressure, Transaxle Fluid Temperature (TFT) sensor, pressure switch assembly (also referred to as Transaxle Fluid Pressure (TFP) valve position switch), Vehicle Speed Sensor (VSS), Input Speed Sensor (ISS), and a lock-up control solenoid for Torque Converter Clutch (TCC) operation. Each solenoid is turned on or off by the Powertrain Control Module (PCM). PCM also includes on-board self-diagnostics. This helps identify which parts or circuits may need further testing.

Each solenoid either holds hydraulic pressure (solenoid on) or releases hydraulic pressure (solenoid off). This action controls shift valves inside valve body. By switching one or both solenoids on or off, different combinations of clutches, sprags and bands are operated. See CLUTCH & BAND APPLICATION (4T80-E) table under CIRCUIT TESTS.

PCM

On Cadillac models, PCM is located in left front corner of engine compartment under air cleaner housing. On Aurora, PCM is located behind right side sound insulator, under instrument panel.

PCM controls ignition, fuel and emission devices related to engine and transaxle upshifts and downshifts. PCM receives electronic signals from sensors and switches. These signals help PCM determine when to operate various relays and solenoids related to engine and transaxle control.

SENSORS & SWITCHES

PCM controls converter clutch lock-up, upshifts and downshifts based on transaxle fluid temperature, system voltage, throttle position, transaxle fluid pressure switches, vehicle speed sensor and input speed sensor. (Scheme 95) System also includes several other switches and sensors which are used for engine control. These components are covered in ENGINE PERFORMANCE.

1-2 & 2-3 Shift Solenoids

Transaxle is shifted up or down by 2 electric shift solenoids. Both solenoids are located on valve body. (Scheme 95) Ignition power is supplied to each solenoid by transaxle fuse. 1-2 solenoid controls hydraulic pressure to 1-2 and 3-4 shift valves. 2-3 solenoid controls hydraulic pressure to 1-2 and 2-3 shift valves.

Pressure Control Solenoid

Pressure control (force motor) solenoid has a spool valve and operates pressure regulator valve. (Scheme 95) PCM sends a frequency signal to pressure control solenoid to regulate hydraulic line pressure. Frequency signal (duty cycle) is measured with a dwell meter or lab scope. When duty cycle is zero, line pressure is at maximum, and pressure control solenoid draws zero amps. When duty cycle is 60 percent, line pressure is at minimum, and pressure control solenoid draws 1.1 amps at 4.5 volts.

TCC Solenoid

This solenoid uses a negative duty cycle and Pulse Width Modulation (PWM) to control TCC apply valve. PCM sends a frequency signal to TCC solenoid to gradually apply or release TCC. (Scheme 95)

Scheme 95

LIMP-IN MODE

If sensor input signals are missing or inadequate for transmission operation, PCM will output preset operating signals to transmission. This mode will keep vehicle operational and allow it to be driven with reduced transmission function and performance, to a repair facility. Malfunction Indicator Light (MIL) will light if malfunction occurs. Vehicle should not be driven for extended periods in limp-in mode.

SELF-DIAGNOSTIC SYSTEM

PCM constantly monitors all electrical circuits. If PCM detects circuit problems or sensors out of range, it will record a Diagnostic Trouble Code (DTC). If problem continues for a predetermined time, Malfunction Indicator Light (MIL) will glow.

If MIL is on all the time, DTC(s) are currently being detected. If MIL is off, but PCM had detected a circuit or sensor problem, DTC(s) will be stored in computer memory.

Stored DTCs may be retrieved from PCM memory using a scan tool. DTCs CANNOT be retrieved by grounding 16-pin Data Link Connector (DLC).

Note. Faulty engine sensors and actuators may cause transaxle related DTCs or driveability problems. Engine faults and related DTCs must be diagnosed and repaired before transaxle codes are repaired. For additional information on diagnosing and repairing engine related PCM trouble codes, see appropriate SELF-DIAGNOSTIC article in ENGINE PERFORMANCE.

COMPONENT & WIRING HARNESS RESISTANCE CHECK

1. Install Jumper Harness (J-39775) to transaxle 20-pin connector. Using an ohmmeter, measure resistance between specified terminals for each component. (Scheme 96) Compare resistance reading to known values. See «TRANSAXLE COMPONENT RESISTANCE SPECIFICATIONS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) table.
2. If resistance reading is okay, go to next step. If resistance reading is not okay, disconnect wiring harness at component and measure component resistance. Replace component if resistance is not as specified. If resistance is as specified, repair wiring harness between component and 20-pin connector.
3. Measure resistance between ground and each terminal at transaxle 20-pin connector. (Scheme 96) Resistance should be more than 250 k/ohms for each component. If resistance is within specification, problem is intermittent. If resistance is low, disconnect wiring harness at component.
4. Measure resistance between component terminals and ground. If resistance is low, replace component. If resistance is high, inspect wiring harness for short to ground. Repair as necessary.

TRANSAXLE COMPONENT RESISTANCE SPECIFICATIONS

Note. Pressure switch assembly is also referred to as Transaxle Fluid Pressure (TFP) valve position switch.

PRESSURE SWITCH ASSEMBLY

1. Install Jumper Harness (J-39775) to transaxle 20-pin connector. Using DVOM, measure resistance between terminal "N" of 20-pin connector and ground. (Scheme 96) If resistance is more than 1000 ohms, go to next step. If resistance is less than 1000 ohms, inspect and repair range "A" circuit between TFP valve position switch and 20-pin connector, then go to step 7. See «WIRING DIAGRAMS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e). If circuit is okay, replace TFP valve position switch, then go to step 7.
2. Measure resistance between terminal "R" of 20-pin connector and ground. If resistance is more than 1000 ohms, go to next step. If resistance is less than 1000 ohms, inspect and repair range "B" circuit between TFP valve position switch and 20-pin connector, then go to step 7. See «WIRING DIAGRAMS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e). If circuit is okay, replace TFP valve position switch, then go to step 7.
3. Measure resistance between terminal "P" of 20-pin connector and ground. If resistance is more than 1000 ohms, go to next step. If resistance is less than 1000 ohms, inspect and repair range "C" circuit between TFP valve position switch and 20-pin connector, then go to step 7. See «WIRING DIAGRAMS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e). If circuit is okay, replace TFP valve position switch, then go to step 7.
4. Start engine and allow to idle. Place gear selector in "R" position. Measure resistance between terminal "N" of 20-pin connector and ground. If resistance is more than 5 ohms, go to next step. If resistance is less than 5 ohms, inspect and repair range "A" circuit between TFP valve position switch and 20-pin connector, then go to step 7. If circuit is okay, replace TFP valve position switch, then go to step 7.
5. Measure resistance between terminal "R" of 20-pin connector and ground. If resistance is more than 5 ohms, go to next step. If resistance is less than 5 ohms, inspect and repair range "B" circuit between TFP valve position switch and 20-pin connector, then go to step 7. If circuit is okay, replace TFP valve position switch, then go to step 7.
6. Shift gear selector to "D4". Measure resistance between terminal "P" of 20-pin connector and ground. If resistance is more than 5 ohms, replace TFP valve position switch, then go to next step. If resistance is less than 5 ohms, inspect and repair range "C" circuit between TFP valve position switch and 20-pin connector, then go to next step. If circuit is okay, replace TFP valve position switch, then go to next step.
7. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Test drive vehicle. Ensure transaxle upshifts and downshifts correctly. Select SPECIFIC DTC and enter DTC "P1810". If DTC P1810 is not present, repair is complete. If DTC P1810 is still present, go to step 24 of DTC P1810 under «DIAGNOSTIC TESTS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e__diagnostic-tests).

4T80-E CLUTCH & BAND APPLICATION

SHIFT MODE SWITCH (AURORA)

Note. Shift mode switch (Aurora) and traction control off switch (Cadillac) do not set a DTC. However, the following diagnostic tests are included as these components may affect transaxle performance.

Circuit Description

Shift mode switch (driver select shift switch) is located on gear selector lever. Switch enables driver to select a more aggressive shift pattern within mid range throttle position (40-80 percent). Depressing switch provides a ground path for ignition voltage from PCM. While PCM is in performance (POWER) mode, shifts are firmer and slightly delayed (about 1-3 MPH). Return to NORMAL mode by depressing switch a second time.

Diagnostic Procedure

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Select A/T PERFORMANCE MODE on scan tool. While depressing shift mode switch, observe scan tool display. If scan tool indicates normal and performance with switch in appropriate position, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e__diagnostic-aids) . If scan tool does not indicate normal and performance with switch in appropriate position, go to next step.
2. Place shift mode switch in normal mode. If scan tool does not indicate normal mode, go to next step. If scan tool indicates normal mode, go to step 4 .
3. Disconnect shift mode switch connector. If scan tool does not indicate performance mode, replace shift mode switch, then go to step 8 . If scan tool indicates performance mode, go to step 6 .
4. Disconnect shift mode switch connector. Connect fused jumper between ground and transaxle 20-pin connector terminal "A". If scan tool does not indicate performance mode, go to next step. If scan tool indicates performance mode, go to step 7 .
5. Check for open in Dark Blue wire between PCM connector and shift mode switch. Repair as necessary, then go to step 8 . If wire is okay, replace PCM, then go to step 8 .
6. Check for short to ground in Dark Blue wire between PCM connector and shift mode switch. Repair as necessary, then go to step 8 . If wire is okay, replace PCM, then go to next step 8 .
7. Check for open in Black wire between ground and shift mode switch. Repair as necessary, then go to next step. If wire is okay, replace shift mode switch, then go to next step.
8. After repair is complete, road test vehicle. Record the following snapshot data: pressure control solenoid duty cycle and throttle angle with switch in normal mode, and pressure control solenoid duty cycle and throttle angle with switch in performance mode. Observe MPH and pressure control duty cycle with switch in both modes. Compare vehicle speed and pressure control duty cycle with switch in both modes. If values are different in each mode, system is okay. If values are the same, repeat test.

Diagnostic Aids

If increased performance is not evident when in POWER mode, use snapshot function on scan tool to diagnose. Record data with vehicle in normal mode, then in performance mode. Review data sets for differences in following items: pressure control solenoid duty cycle, vehicle speed and commanded gear.

Traction control (TRAC) off switch is located in the glove box. This switch allows driver to select 2nd gear starts. Select a 2nd gear start if vehicle is stuck in snow, sand or on ice. Switch is a momentary contact switch. Depressing switch creates a ground path for Electronic Brake and Traction Control Module (EBTCM) ignition voltage input. When EBTCM senses this voltage drop, module turns off traction control. EBTCM sends a serial data message to Platform Zone Module (PZM). This module is part of the body control system. PZM sends a serial data message to PCM. PCM commands a 2nd gear start for that ignition cycle. Following this and every ignition cycle, traction control returns to an active state. Transaxle again performs a 1st gear start.

Driver Information Center (DIC) information button is located on instrument panel. Pressing information button displays traction control state. When DIC displays TRACTION READY, vehicle performs a 1st gear start. When DIC displays TRACTION OFF, vehicle performs 2nd gear start. DIC will not update traction status display when traction control switch is pushed and a scan tool is installed. After removing scan tool, ignition must be cycled in order to update DIC.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Select CHASSIS DTC on scan tool. If there are any Anti-Lock Brake System (ABS) or Traction Control System (TCS) DTCs present, diagnose these DTCs first. If there are not any ABS or TCS DTCs present, go to next step.
2. Select MORE DATA LIST, 1ST GR START on scan tool. While depressing traction control switch, observe scan tool. If current gear display indicates either 1 or 2 when switch is depressed, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) . If current gear display does not indicate either 1 or 2 when switch is depressed, go to next step.
3. Disconnect traction control switch connector. Connect a fused jumper between connector terminals. See «WIRING DIAGRAMS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) . If current gear display changes, replace traction control switch, then go to step 6 . If current gear display does not change, go to next step.
4. Connect fused jumper between a known good ground and Brown/White wire on DeVille and Eldorado or Light Blue wire on Seville at traction control switch connector. If current gear display does not change, go to next step. If current gear display changes, check for open, short to voltage or short to ground in Black/White wire between traction control switch and ground. See «WIRING DIAGRAMS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) . Repair as necessary, then go to step 6 . If wire is okay, problem exists within body control (Platform Zone Module) system. Refer to appropriate BODY CONTROL MODULE article in ACCESSORIES & EQUIPMENT.
5. Check for open, short to voltage or short to ground in Brown/White wire on DeVille and Eldorado or Light Blue wire on Seville between Electronic Brake Traction Control Module (EBTCM) or Instrument Panel Integration Module (IPM) and traction control switch. Repair as necessary, then go to next step. If wire is okay, problem exists within body control (Platform Zone Module) system. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
6. After repair is complete, road test vehicle. Press traction control switch in order to command 1st gear start. Drive vehicle and note acceleration and performance. Stop vehicle and press switch again in order to command 2nd gear start. Drive vehicle and note acceleration and performance. If there is a difference in acceleration and performance in each switch position, system is okay. If there is not a difference, repeat test.

If in TRACTION OFF mode and vehicle does not perform a 2nd gear start, using scan tool, select 1st gear. Observe current gear status on data list. Press traction control switch once and observe scan tool display. Scan tool should indicate 1 or 2, depending on last switch input. When diagnosing for an intermittent short or open condition, move wiring harness while observing scan tool for value change.

NO MALFUNCTION INDICATOR LIGHT (MIL)

If Malfunction Indicator Light (MIL) does not light, see MIL INOPERATIVE or MIL CIRCUIT CHECK under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.

NO DATA LINK CONNECTOR (DLC) DATA

If scan tool does not display PCM data, see DLC DIAGNOSIS OR NO SCAN TOOL DATA under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.

DIAGNOSIS & TESTING

Note. To test electronic control of transaxle solenoids, sensors, pressure switch assembly and wiring harness without using self-diagnostics function or if self-diagnostics function does not work, go to CIRCUIT TESTS . After repairs are made, DTCs should be erased from computer memory. See CLEARING DIAGNOSTIC TROUBLE CODES .

Note. If no DTCs are present and vehicle is in limp-in mode, check fused power supply circuit to transaxle solenoids. Non-related transaxle component system failure may cause this circuit fuse to fail. Fuses such as IGN 1 or SHIFT SOL fuse supply power to non-related transaxle components (ABS, HO2S or EVAP system) which may have caused fuse to fail.

Note. Trouble codes will be recorded at various operating times. Some codes require operation of affected sensor or switch for 5 seconds; others may require operation for 5 minutes or longer at normal operating temperature, road speed and load. Therefore, some codes may not set in a service bay operational mode and may require road testing vehicle in order to duplicate condition under which code will set.

ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK

Note. Use of scan tool is required to perform OBD system check. Perform this test prior to performing any diagnostic procedures in DTC tests.

Note. Most problems that exist with the MIL or diagnostic system are engine performance or PCM related. Procedures for repairing these systems and circuits may require additional engine performance repair data. This test contains references to additional procedures not found in this publication.

The OBD System Check Determines The Following

1. If Malfunction Indicator Light (MIL) works.
2. If PCM is operating and can recognize a fault.
3. If any codes are stored.

OBD system check is the starting point for utilizing the self-diagnostic system for determining computer-related problems. After performing necessary tests as described in diagnostic system check, if no codes are indicated and driveability problems still exist, see appropriate TROUBLE SHOOTING - NO CODES article in ENGINE PERFORMANCE.

Note. The following steps should be performed first to reduce diagnostic time and prevent replacement of good parts.

1. Check for one or more of the following conditions: MIL illuminates with engine running. Performance/driveability concern. Suspected fault in powertrain component or system. If one or more of the listed conditions are present, go to next step. If none of the listed conditions are present, system is okay.
2. Ensure battery is fully charged. Turn ignition off. Connect scan tool. Turn ignition on. If scan tool displays PCM data, go to next step. If scan tool does not display PCM data, go to «NO DATA LINK CONNECTOR (DLC) DATA»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e__no-data-link-connector-dlc-data) .
3. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and stalls, go to NO START DIAGNOSIS in appropriate BASIC DIAGNOSTIC PROCEDURES article in ENGINE PERFORMANCE.
4. Using scan tool, observe DTC status for MIL REQUEST, FAIL THIS IGN, LAST TEST FAIL and HISTORY. If any DTCs are stored, save freeze frame and failure records information using scan tool CAPTURE INFO feature. Diagnose DTCs. See DIAGNOSTIC TESTS in appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. If DTCs are not present, go to next step.
5. Compare PCM data values displayed on scan tool with typical control system data values. If values are within limits, system is okay. If values are not within limits, see appropriate SYSTEM & COMPONENT TESTING article in ENGINE PERFORMANCE.

If serial data communications is lost while engine is running, check system voltage. A system voltage that is not 9-16 volts may cause a loss of serial data transmission. Diagnose charging system. Inspect all related wiring and connections including connections at PCM. These may cause an intermittent malfunction. Check for damaged, corroded or pushed out terminals.

RETRIEVING DIAGNOSTIC TROUBLE CODES

Note. Stored DTCs may be retrieved from PCM memory using a scan tool. DTCs CANNOT be retrieved by grounding 16-pin Data Link Connector (DLC). Plugging scan tool into DLC, located under left side of instrument panel, enables user to read DTCs and check voltages in system on serial data line.

Scan tools may also furnish information on status of output devices (solenoids and relays). However, status parameters are only an indication that output signals have been sent to devices by control module; they do not indicate if devices have responded properly to signal. Check for proper response at output device using a voltmeter or test light.

If trouble codes are not present, this is not necessarily an indication a problem does not exist. Driveability related problems with codes displayed occur about 20 percent of the time, while driveability problems without codes occur about 80 percent of the time. Sensors that are out of specification WILL NOT set a trouble code but WILL cause driveability problems. Using scan tool is the easiest method of checking sensor specifications and other data parameters. Scan tool is also useful in finding intermittent wiring problems by wiggling wiring harness and connections (key on, engine off) while observing scan tool.

DIAGNOSTIC TROUBLE CODE DEFINITIONS

Note. Only transaxle-related trouble codes are listed. For engine related DTC definitions, see TROUBLE CODE DEFINITIONS article in APPLICATIONS & IDENTIFICATION. For engine related DTC diagnosis, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. These DTCs pertain to engine performance and must be repaired first, as engine performance and related component signals will affect transaxle operation and diagnosis.

DIAGNOSTIC TROUBLE CODE DEFINITIONS

CLEARING DIAGNOSTIC TROUBLE CODES

DTCs can be cleared using scan tool. If scan tool is not available, turn ignition switch to OFF position. Remove PCM fuse from fuse block for 30 seconds. Replace fuse. If fuse cannot be located, disconnect PCM pigtail at battery for 30 seconds. DTCs may also be cleared by disconnecting negative battery cable. However, this may result in loss of other on-board memory data, such as preset radio tuning. After power to PCM is removed, poor driveability may occur until control module "relearns" operating parameters.

DTCs will also be cleared under the following conditions: PCM will turn off MIL after 3 consecutive ignition cycles without a failure reported. PCM will cancel DTC default actions when fault no longer exists and ignition is cycled off long enough to power down PCM. DTC will be cleared when vehicle has achieved 40 warm-up cycles without a failure reported.

HARD OR INTERMITTENT TROUBLE CODE DETERMINATION

During any diagnostic procedure, it must be determined if codes are hard failure codes or intermittent failure codes. Diagnostic tests will not usually help analyze intermittent codes. To determine hard codes and intermittent codes, proceed as follows

1. Enter diagnostic mode. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e__retrieving-diagnostic-trouble-codes) . Read and record all stored DTCs. Exit diagnostic mode and clear trouble codes. See «CLEARING DIAGNOSTIC TROUBLE CODES»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e__clearing-diagnostic-trouble-codes) .
2. Apply parking brake and place transaxle in Neutral or Park. Block drive wheels and start engine. MIL should go out. Run warm engine at specified curb idle for 2 minutes and note MIL.
3. If MIL comes on, enter diagnostic mode. Read and record DTCs. This will reveal hard failure codes. DTCs may require a road test to reset hard failure after clearing DTCs. If MIL does not come on, all stored DTCs were intermittent failures.

CONNECTOR IDENTIFICATION

Note. For connector identification, refer to illustrations. (Scheme 96)- (Scheme 98)

Scheme 96

Scheme 97

Scheme 98

Diagnostic Tests

Following diagnostic tests are DTC specific. Always perform On-Board Diagnostic (OBD) System Check prior to performing any diagnostic procedure. For PCM terminal locations (Scheme 97)and (Scheme 98). See WIRING DIAGRAMS. For engine related DTCs, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE

Diagnostic aids located at end of each diagnostic test, are additional tips used to help diagnose trouble codes when diagnostic procedures do not find a problem.

DTC P0218: TRANSAXLE FLUID OVERHEATING

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS . For fluid circuit identification, see OIL CIRCUIT DIAGRAMS in section No. 1.

Transaxle Fluid Temperature (TFT) sensor is a negative coefficient thermistor. When transaxle fluid is cold, sensor resistance is high. As transaxle temperature warms up, sensor resistance lowers. PCM uses TFT information to control TCC apply and release, line pressure and shift timing. TFT range is from -40 to 305°F (-40 to 151°C). DTC P0218 is set if PCM detects a high transaxle fluid temperature for an extended period of time on TFT sensor circuit. IDLE ENGINE TRANSMISSION HOT message will display on Driver Information Center (DIC).

Conditions For Setting DTC P0218

DTC will set under the following conditions

1. DTCs P0116, P0117 or P0118 (engine coolant temperature) are not present.
2. DTCs P0711, P0712 or P0713 (transaxle fluid temperature) are not present.
3. Transaxle fluid temperature is more than 266°F (130°C) for 30 minutes, or 291°F (144°C) for 32 seconds.
4. Engine coolant temperature is more than 32°F (0°C).

Action Taken By PCM

PCM performs the following if DTC is set

1. Will not light MIL when fault is set.
2. DTC P0218 will be stored in PCM history.

1. Ensure transaxle fluid level is correct. DTC P0218 can only be set if one or more of the following conditions exist. Inspect for these conditions: Engine overheating (thermostat and/or restricted radiator) Vehicle overloading Transaxle fluid contaminated with antifreeze Transaxle filter clogged or not seated properly Clogged scavenger screens. Low line pressure (cooler lines clogged or restricted) Repair or replace components as necessary, then go to next step.
2. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Select SPECIFIC DTC and enter DTC "P0218". Turn ignition on for more than 5 seconds. Ensure transaxle fluid temperature stays below 248°F (120°C). If DTC P0218 is not present, repair is complete. If DTC P0218 is still present, repeat test.

Check transaxle and PCM connectors for bent, broken or backed out terminals. Check transaxle cooling system for possible blockage and/or restrictions. Ensure transaxle fluid level is correct.

DTC P0502: VEHICLE SPEED SENSOR CIRCUIT (LOW INPUT)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Vehicle speed is signaled to PCM by Vehicle Speed Sensor (VSS). Sensor is a Permanent Magnet (PM) generator mounted to transaxle case extension. PM generator produces an AC voltage as speed sensor rotor teeth pass sensor's magnetic field. PCM converts AC voltage into digital signal. PCM uses vehicle speed to determine shift timing, TCC apply and release, and gear ratio calculations. VSS voltage will vary from .5 volt AC at 100 RPM to more than 100 volts AC at 8000 RPM. VSS resistance value is 1240-1540 ohms. DTC P0502 is set if PCM detects a low vehicle output speed when vehicle has high engine speed in drive gear.

Conditions For Setting DTC P0502

DTC will set under the following conditions

1. DTCs P0101, P0102 and P0103 (MAF sensor), or P0121, P0122 and P0123 (throttle position sensor) are not present.
2. DTCs P0716 and P0717 (input speed sensor) and P1810 (TFP valve position switch) are not present.
3. Transaxle is not in Park, Neutral or Reverse.
4. Engine speed is more than 2000 RPM.
5. Throttle angle is more than 12.8 degrees.
6. Vehicle speed is 5 MPH or less for 2 seconds.
7. Engine torque is more than 80 ft. lbs. (109 N.m).

PCM performs the following if DTC is set

1. Will light MIL at first failure signal.
2. SERVICE ENGINE SOON, SPEED SENSOR FAULT will be displayed on Driver Information Display (DIC).
3. Inhibits TCC engagement.
4. Defaults to line pressure.
5. Calculates vehicle speed from input speed sensor and commanded gear.
6. Disables cruise control.
7. DTC P0502 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. Raise and support vehicle. CAUTION: To prevent damage to drive axles, support lower control arms in normal horizontal position.
2. Start engine and let idle. Shift gear selector to "D" position. Select "OSS RPM" on scan tool. With drive wheels rotating, if transaxle output speed does not increase when wheel speed increases, go to next step. If transaxle output speed increases when wheel speed increases, cause is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e).
3. Turn ignition off. Disconnect PCM connector C2. Connect voltmeter between VSS terminals at PCM connector C2. (Scheme 98) See «WIRING DIAGRAMS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e). Rotate drive wheels and observe voltmeter display. If voltage is more than.5 volt, go to next step. If voltage is less than.5 volt, go to step 5.
4. Use scan tool to check for most current PCM calibration I.D. number. Refer to manufacturer service bulletins if necessary. If I.D. number matches, replace PCM, then go to step 8. If I.D number does not match, update PCM with latest calibration, then go to step 8.
5. Measure resistance of VSS circuit at PCM connector. Connect ohmmeter between PCM connector C2 terminals No. 7 and 8. If resistance is less than 1540 ohms, go to next step. If resistance is more than 1540 ohms, check for open circuit between VSS and PCM. Repair as necessary, then go to step 8. If open circuit is not found, go to step 7.
6. Check for VSS wires shorted together. Repair wires as necessary, then go to next step. If resistance is more than 1260 ohms, check for short to ground in circuits between VSS and PCM. Repair circuits as necessary, then go to step 8. If wires were not shorted together or shorted to ground, go to next step.
7. Remove VSS from transaxle. Connect ohmmeter between VSS terminals. If resistance is 1260-1540 ohms, replace PCM and go to next step. If resistance is not 1260-1540 ohms, replace VSS, then go to next step.
8. Install VSS into transaxle. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Select SPECIFIC DTC and enter DTC "P0502". Test drive vehicle. If DTC P0502 is not present, repair is complete. If DTC P0502 is still present, repeat test.

Check for Electromagnetic Interferences (EMI) induced on VSS circuits caused by misrouted wires along spark plug wires. Ensure VSS is secured to transaxle case extension. Inspect wiring for poor connections at PCM, VSS and at transaxle 20-pin connector. Check for bent, backed out or broken terminals, or misaligned connectors. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

Vehicle speed is signaled to PCM by Vehicle Speed Sensor (VSS). Sensor is a Permanent Magnet (PM) generator mounted to transaxle case extension. PM generator produces an AC voltage as speed sensor rotor teeth pass sensor's magnetic field. PCM converts AC voltage into digital signal. PCM uses vehicle speed to determine shift timing, TCC apply and release, and gear ratio calculations. VSS voltage will vary from .5 volt AC at 100 RPM to more than 100 volts AC at 8000 RPM. VSS resistance value is 1260-1540 ohms. DTC P0503 is set if PCM detects a large change in vehicle speed.

Conditions For Setting DTC P0503

DTC will set under the following conditions

1. DTCs P0101, P0102 and P0103 (MAF sensor), or P0121, P0122 and P0123 (throttle position sensor) are not present.
2. DTCs P0716 and P0717 (input speed sensor) are not present.
3. Ignition on for more than 2 seconds.
4. Transaxle is not in Park, Neutral or Reverse.
5. DTC P1810 (TFP valve position switch) is not present.
6. Engine run time is more than 5 seconds.
7. Engine is not in fuel shut off mode.
8. Gear selection is more than 3 seconds.
9. Engine speed is more than 500 RPM.
10. Throttle angle is more than 12.8 degrees.
11. Traction control is inactive.
12. Engine torque is more than 80 ft. lbs. (109 N.m).
13. Vehicle speed drops more than 11 MPH in .013 seconds and input speed does not drop 100 RPM within .13 seconds, occurring 10 times in 10 seconds.

PCM performs the following if DTC is set

1. Will light MIL when fault is set.
2. SERVICE ENGINE SOON, SPEED SENSOR FAULT will be displayed on Driver Information Display (DIC).
3. Inhibits TCC engagement.
4. Defaults to line pressure.
5. PCM freezes shift adapts.
6. Calculates vehicle speed from input speed sensor and commanded gear.
7. Disables cruise control.
8. DTC P0503 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. Raise and support vehicle. CAUTION: To prevent damage to drive axles, support lower control arms in normal horizontal position.
2. Start engine and let idle. Shift gear selector to "D" position. Select OSS RPM on scan tool. With drive wheels rotating, if transaxle output speed does not increase when wheel speed increases, go to next step. If transaxle output speed increases when wheel speed increases, cause is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e).
3. Turn ignition off. Disconnect PCM connector C2. Connect voltmeter between VSS terminals at PCM connector C2. (Scheme 98) See «WIRING DIAGRAMS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e). Rotate drive wheels and observe voltmeter display. If voltage is more than.5 volt, go to next step. If voltage is less than.5 volt, go to step 5.
4. Use scan tool to check for most current PCM calibration I.D. number. Refer to manufacturer service bulletins if necessary. If I.D. number matches, replace PCM, then go to step 8. If I.D number does not match, update PCM with latest calibration, then go to step 8.
5. Measure resistance of VSS circuit at PCM connector. Connect ohmmeter between PCM connector C2 terminals No. 7 and 8. If resistance is less than 1540 ohms, go to next step. If resistance is more than 1540 ohms, check for open circuit between VSS and PCM. Repair as necessary, then go to step 8. If open circuit is not found, go to step 7.
6. Check for VSS wires shorted together. Repair wires as necessary, then go to next step. If resistance is more than 1260 ohms, check for short to ground in circuits between VSS and PCM. Repair circuits as necessary, then go to step 8. If wires were not shorted together or shorted to ground, go to next step.
7. Remove VSS from transaxle. Connect ohmmeter between VSS terminals. If resistance is 1260-1540 ohms, replace PCM, then go to next step. If resistance is not 1260-1540 ohms, replace VSS, then go to next step.
8. Install VSS into transaxle. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Select SPECIFIC DTC and enter DTC "P0503". Test drive vehicle. If DTC P0503 is not present, repair is complete. If DTC P0503 is still present, repeat test.

Check for Electromagnetic Interferences (EMI) induced on VSS circuits caused by misrouted wires along spark plug wires. Ensure VSS is secured to transaxle case extension. Inspect wiring for poor connections at PCM, VSS and at transaxle 20-pin connector. Check for bent, backed out or broken terminals, or misaligned connectors. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. Check for moisture or corrosion. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P0711: TRANS. FLUID TEMPERATURE (TFT) SENSOR CIRCUIT (RANGE/PERFORMANCE)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Transaxle Fluid Temperature (TFT) sensor is a negative coefficient thermistor whose resistance value changes based on temperature. TFT sensor resistance decreases as transaxle fluid warms. PCM provides a 5 volt reference to sensor on TFT signal circuit. A short to ground in circuit results in low signal voltage. TFT operating range is from -40° to 305°F (-40° to 151°C). DTC P0711 is set if PCM detects an intermittent voltage or no voltage change in TFT sensor circuit.

Conditions For Setting DTC P0711

DTC will set under the following conditions

1. DTC P0116, P0117, P0118, P1114 or P1115 (engine coolant temperature) is not present.
2. DTC P0502 or P0503 (vehicle speed sensor) is not present.
3. DTC P0716 or P0717 (input speed sensor) is not present.
4. System voltage is 10-17 volts.
5. Transaxle fluid temperature is -35 to 300°F (-37 to 149°C).
6. Transaxle fluid temperature is -40 to 70°F (-40 to 21°C) at start-up.
7. Engine is running for more than 15 minutes.
8. Vehicle speed is more than 15 MPH for 2 minutes and 30 seconds.
9. TCC slip is more than 4 RPM for one second.
10. Engine coolant temperature is more than 158°F (70°C) and has changed more than 90°F (50°C) since start-up.

Failure Criteria (Case No. 1)

Change in transaxle fluid temperature since start-up is less than 2°F (1.5°C) for 4 minutes and 14 seconds.

Failure Criteria (Case No. 2)

Change in transaxle fluid temperature is more than 36°F (20°C) within 200 milliseconds, 14 times within 7 seconds.

PCM performs the following if DTC is set

1. Will light MIL when fault is set.
2. DTC P0711 is stored in PCM history.

Default Temperatures

PCM will substitute a default transaxle fluid temperature under the following conditions

1. If any ECT DTC is set, PCM substitutes a transaxle fluid temperature default value of 269°F (132°C).
2. If ECT is more than 239°F (115 °C), PCM substitutes a transaxle fluid temperature default value of 269°F (132°C). This enables transaxle hot mode. Transaxle remains in hot mode until ECT drops below 230°F (110°C).
3. If engine run time is less than 3 minutes, PCM substitutes a IAT value for transaxle fluid temperature value at ignition on.
4. If ECT is 113-239°F (45-115°C), transaxle fluid default temperature equals ECT minus 10°F (-10°C) when intake air temperature is less than 81°F (27°C) at ignition on. If intake air temperature is more than 81°F (27°C) at ignition on, transaxle fluid default temperature equals ECT plus 10°F (10°C).
5. If engine run time is more than 3 minutes and ECT is less than 113°F (45°C), PCM substitutes a transaxle fluid temperature default value of 54°F (12°C).

1. Ensure transaxle fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select "TFT" on scan tool. Drive vehicle and observe scan tool for either of the following fail conditions: TFT does not change more than 2°F (1.5°C) in 4 minutes and 14 seconds since start-up, or TFT changes more than 36°F (20°C) in.200 seconds, 14 times within 7 seconds (unrealistic change). If either of these conditions occurred, go to next step. If neither of these conditions occurred, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e).
3. If scan tool displays a condition in which TFT does not change by more than 2°F (1.5°C) in 4 minutes and 14 seconds since start-up, go to step 5. If scan tool does not display a condition in which TFT does not change by more than 2°F (1.5°C) in 4 minutes and 14 seconds since start-up, go to next step.
4. Turn ignition off. Disconnect transaxle 20-pin connector. Install Jumper Harness (J-39775) on engine side of transaxle 20-pin connector. Connect test light between terminals "L" and "M". (Scheme 96) Turn ignition switch to ON position. DO NOT start engine. While observing scan tool, wiggle engine wiring harness from PCM connector C1 to transaxle 20-pin connector. If TFT temperature changes by more than 36°F (20°C), go to step 6. If TFT temperature does not change by more than 36°F (20°C), go to step 7.
5. Turn ignition off. Disconnect transaxle 20-pin connector. Turn ignition switch to ON position. DO NOT start engine. If scan tool displays a condition in which TFT does not change by more than 2°F (1.5°C) in 4 minutes and 14 seconds since start-up, replace PCM, then go to step 8. If scan tool does not display a condition in which TFT does not change by more than 2°F (1.5°C) in 4 minutes and 14 seconds since start-up, replace TFT sensor, then go to step 8.
6. Check for intermittent open or short condition in TFT sensor circuits between PCM connector and transaxle 20-pin connector. Repair circuit(s) as necessary, then go to step 8. If circuits are okay, replace PCM, then go to step 8.
7. Check for intermittent open or short condition in TFT sensor circuits between transaxle 20-pin connector and TFT sensor. Repair circuit(s) as necessary, then go to next step. If circuits are okay, replace TFT sensor, then go to next step.
8. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Select SPECIFIC DTC and enter DTC "P0711". Road test vehicle. Monitor transaxle fluid temperature. Ensure that rise in fluid temperature is more than 5.4°F (3.0°C) within 4 minutes and 14 seconds. If DTC P0711 is not present, repair is complete. If DTC P0711 is still present, repeat test.

Inspect wiring for poor connections at PCM, TFT sensor and at transaxle 20-pin connector. Check for bent, backed out or broken terminals, or misaligned connectors. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. Check for moisture and corrosion. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change. Check transaxle 20-pin connector for transaxle fluid.

DTC P0712: TRANS. FLUID TEMPERATURE (TFT) SENSOR CIRCUIT (LOW INPUT)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Transaxle Fluid Temperature (TFT) sensor is a negative coefficient thermistor whose resistance value changes based on temperature. PCM provides a 5 volt reference to sensor on TFT signal circuit. A high fluid temperature or short to ground in circuit results in low signal voltage. TFT operating range is from -40° to 305°F (-40° to 151°C). DTC P0712 is set if PCM detects a continuous short to ground on TFT sensor circuit.

Conditions For Setting DTC P0712

DTC will set under the following conditions

1. Ignition switch is in ON position.
2. PCM detects a reading of 298°F (148°C) or more for 5 seconds.

PCM performs the following if DTC is set

1. Will not light MIL when fault is set.
2. DTC P0712 is stored in PCM history.

PCM will substitute a default transaxle fluid temperature under the following conditions

1. If any ECT DTC is set, PCM substitutes a transaxle fluid temperature default value of 269°F (132°C).
2. If ECT is more than 239°F (115 °C), PCM substitutes a transaxle fluid temperature default value of 269°F (132°C). This enables transaxle hot mode. Transaxle remains in hot mode until ECT drops below 230°F (110°C).
3. If engine run time is less than 3 minutes, PCM substitutes a IAT value for transaxle fluid temperature value at ignition on.
4. If ECT is 113-239°F (45-115°C), transaxle fluid default temperature equals ECT minus 10°F (-10°C) when intake air temperature is less than 81°F (27°C) at ignition on. If on, transaxle fluid default temperature equals ECT plus 10°F(10°C).
5. If engine run time is more than 3 minutes and ECT is less than 113°F (45°C), PCM substitutes a transaxle fluid temperature default value of 54°F (12°C).

1. Ensure transaxle fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select TFT SENSOR VOLTS on scan tool. If TFT voltage is less than or equal to.08 volt, go to next step. If TFT voltage is more than.08 volt, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e).
3. Turn ignition off. Disconnect transaxle 20-pin connector. Turn ignition switch to ON position. DO NOT start engine. If TFT voltage is less than 4.8 volts, go to step 7. If TFT voltage is more than 4.8 volts, go to next step.
4. Install Jumper Harness (J-39775) on transaxle side of 20-pin connector. Measure resistance between transaxle 20-pin connector terminals "L" and "M". If resistance is 3088-3942 ohms at 68°F (20°C) or 159-198 ohms at 176°F (80°C), go to next step. If resistance is not as specified, go to step 6.
5. Using a DVOM, measure resistance between transaxle 20-pin connector terminal "M" and ground. (Scheme 96) If resistance is more than 100 ohms, replace PCM, then go to step 9. If resistance is less than 100 ohms, go to step 8.
6. Disconnect TFT sensor connector. Measure resistance between transaxle 20-pin connector terminals "L" and "M". If resistance is 100 ohms or more, replace TFT sensor, then go to step 9. If resistance is less than 100 ohms, repair or replace transaxle harness, then go to step 9.
7. Check for short to ground in TFT sensor high circuit between PCM and transaxle 20-pin connector. Repair wire as necessary, then go to step 9. If circuit is okay, replace PCM, then go to step 9.
8. Check for short to ground in TFT sensor high circuit between PCM and TFT sensor. Repair circuit as necessary, then go to next step. If circuit is okay, replace TFT sensor, then go to next step.
9. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Start engine and select TFT SENSOR VOLTS on scan tool. With engine idling, monitor TFT sensor voltage. Ensure TFT voltage is more than.08 volt for 5 seconds. Select SPECIFIC DTC and enter DTC "P0712". If DTC P0712 is not present, repair is complete. If DTC P0712 is still present, repeat test.

Inspect wiring for poor connections at PCM, TFT sensor and at transaxle 20-pin connector. Check for bent, backed out or broken terminals, or misaligned connectors. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. Check for moisture and corrosion. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P0713: TRANS. FLUID TEMPERATURE (TFT) SENSOR CIRCUIT (HIGH INPUT)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Transaxle Fluid Temperature (TFT) sensor is a negative coefficient thermistor whose resistance value changes based on temperature. PCM provides a 5 volt reference to sensor on TFT signal circuit. An open in circuits or low fluid temperature result in high signal voltage. TFT operating range is from -40° to 305°F (-40° to 151°C). DTC P0713 is set if PCM detects a continuous open or short to power on TFT sensor circuit.

Conditions For Setting DTC P0713

DTC will set under the following conditions

1. Engine run time is more than 5 minutes.
2. PCM detects a reading of -40°F (-40°C) or less (5.04 volts or more) for 6 seconds.
3. Vehicle speed is more than 10 MPH for 5 minutes.
4. ECT is more than -13°F (-25°C).

PCM performs the following if DTC is set

1. Will not light MIL when fault is set.
2. DTC P0713 is stored in PCM history.

PCM will substitute a default transaxle fluid temperature under the following conditions

1. If any ECT DTC is set, PCM substitutes a transaxle fluid temperature default value of 269°F (132°C).
2. If ECT is more than 239°F (115 °C), PCM substitutes a transaxle fluid temperature default value of 269°F (132°C). This enables transaxle hot mode. Transaxle remains in hot mode until ECT drops below 230°F (110°C).
3. If engine run time is less than 3 minutes, PCM substitutes a IAT value for transaxle fluid temperature value at ignition on.
4. If ECT is 113-239°F (45-115°C), transaxle fluid default temperature equals ECT minus 10°F (-10°C) when intake air temperature is less than 81°F (27°C) at ignition on. If intake air temperature is more than 81°F (27°C) at ignition on, transaxle fluid default temperature equals ECT plus 10°F (10°C).
5. If engine run time is more than 3 minutes and ECT is less than 113°F (45°C), PCM substitutes a transaxle fluid temperature default value of 54°F (12°C).

1. Ensure transaxle fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select TFT SENSOR VOLTS on scan tool. If TFT voltage is more than or equal to 4.98 volts, go to next step. If TFT voltage is less than 4.98 volts, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e).
3. Turn ignition off. Disconnect transaxle 20-pin connector. Connect fused jumper wire between transaxle 20-pin connector terminal "M" (PCM side of harness) and transaxle case. (Scheme 96) Turn ignition switch to ON position. DO NOT start engine. If TFT voltage is more than or equal to 4.98 volts, go to next step. If TFT voltage is less than 4.98 volts, go to step 6.
4. Check for open in TFT sensor high circuit between PCM and transaxle 20-pin connector. Repair wire as necessary, then go to step 7. If circuit is okay, go to next step.
5. Check for open in TFT sensor low circuit between PCM and transaxle 20-pin connector. Repair wire as necessary, then go to step 7. If circuit is okay, replace PCM, then go to next step.
6. Check for open in TFT sensor high and low circuits between transaxle 20-pin connector (transaxle side of harness) and TFT sensor. Repair wire(s) as necessary, then go to next step. If circuits are okay, replace TFT sensor, then go to next step.
7. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Road test vehicle. Ensure vehicle speed is more than 10 MPH for 5 minutes. Select SPECIFIC DTC and enter DTC "P0713". Start engine and run for 15 seconds. If DTC P0713 is not present, repair is complete. If DTC P0713 is still present, repeat test.

Inspect wiring for poor connections at PCM, TFT sensor and at transaxle 20-pin connector. Check for bent, backed out or broken terminals, or misaligned connectors. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. Check for moisture and corrosion. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P0716: INPUT SPEED SENSOR CIRCUIT (RANGE/PERFORMANCE OR INTERMITTENT)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Transaxle input speed sensor consists of a permanent magnet surrounded by a coil of wire. Rotation of input shaft drive sprocket housing induces an AC voltage in circuit. Signal voltage and frequency vary directly with input shaft drive sprocket rotational speed. An air gap of .045-.109" (1.14-2.77 mm) must be maintained between sensor and drive sprocket in order to transmit an accurate AC voltage. This DTC indicates stuck, erratic or intermittent values, indicating poor system performance. Input speed sensor has a resistance of 1260-1540 ohms. Sensor voltage varies from .5 volt AC at 100 RPM to more than 100 volts at 8000 RPM. P0716 is set if PCM detects an unrealistically large change in input speed.

Conditions For Setting DTC P0716

DTC will set under the following conditions

1. DTCs P0121, P0122 or P0123 (throttle position sensor) are not present.
2. DTCs P0502 or P0503 (vehicle speed sensor) are not present.
3. DTC P0717 (input speed sensor signal) is not present.
4. DTCs P0751 or P0753 (1-2 shift solenoid) are not present.
5. DTCs P0756 or P0758 (2-3 shift solenoid) are not present.
6. Vehicle speed is more than 7 MPH.
7. Throttle angle is more than 12.8 degrees.
8. Engine is running for 5 seconds and not in fuel cutoff.
9. Input speed varies by 1000 RPM for more than .075 seconds, occurring 10 times in 10 seconds.

PCM performs the following if DTC is set

1. Will light MIL when fault is set.
2. SERVICE ENGINE SOON, SERVICE TRANSMISSION will be displayed on Drivers Information Center (DIC).
3. Freezes shift adapts from being updated.
4. Defaults to line pressure.
5. Inhibits TCC engagement.
6. Calculates input speed from vehicle speed and command gear.
7. DTC P0716 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select TRANS ISS on scan tool. Start engine. If ISS RPM is less than or equal to 500 RPM, go to next step. If ISS RPM is more than 500 RPM, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e).
3. Turn ignition off. Install Jumper Harness (J-39775) on transaxle side of 20-pin connector. Using a DVOM, measure resistance between terminal "S" and terminal "V". If resistance is 1260-1540 ohms, go to step 6. If resistance is less than 1260 ohms, go to step 5. If resistance is more than 1540 ohms, go to next step.
4. Check for open in ISS sensor high and low circuits between transaxle 20-pin connector (transaxle side of harness) and ISS sensor. Repair or replace transaxle wiring harness as necessary, then go to step 12. If circuits are okay, replace ISS sensor, then go to step 12.
5. Check for short between ISS sensor high and low circuits between transaxle 20-pin connector (transaxle side of harness) and ISS sensor. Check for wires shorted together. Repair or replace transaxle wiring harness as necessary, then go to step 12. If circuits are okay, replace ISS sensor, then go to step 12.
6. Turn ignition off. Disconnect PCM connector C1. Using DVOM, measure voltage between ISS sensor high and low circuit at PCM connector C1 terminals No. 5 and 6 while cranking engine. (Scheme 97) See «WIRING DIAGRAMS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e). If voltage is more than.5 volt, replace PCM, then go to step 12. If voltage is less than.5 volt, go to next step.
7. Turn ignition off. Reconnect PCM connector C1. Disconnect transaxle 20-pin connector. Connect DVOM between transaxle 20-pin connector terminal "S" (PCM side of harness) and ground. (Scheme 96) Turn ignition on. If voltage is less than 300 mV, go to next step. If voltage is more than 300 mV, go to step 9.
8. Check ISS sensor high circuit for open or short to ground between PCM and transaxle 20-pin connector. Repair wire as necessary, then go to step 12. If circuit is okay, replace PCM, then go to step 12.
9. Connect test light between transaxle 20-pin connector terminal "E" and terminal "V". If test light does not glow, go to step 3. If test light glows, go to next step.
10. Check ISS sensor low circuit for open between PCM and transaxle 20-pin connector. Repair wire as necessary, then go to step 12. If circuit is okay, replace PCM, then go to step 12.
11. Using a DVOM, measure resistance between transaxle 20-pin connector terminal "A" (transaxle side of harness) and ground. If resistance is 100 ohms or more, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e), then go to next step. If resistance is less than 100 ohms, replace transaxle wiring harness, then go to next step.
12. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Road test vehicle with throttle angle more than 13 degrees and at speed more than 7 MPH. Select SPECIFIC DTC and enter DTC "P0716". If DTC P0716 is not present, repair is complete. If DTC P0716 is still present, repeat test.

Inspect wiring for poor connections at PCM, ISS and at transaxle 20-pin connector. Ensure engine wiring harness is not located near spark plug wires or DIS coils. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. Check for moisture or corrosion. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P0717: INPUT SPEED SENSOR CIRCUIT (NO SIGNAL OR LOW INPUT)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Transaxle input speed sensor consists of a permanent magnet surrounded by a coil of wire. Rotation of input shaft drive sprocket housing induces an AC voltage in circuit. Signal voltage and frequency vary directly with input shaft drive sprocket rotational speed. An air gap of .045-.109" (1.14-2.77 mm) must be maintained between sensor and drive sprocket in order to transmit an accurate AC voltage. Input speed sensor has a resistance of 1260-1540 ohms. Sensor voltage varies from .5 volt AC at 100 RPM to more than 100 volts at 8000 RPM. P0717 is set if PCM detects a low input speed while vehicle and engine speed is high.

Conditions For Setting DTC P0717

DTC will set under the following conditions

1. DTCs P0121, P0122 or P0123 (throttle position sensor) are not present.
2. DTCs P0502 or P0503 (vehicle speed sensor) are not present.
3. DTC P1810 (TFP valve position switch) is not present.
4. Vehicle speed is more than 10 MPH.
5. Engine is running for 5 seconds
6. Engine is not in fuel cut off mode.
7. Transaxle is not in Park or Neutral.
8. Measured input speed is less than 50 RPM for at least 2 seconds.

PCM performs the following if DTC is set

1. Will light MIL when fault is set.
2. SERVICE ENGINE SOON, SERVICE TRANSMISSION will be displayed on Drivers Information Center (DIC).
3. Freezes shift adapts from being updated.
4. Defaults to line pressure.
5. Inhibits TCC engagement.
6. Calculates input speed from vehicle speed and command gear.
7. DTC P0717 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select TRANS ISS on scan tool. Start engine. If ISS RPM is less than or equal to 500 RPM, go to next step. If ISS RPM is more than 500 RPM, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e).
3. Turn ignition off. Disconnect PCM connector C1. Using DVOM, measure voltage between ISS sensor high and low circuit terminals at PCM connector C1 while cranking engine. (Scheme 97) See «WIRING DIAGRAMS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e). If voltage is more than.5 volt, replace PCM, then go to step 12. If voltage is.5 volt or less, go to next step.
4. Turn ignition off. Reconnect PCM connector C1. Disconnect transaxle 20-pin connector. Connect DVOM between transaxle 20-pin connector terminal "S" (PCM side of harness) and ground. (Scheme 96) Turn ignition on. If voltage is less than 300 mV, go to next step. If voltage is more than 300 mV, go to step 6.
5. Check ISS sensor high circuit for open or short to ground between PCM and transaxle 20-pin connector. Repair wire as necessary, then go to step 12. If circuit is okay, replace PCM, then go to step 12.
6. Connect test light between transaxle 20-pin connector terminal "E" and terminal "V". If test light does not glow, go to step 8. If test light glows, go to next step.
7. Check ISS sensor low circuit for open between PCM and transaxle 20-pin connector. Repair wire as necessary, then go to step 12. If circuit is okay, replace PCM, then go to step 12.
8. Turn ignition off. Install Jumper Harness (J-39775) on transaxle side of 20-pin connector. Using a DVOM, measure resistance between terminal "S" and terminal "V". If resistance is 1260-1540 ohms, go to step 11. If resistance is less than 1260 ohms, go to step 10. If resistance is more than 1540 ohms, go to next step.
9. Check for open in ISS sensor high and low circuits between transaxle 20-pin connector (transaxle side of harness) and ISS sensor. Repair wire(s) as necessary, then go to step 12. If circuits are okay, replace ISS sensor, then go to step 12.
10. Check for short between ISS sensor high and low circuits between transaxle 20-pin connector (transaxle side of harness) and ISS sensor. Check for wires shorted together. Repair wire(s) as necessary, then go to step 12. If circuits are okay, replace ISS sensor, then go to step 12.
11. Using a DVOM, measure resistance between ISS sensor connector terminal "A" and ground. If resistance is 100 ohms or more, problem is intermittent. See «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e), then go to next step. If resistance is less than 100 ohms, replace transaxle wiring harness, then go to next step.
12. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Start engine. Ensure ISS is more than 50 RPM for 2 seconds. Select SPECIFIC DTC and enter DTC "P0717". If DTC P0717 is not present, repair is complete. If DTC P0717 is still present, repeat test.

Inspect wiring for poor connections at PCM, ISS and at transaxle 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change. Check transaxle 20-pin connector for transaxle fluid contamination.

DTC P0719: TCC BRAKE SWITCH CIRCUIT LOW INPUT (SWITCH STUCK ON)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Torque Converter Clutch (TCC) brake switch is used to indicate brake pedal status to PCM. DTC P0719 is set if PCM detects a status change in brakelight switch and extended travel brake switch input without status change of TCC brake switch input.

Conditions For Setting DTC P0719

DTC will set under the following conditions

1. DTCs P0502 or P0503 (vehicle speed sensor) are not present.
2. DTCs P1574 and P1575 (extended travel and brakelight switch) are not present.
3. DTC P1602 (loss of PCM serial data) is not present.
4. TCC brake switch input is zero volt.
5. Traction control and ABS are not active.
6. Vehicle speed and wheel sensor speed are within 6 MPH.

The following conditions must occur 7 times within 15 minutes without status change of TCC brake input

1. Vehicle speed is less than 5 MPH.
2. Vehicle takes more than 2.5 seconds to accelerate to 20 MPH, then vehicle speed remains above 20 MPH for at least 6 seconds.

PCM performs the following if DTC is set

1. Will not light MIL when fault is set.
2. For TCC operation, PCM will use extended travel brake switch or brakelight switch input.
3. SERVICE ELECTRICAL SYSTEM will be displayed on Drivers Information Center (DIC).
4. DTC P0719 is stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. If DTCs P1574 or P1575 are also present, remove and inspect SHIFT SOL fuse. See «WIRING DIAGRAMS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) . If fuse is open, check for short to ground in brake switch circuits to fuse. Repair circuit as necessary, then go to step 4 . Replace fuse. If DTCs are not present, go to next step.
3. Select TCC BRAKE SWITCH on scan tool. Disconnect TCC brake switch. Connect fused jumper wire between brake switch connector terminals. If brake switch status on scan tool changes from open to closed, replace TCC brake switch, then go to next step. If brake switch status on scan tool does not change, check for open in brake switch input circuit. Repair circuit as necessary, then go to next step. If circuit is okay, replace PCM, then go to next step.
4. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Select SPECIFIC DTC and enter DTC "P0719". Operate vehicle and ensure PCM senses ignition voltage on TCC brake switch input circuit for more than 2 seconds. If DTC P0719 is not present, repair is complete. If DTC P0719 is still present, repeat test.

Check TCC brake switch for proper adjustment. Inspect wiring for poor connections at PCM and at transaxle 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. Check for moisture or corrosion. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P0724: TCC BRAKE SWITCH CIRCUIT HIGH INPUT (SWITCH STUCK OFF)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Torque Converter Clutch (TCC) brake switch is used to indicate brake pedal status to PCM. DTC P0724 is set if PCM detects an status change in brakelight switch and extended travel brake switch input without status change of TCC brake switch input.

Conditions For Setting DTC P0724

DTC will set under the following conditions

1. DTCs P0502 or P0503 (vehicle speed sensor) are not present.
2. DTCs P1574 and P1575 (extended travel and brakelight switch) are not present.
3. DTC P1602 (loss of PCM serial data) is not present.
4. TCC brake switch input is ignition voltage.
5. Traction control and ABS are not active.
6. Vehicle speed and wheel sensor speed are within 6 MPH.

The following conditions must occur 7 times without status change of TCC brake input

1. Vehicle speed is more than 20 MPH for more than 6 seconds, then vehicle takes more than 12 seconds to decrease speed to 5 MPH.

PCM performs the following if DTC is set

1. Will not light MIL when fault is set.
2. For TCC operation, PCM will use extended travel brake switch or brakelight switch input.
3. SERVICE ELECTRICAL SYSTEM will be displayed on Drivers Information Center (DIC).
4. PCM disables shift adapts.
5. DTC P0724 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select TCC BRAKE SWITCH on scan tool. Disconnect TCC brake switch connector. If brake switch status on scan tool changed from closed to open, replace TCC brake switch, then go to next step. If brake switch status on scan tool does not change, check for short to voltage in brake switch input circuit. Repair circuit as necessary, then go to next step. If circuit is okay, replace PCM, then go to next step.
3. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Turn ignition switch to ON position. Apply brakes for 2 seconds. Select SPECIFIC DTC and enter DTC "P0724". If DTC P0724 is not present, repair is complete. If DTC P0724 is still present, repeat test.

Check TCC brake switch for proper adjustment. Inspect wiring for poor connections at PCM and at transaxle 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. Check for moisture or corrosion. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P0730: INCORRECT GEAR RATIO

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS . For fluid circuit identification, see OIL CIRCUIT DIAGRAMS in section No. 1.

PCM calculates gear ratio based on data from input and output speed sensors. PCM compares known gear ratio to calculated ratio for each gear selected. DTC P0730 is set if PCM detects steady state adapts at maximum and incorrect gear ratio due to excessive transaxle slip.

Conditions For Setting DTC P0730

DTC will set under the following conditions

1. DTCs P0101, P0102 and P0103 (MAF sensor), or P0121, P0122 and P0123 (throttle position sensor) are not present.
2. DTC P0502 or P0503 (vehicle speed sensor) is not present.
3. DTCs P0716 and P0717 (input speed sensor) and P1810 (TFP valve position switch) are not present.
4. Transaxle is not in Park or Neutral.
5. DTC P0753 (1-2 shift solenoid) is not present.
6. DTC P0758 (2-3 shift solenoid) is not present.
7. Vehicle speed is more than 7 MPH.
8. Engine is not in fuel cut off mode.
9. Throttle angle is more than 15.7 degrees.
10. Engine is running for 5 seconds.
11. One or more steady state cell at maximum.
12. TFT is more than 68°F (20°C).
13. Torque is more than 100 ft. lbs. (135 N.m).

The following conditions must occur for 4 seconds

1. 1st gear ratio is less than 2.87 or more than 3.11.
2. 2nd gear ratio is less than 1.54 or more than 1.71.
3. 3rd gear ratio is less than .95 or more than 1.05.
4. 4th gear ratio is less than .65 or more than .71.
5. Reverse gear ratio is less than 2.02 or more than 2.23.

PCM performs the following if DTC is set

1. Will not light MIL when fault is set.
2. SERVICE ENGINE SOON, SERVICE TRANSMISSION will be displayed on Drivers Information Center (DIC).
3. Commands maximum line pressure.
4. Disables all adapts.
5. DTC P0730 is stored in PCM history.

1. Ensure fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test. If DTCs P0502, P0503, P0716, P0717, P0753 or P0758 are set, repair these DTCs first, then go to step 22 . If DTCs P0502, P0503, P0716, P0717, P0753 or P0758 are not set, go to next step.
2. Connect oil pressure gauge to line pressure test port. See HYDRAULIC PRESSURE TESTS in HYDRA-MATIC 4T80-E OVERHAUL article . Select OUTPUT CONTROL PC SOL on scan tool. Start engine and allow to idle in Park position. Increase and decrease PC solenoid valve amperage. If line pressure and amperage are 50-220 psi/.1-1.1 amps, go to next step. If line pressure and amperage are more than 50-220 psi/.1-1.1 amps, inspect and repair PC solenoid valve. See «CIRCUIT TESTS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) . If line pressure and amperage are less than 50-220 psi/.1-1.1 amps, inspect and repair following: Scavenge pump leaking at pump body. Scavenge tube restriction. Scavenge tube seals damaged or leaking. Primary pump leaking at gasket or pump body. Clogged screens. Pressure relief valve stuck. Secondary pump leaking at gasket or pump body. See COMPONENT DISASSEMBLY & REASSEMBLY in HYDRA-MATIC 4T80-E OVERHAUL article, then go to step 22 . NOTE: All TFP valve position switch range status will be given in A/B/C order (Example: ON/OFF/ON).
3. Select snap shot mode on scan tool and capture TFP VAL POSITION SW, transaxle gear ratio and current gear. Drive vehicle in reverse. If TFP valve position switch parameters are On/On/Off with a gear ratio of more than 2.22 or less than 2.02, repair valve body hydraulic problem, then go to step 22 . See HYDRA-MATIC 4T80-E OVERHAUL article. If TFP valve position switch parameters are not On/On/Off with a gear ratio of more than 2.22 or less than 2.02, go to next step.
4. Drive vehicle in OD and ensure vehicle reaches 4th gear. If TFP valve position switch parameters are Off/On/On with a gear ratio of less than .65, inspect and repair VSS and ISS circuits. See DTCs P0502, P0503, P0716 and P0717, then go to step 22 . If TFP valve position switch parameters are not Off/On/On with a gear ratio of less than .65, go to next step.
5. If TFP valve position switch parameters are Off/On/On with a gear ratio of more than 1.05, inspect and repair 3rd clutch, forward clutch and forward clutch sprag, then go to step 22 . If TFP valve position switch parameters are not Off/On/On with a gear ratio of more than 1.05, go to next step.
6. If TFP valve position switch parameters are On/Off/Off with a gear ratio of more than 1.71, inspect and repair 2nd clutch, 2nd sprag clutch, forward clutch and forward sprag clutch, then go to step 22 . If TFP valve position switch parameters are not On/Off/Off with a gear ratio of more than 1.71, go to next step.
7. If TFP valve position switch parameters are On/Off/Off with a gear ratio of less than 1.54, inspect and repair 3rd clutch, forward clutch and forward sprag clutch, then go to step 22 . If TFP valve position switch parameters are not On/Off/Off with a gear ratio of more than 1.71, go to next step.
8. If TFP valve position switch parameters are On/Off/Off with a gear ratio of less than 2.87, inspect and repair 2nd clutch, 2nd sprag clutch, forward clutch and forward sprag clutch, then go to step 22 . If TFP valve position switch parameters are not On/Off/Off with a gear ratio of less than 2.87, go to next step.
9. Drive vehicle in 3rd gear. If TFP valve position switch parameters are On/On/Off with a gear ratio of less than .95, inspect and repair valve body hydraulic problem or a clutch not releasing, then go to step 22 . If TFP valve position switch parameters are not On/On/Off with a gear ratio of less, than .95, go to next step.
10. If TFP valve position switch parameters are On/On/Off with a gear ratio of less than .95 and more than .71, inspect and repair 4th band, 3rd clutch, 4th clutch and forward sprag clutch, then go to step 22 . If TFP valve position switch parameters are not On/On/Off with a gear ratio of less than .95 and more than .71, go to next step.
11. If TFP valve position switch parameters are On/On/Off with a gear ratio of more than 1.05, inspect and repair 3rd clutch, forward clutch and forward sprag clutch, then go to step 22 . If TFP valve position switch parameters are not On/On/Off with a gear ratio of more than 1.05, go to next step.
12. If TFP valve position switch parameters are On/On/Off with a gear ratio of more than 1.71 inspect and repair 2nd clutch, forward clutch and forward sprag clutch, then go to step 22 . If TFP valve position switch parameters are not On/On/Off with a gear ratio of more than 1.71, go to next step.
13. If TFP valve position switch parameters are On/On/Off with a gear ratio of less than 1.54, inspect and repair 3rd clutch, forward clutch and forward sprag clutch, then go to step 22 . If TFP valve position switch parameters are not On/On/Off with a gear ratio of less than 1.54, go to next step.
14. If TFP valve position switch parameters are On/On/Off with a gear ratio of less than 2.87, inspect and repair 2nd clutch, 2nd sprag clutch, forward clutch and forward sprag clutch, then go to step 22 . If TFP valve position switch parameters are not On/On/Off with a gear ratio of less than 2.87, go to next step.
15. Drive vehicle in 2nd gear. If TFP valve position switch parameters are On/On/On with a gear ratio of less than 1.54, inspect and repair valve body hydraulic problem or a clutch not releasing, then go to step 22 . If TFP valve position switch parameters are not On/On/On with a gear ratio of less than 1.54, go to next step.
16. If TFP valve position switch parameters are On/On/On with a gear ratio of more than 1.05, inspect and repair 3rd clutch, forward clutch and forward sprag clutch, then go to step 22 . If TFP valve position switch parameters are not On/On/On with a gear ratio of more than 1.05, go to next step.
17. If TFP valve position switch parameters are On/On/On with a gear ratio of more than 1.71, inspect and repair 2nd clutch, 2nd sprag clutch, forward clutch and forward sprag clutch, then go to step 22 . If TFP valve position switch parameters are not On/On/Off with a gear ratio of more than 1.71, go to next step.
18. If TFP valve position switch parameters are On/On/On with a gear ratio of less than 1.54, inspect and repair 3rd clutch, forward clutch and forward sprag clutch, then go to step 22 . If TFP valve position switch parameters are not On/On/On with a gear ratio of less than 1.54, go to next step.
19. If TFP valve position switch parameters are On/On/On with a gear ratio of less than 2.87, inspect and repair 2nd clutch, 2nd sprag clutch, forward clutch and forward sprag clutch, then go to step 22 . If TFP valve position switch parameters are not On/On/On with a gear ratio of less than 2.87, go to next step.
20. Drive vehicle in 1st gear. If TFP valve position switch parameters are Off/On/On with a gear ratio of less than 2.87, inspect and repair valve body hydraulic problem or a clutch not releasing, then go to step 22 . If TFP valve position switch parameters are not Off/On/On with a gear ratio of less than 2.87, go to next step.
21. If TFP valve position switch parameters are Off/On/On with a gear ratio of more than 3.11, inspect and repair forward clutch, forward sprag clutch and lo roller clutch, then go to next step. If TFP valve position switch parameters are not Off/On/On with a gear ratio of more than 3.11, replace PCM, then go to next step.
22. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Road test vehicle in all gears. With vehicle in "OD", accelerate with throttle angle more than 16 degrees. Engine torque must be more than 100 ft. lbs. (135 N.m). Select SPECIFIC DTC and enter DTC "P0730". If DTC P0730 is not present, repair is complete. If DTC P0730 is still present, repeat test.

Ensure vehicle final drive ratio matches PROM calibration.

DTC P0741: TCC CIRCUIT INOPERATIVE (STUCK OFF)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS . For fluid circuit identification, see OIL CIRCUIT DIAGRAMS in section No. 1.

Torque Converter Clutch (TCC) Pulse Width Modulated (PWM) solenoid controls fluid for TCC apply and release. PCM commands solenoid on and off through ground circuit. When TCC PWM solenoid is de-energized, solenoid will release fluid and release TCC. DTC P0741 is set if PCM detects a high torque converter slip when TCC is commanded on.

Conditions For Setting DTC P0741

DTC will set under the following conditions

1. DTC P0101, P0102 or P0103 (MAF sensor) is not present.
2. DTC P0121, P0122 or P0123 (throttle position sensor) is not present.
3. DTC P0502 or P0503 (vehicle speed sensor) is not present.
4. DTC P0716 or P0717 (input speed sensor) is not present.
5. DTC P0742 (TCC stuck on) is not present.
6. DTC P1810 (TFP valve position switch) is not present.
7. DTC P1860 (TCC PWM solenoid) is not present.
8. Throttle angle is more than 8 degrees.
9. Engine must be running for at least 5 seconds.
10. Gear ratio must indicate 2nd, 3rd or 4th gear.
11. TFP valve position switch indicates D4.
12. Fluid temperature must be 0-266°F (-18-130°C).
13. TCC slip speed does not exceed torque limits.
14. Delivered torque is 32-150 ft. lbs. (43-202 N.m).
15. Engine is not in fuel shut off mode.
16. TCC solenoid valve is commanded on at maximum duty cycle.

PCM performs the following if DTC is set

1. Will light MIL at first failure signal.
2. SERVICE ENGINE SOON, SERVICE TRANSMISSION will be displayed on Drivers Information Center (DIC).
3. Inhibits TCC engagement and 4th gear.
4. DTC P0741 will be stored in PCM history.

1. Ensure transaxle fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. If DTC P0719 is present, repair this DTC first, then go to next step. If DTC P0719 is not present, go to next step.
2. Drive vehicle at 45 MPH. Select OUTPUT TEST. Select TCC ENA SOL. Command TCC solenoid on. Monitor TCC slip speed. If TCC slip speed is -5 to 80 RPM, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) . If TCC slip speed is not -5 to 80 RPM, check and repair the following, then go to next step. See HYDRA-MATIC 4T80-E OVERHAUL article. TCC control valve, regulator valve or feed valve are stuck off. Oil pressure screen plugged. TCC solenoid "O" ring is leaking or cut. Turbine shaft seals are cut or worn. Torque converter for ballooning.
3. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Drive vehicle in "D4". Ensure TCC applies for more than 5 seconds. Select SPECIFIC DTC and enter DTC "P0741". If DTC P0741 is not present, repair is complete. If DTC P0741 is still present, repeat test.

Ensure transaxle fluid level is correct. Transaxle may be in hot mode. Inspect transaxle cooler lines to radiator. Lines may be pinched, plugged or twisted.

DTC P0742: TCC CIRCUIT INOPERATIVE (STUCK ON)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS . For fluid circuit identification, see OIL CIRCUIT DIAGRAMS in section No. 1.

Torque Converter Clutch (TCC) Pulse Width Modulated (PWM) solenoid controls fluid for TCC apply and release. Under vehicle acceleration, TCC is disengaged. DTC P0742 is set if PCM detects TCC slip from 50 RPM to 135 RPM when TCC is commanded off.

Conditions For Setting DTC P0742

DTC will set under the following conditions

1. DTC P0101, P0102 or P0103 (MAF sensor) is not present.
2. DTC P0121, P0122 or P0123 (throttle position sensor) is not present.
3. DTC P0502 or P0503 (vehicle speed sensor) is not present.
4. DTC P0716 or P0717 (input speed sensor) is not present.
5. DTC P0741 (TCC stuck off) is not present.
6. DTC P1810 (TFP valve position switch) is not present.
7. DTC P1860 (TCC PWM solenoid) is not present.
8. Throttle angle is more than 15.3 degrees.
9. Engine must be running for at least 5 seconds.
10. TCC solenoid valve is commanded off by PCM.
11. TFP valve position switch indicates D4.
12. Transaxle gear ratio indicates 2nd, 3rd or 4th gear.
13. Delivered torque is 118-162 ft. lbs. (160-220 N.m).
14. TCC slip speed is from 50 RPM to 135 RPM for 5 seconds.

PCM performs the following if DTC is set

1. Will light MIL when fault is set.
2. SERVICE ENGINE SOON, SERVICE TRANSMISSION will be displayed on Drivers Information Center (DIC).
3. Inhibits TCC engagement.
4. Inhibits 4th gear if transaxle is in hot mode.
5. DTC P0742 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Drive vehicle in "D4" in 4th gear under steady acceleration with throttle angle more than 25 percent. While TCC duty cycle is zero percent, if scan tool displays a TCC slip speed less than 135 RPM, inspect and repair TCC PWM solenoid valve or TCC feed valve. Components may be stuck on due to sediment. See HYDRA-MATIC 4T80-E OVERHAUL article. If scan tool does not display a TCC slip speed less than 135 RPM, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) .
3. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Road test vehicle. TCC slip must be less than 50 RPM and more than 135 RPM for 4 seconds. Select SPECIFIC DTC and enter DTC "P0742". If DTC P0742 is not present, repair is complete. If DTC P0742 is still present, repeat test.

Inspect transaxle fluid for sediment or debris.

DTC P0748: PRESSURE CONTROL SOLENOID (CIRCUIT ELECTRICAL MALFUNCTION)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Pressure Control Solenoid (PCS) valve regulates actuator feed fluid for torque signal pressure. PCM uses Pulse Width Modulated (PWM) signal to regulate torque signal pressure. PCM varies current to PCS valve from .1 amp for maximum line pressure to -1.1 amps for minimum line pressure. DTC P0748 is set if PCM detects a commanded current draw that differs from actual current draw by more than a calibrated value.

Conditions For Setting DTC P0748

DTC will set under the following conditions

1. System voltage is 10-17 volts.
2. DTC P0730 (incorrect gear ratio) is not present.
3. DTC P1811 (maximum adapt and long shift) is not present.
4. Engine has been running for more than one second.
5. Difference between actual PCS valve current draw and commanded current draw is .05 amp or more for 2 seconds.

PCM performs the following if DTC is set

1. Will not light MIL when fault is set.
2. SERVICE VEHICLE SOON, SERVICE TRANSMISSION will be displayed on Drivers Information Center (DIC).
3. Commands maximum line pressure.
4. Disables shift adapts.
5. DTC P0748 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test. Start engine. Select A/T OUTPUTS PC SOL on scan tool. Apply current from.1-1.1 amps at different settings. If PCS differs from command current by more than.05 amp, go to next step. If PCS does not differ from command current by more than.05 amp, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e).
2. Turn ignition off. Disconnect transaxle 20-pin connector. Install Transaxle Jumper Harness (J-39775) to transaxle side of transaxle 20-pin connector. Connect DVOM between terminal "C" and terminal "D". (Scheme 96) If resistance is 3-8 ohms, go to next step. If resistance is more than 8 ohms, inspect and repair PC solenoid circuits of transaxle harness for an open, then go to step 5. If resistance is less than 3 ohms, inspect and repair PC solenoid circuits of transaxle harness for being shorted together, then go to step 5. If circuits are okay, replace PCS valve.
3. Connect DVOM between terminal "D" and transaxle case. If resistance is less than 10 ohms, inspect and repair PC solenoid circuits of transaxle harness for a short to ground, then go to step 5. If resistance is more than 10 ohms, go to next step. If circuits are okay, replace PCS valve.
4. Disconnect transaxle jumper harness from transaxle 20-pin connector. Reconnect transaxle 20-pin connector. Disconnect PCM connector C1. Connect DVOM between terminal No. 38 of PCM connector C1 (PC sol valve low control circuit) and ground. (Scheme 97) If resistance is more than 10 ohms, inspect and repair PC solenoid circuits of transaxle harness for an open, then go to next step. If resistance is less than 10 ohms, inspect and repair PC solenoid circuits of transaxle harness for a short to ground, then go to next step. If circuits are okay, replace PCM.
5. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Start engine and run for at least 30 seconds. Select SPECIFIC DTC and enter DTC "P0748". If DTC P0748 is not present, repair is complete. If DTC P0748 is still present, repeat test.

Inspect wiring for poor connections at PCM, pressure control solenoid and at transaxle 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. Check for moisture or corrosion. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P0751: 1-2 SHIFT SOLENOID (PERFORMANCE MALFUNCTION)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS . For fluid circuit identification, see OIL CIRCUIT DIAGRAMS in section No. 1.

PCM identifies a 1-2 shift solenoid problem by monitoring commanded gear and speed ratio. DTC P0751 is set if PCM detects a gear ratio outside limits for specific commanded gear.

Conditions For Setting DTC P0751

DTC will set under the following conditions

1. DTC P0101, P0102 or P0103 (MAF sensor) is not present.
2. DTC P0121, P0122 or P0123 (throttle position sensor) is not present.
3. DTC P0502 or P0503 (vehicle speed sensor) is not present.
4. DTC P0716 or P0717 (input speed sensor) is not present.
5. DTC P0753 (1-2 shift solenoid electrical problem) or DTC P0758 (2-3 shift solenoid electrical problem) are not present.
6. DTC P1810 (transaxle fluid pressure switch) is not present.
7. DTC P1860 (TCC PWM solenoid) is not present.
8. Engine has been running for 5 seconds.
9. Vehicle speed is more than 4 MPH.
10. Engine is not in fuel shut off mode.
11. Transaxle temperature is more than 0°F (-18°C).
12. Transaxle shift is not in progress.
13. Throttle angle is more than 11 degrees.
14. Transaxle Fluid Pressure (TFP) valve position switch indicates D1, D2, D3 or D4.

PCM performs the following if DTC is set

1. Will light MIL when fault is set.
2. SERVICE ENGINE SOON, SERVICE TRANSMISSION will be displayed on Drivers Information Center (DIC).
3. Commands 2nd gear.
4. Defaults to line pressure.
5. Disables state and shift adapts.
6. Inhibits TCC engagement.
7. DTC P0751 will be stored in PCM history

DTC has 4 different failure criteria. These criteria are as follows

Criteria No. 1

1st gear is commanded. Gear ratio is 1.54-1.71 for one second. Delivered torque is more than 60 lbs. (82 N.m).

Criteria No. 2

2nd gear is commanded. Gear ratio is 2.87-3.11 for 3 seconds. Delivered torque is more than 70 lbs. (96 N.m).

Criteria No. 3

3rd gear is commanded. Gear ratio is .65-.71 for 3 seconds. Delivered torque is more than 60 lbs. (82 N.m).

Criteria No. 4

4th gear is commanded. Gear ratio is .95-1.05 for 5 seconds. Delivered torque is more than 70 lbs. (96 N.m).

1. Ensure transaxle fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select A/T OUTPUT then select SHIFT TRANS. Monitor current gear and ratio data pairs. Accelerate vehicle and command 1st gear. If gear ratio is not 1.54-1.71, go to next step. If gear ratio is 1.54-1.71, inspect and repair the following. See HYDRA-MATIC 4T80-E OVERHAUL article, then go to step 6 : Lo/Reverse servo apply pin. 1-2 shift valve stuck in upshift position. Forward and/or coast clutch support seals or studs are damaged. Lo roller clutch worn or damaged. Forward clutch piston or seals damaged. Support housing seal rings. Forward sprag damaged or not holding. Check ball missing or stuck.
3. Accelerate vehicle and command 3-4 shift. If gear ratio is not .95-1.05, go to next step. If gear ratio is .95-1.05, inspect and repair the following. See HYDRA-MATIC 4T80-E OVERHAUL article, then go to step 6 : 1-2 shift solenoid valve for debris. 4th band and servo. 3-4 shift valve bore plug is assembled incorrectly.
4. Accelerate vehicle and command 1-2 shift. If gear ratio is not 2.87-3.11, go to next step. If gear ratio is 2.87-3.11, inspect and repair the following. See HYDRA-MATIC 4T80-E OVERHAUL article, then go to step 6 : 1-2 shift solenoid valve for debris. Clutch plates burnt. 1-2 shift valve stuck in 1st gear. 2nd clutch piston, seals or return spring damaged. 2nd sprag not holding.
5. Accelerate vehicle and command 2-3 shift. If gear ratio is not .65-.71, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) . If gear ratio is .65-.71, inspect and repair the following. See HYDRA-MATIC 4T80-E OVERHAUL article, then go to next step: 1-2 shift solenoid valve for debris. Exhaust valve for driven sprocket support installed incorrectly. 3rd clutch plates burnt or damaged. 3rd clutch piston or seals damaged. Check ball missing or stuck.
6. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Test drive vehicle. Ensure transaxle upshifts and downshifts correctly. Select SPECIFIC DTC and enter DTC "P0751". If DTC P0751 is not present, repair is complete. If DTC P0751 is still present, see «CIRCUIT TESTS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) .

Inspect transaxle fluid for sediment or debris. DTC may set about 10 seconds after DTC P0753 has set. If DTC P0753 is also set, repair that DTC before repairing DTC P0751. Repairing condition that caused DTC P0753 to set may eliminate DTC P0751.

DTC P0753: 1-2 SHIFT SOLENOID (ELECTRICAL MALFUNCTION)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

1-2 shift solenoid is used to control transaxle fluid to 1-2 and 3-4 shift valves. Ignition voltage is provided to solenoid through fused circuit. See WIRING DIAGRAMS . Ground is provided by Output Driver Module (ODM) within PCM. PCM monitors voltage levels at ODM. When 1-2 shift solenoid is commanded on, PCM will detect low voltage. When 1-2 shift solenoid is commanded off, PCM will detect ignition voltage. DTC P0753 is set if PCM detects voltage limits which do not meet calibration at anytime.

Conditions For Setting DTC P0753

DTC will set under the following conditions

1. DTC P1650 (ODM) is not present.
2. Engine has been running for more than 5 seconds.
3. PCM detects a circuit problem on 1-2 shift solenoid valve circuits in 5 seconds.

PCM performs the following if DTC is set

1. Will light MIL when fault is set.
2. SERVICE ENGINE SOON, SERVICE TRANSMISSION will be displayed on Drivers Information Center (DIC).
3. Commands 2nd gear.
4. Defaults to line pressure.
5. Disables state and shift adapts.
6. Inhibits TCC engagement.
7. DTC P0753 will be stored in PCM history

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. If DTCs P0758 or P1860 are present, go to next step. If DTCs P0758 or P1860 are not present, go to step 3.
2. Remove and inspect appropriate fuse. See «WIRING DIAGRAMS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e). Replace fuse if necessary. If fuse is blown, check for short to ground in circuit between fuse and transaxle 20-pin connector. If fuse is okay, check for open in circuit between fuse and transaxle 20-pin connector. After repair is complete, go to step 8.
3. Select A/T OUTPUTS, 1-2 SOL. Cycle 1-2 shift solenoid on and off 3 times. If 1-2 shift solenoid valve clicks when cycled on, go to «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e). If 1-2 shift solenoid valve does not click when cycled on, turn ignition off. Disconnect transaxle 20-pin connector. Connect a test light between terminal "A" and terminal "E" of transaxle 20-pin connector (PCM side). (Scheme 96) Turn ignition switch to ON position. DO NOT start engine. If test light is off, go to next step. If test light is on, check for short to ground in 1-2 shift solenoid valve control circuit between transaxle 20-pin connector and PCM. Repair circuit as necessary, then go to step 8. If circuit is okay, replace PCM, then go to step 8.
4. Cycle solenoid on and off 3 times. If test light cycles on and off 3 times, go to next step. If test light does not cycle on and off 3 times, check for an open in 1-2 shift solenoid valve control circuit between transaxle 20-pin connector and PCM. Repair circuit as necessary, then go to step 8. If circuit is okay, and test light is always off, check for short to voltage in 1-2 shift solenoid valve control circuit between transaxle 20-pin connector and PCM. Repair circuit as necessary, then go to step 8. If circuit is okay, replace PCM, then go to step 8.
5. Turn ignition off. Connect Jumper Harness (J-39775) to transaxle side of 20-pin connector. Connect DVOM between terminal "A" and terminal "E" at jumper harness. (Scheme 96) If resistance is 20-40 ohms, go to step 7.
6. If resistance is less than 20 ohms, go to next step. If resistance is more than 40 ohms, check for open in 1-2 shift solenoid valve power and control circuits between transaxle 20-pin connector and solenoid. Repair circuit(s) as necessary, then go to step 8. If circuits are okay, replace 1-2 shift solenoid, then go to step 8.
7. Connect ohmmeter between ground and terminal "A" at jumper harness. If resistance is less than 100 ohms, check for short to ground in circuit between transaxle 20-pin connector and 1-2 shift solenoid. Repair circuit as necessary, then go to next step. If circuit is okay, replace 1-2 shift solenoid, then go to next step. If resistance is more than 100 ohms, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e).
8. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Test drive vehicle and ensure 4th gear is achieved. Select SPECIFIC DTC and enter DTC "P0753". If DTC P0753 is not present, repair is complete. If DTC P0753 is still present, repeat test.

Inspect wiring for poor connections at PCM, 1-2 shift solenoid and at transaxle 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. Check for moisture or corrosion. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P0756: 2-3 SHIFT SOLENOID (PERFORMANCE MALFUNCTION)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS . For fluid circuit identification, see OIL CIRCUIT DIAGRAMS in section No. 1.

PCM identifies a 2-3 shift solenoid problem by monitoring commanded gear ratio and actual gear ratio. DTC P0756 is set if PCM detects a gear ratio outside limits when a particular gear is commanded.

Conditions For Setting DTC P0756

DTC will set under the following conditions

1. DTC P0101, P0102 or P0103 (MAF sensor) is not present.
2. DTC P0121, P0122 or P0123 (throttle position sensor) is not present.
3. DTC P0502 or P0503 (vehicle speed sensor) is not present.
4. DTC P0716 or P0717 (input speed sensor) is not present.
5. DTCs P0753 (1-2 shift solenoid electrical problem) or DTC P0758 (2-3 shift solenoid electrical problem) are not present.
6. DTC P1810 (transaxle fluid pressure valve position switch) is not present.
7. DTC P1860 (TCC PWM solenoid) is not present.
8. Engine has been running for 5 seconds.
9. Vehicle speed is more than 4 MPH.
10. Engine is not in fuel shut off mode.
11. Transaxle temperature is more than 0°F (-18°C).
12. Transaxle shift is not in progress.
13. Throttle angle is more than 11 degrees.
14. Transaxle fluid pressure valve position switch indicates D1, D2, D3 or D4.

PCM performs the following if DTC is set

1. Will light MIL when fault is set.
2. SERVICE ENGINE SOON, SERVICE TRANSMISSION will be displayed on Drivers Information Center (DIC).
3. Commands 2nd gear.
4. Defaults to line pressure.
5. Disables state and shift adapts.
6. Inhibits TCC engagement.
7. DTC P0756 will be stored in PCM history.

DTC has 4 different failure criteria. These criteria are as follows

1st gear is commanded. Gear ratio is .65-.71 for one second. Delivered torque is more than 60 lbs. (82 N.m).

2nd gear is commanded. Gear ratio is .95-1.05 for .5 seconds. Delivered torque is more than 60 lbs. (82 N.m).

3rd gear is commanded. Gear ratio is 1.54-1.71 for 4 seconds. Delivered torque is more than 60 lbs. (82 N.m).

4th gear is commanded. Gear ratio is 2.87-3.11 for one second. Delivered torque is more than 12 lbs. (15 N.m).

1. Ensure transaxle fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select A/T OUTPUT then select SHIFT TRANS. Monitor current gear and ratio data pairs. Accelerate vehicle and command 1st gear. If gear ratio is not .65-.71, go to next step. If gear ratio is .65-.71, inspect and repair the following. See HYDRA-MATIC 4T80-E OVERHAUL article, then go to step 6 : Lo/Reverse servo apply pin. 2-3 shift valve stuck. Forward clutch support studs are damaged. Lo roller clutch worn or damaged. Forward clutch piston or seals damaged. Support housing seal rings. Forward sprag damaged or not holding. Check ball No. 8 missing.
3. Accelerate vehicle and command 1-2 shift. If gear ratio is not .95-1.05, go to next step. If gear ratio is .95-1.05, inspect and repair the following. See HYDRA-MATIC 4T80-E OVERHAUL article, then go to step 6 : 2nd clutch plates burnt. 2nd clutch piston or seals damaged. 2-3 shift solenoid valve stuck. 2nd clutch return spring and retainer assembly broken or out of position.
4. Accelerate vehicle and command 2-3 shift. If gear ratio is not 1.54-1.71 go to next step. If gear ratio is 1.54-1.71, inspect and repair the following. See HYDRA-MATIC 4T80-E OVERHAUL article, then go to step 6 : 3-4 shift valve bore plug is assembled incorrectly. Exhaust valve for driven sprocket support installed incorrectly. 3rd clutch plates burnt or damaged. 3rd clutch piston or seals damaged. Check ball missing or stuck. Debris in 2-3 shift solenoid valve.
5. Accelerate vehicle and command 3-4 shift. If gear ratio is not 2.87-3.11, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) . If gear ratio is 2.87-3.11, inspect and repair the following. See HYDRA-MATIC 4T80-E OVERHAUL article, then go to next step: Debris in 2-3 shift solenoid valve. 4th band or 4th servo. 3-4 shift valve bore plug is assembled incorrectly.
6. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Test drive vehicle. Ensure transaxle upshifts and downshifts correctly. Select SPECIFIC DTC and enter DTC "P0756". If DTC P0756 is not present, repair is complete. If DTC P0756 is still present, see appropriate «CIRCUIT TESTS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) .

Inspect transaxle fluid for sediment or debris. Driver may experience an engine flair or neutral in 4th gear.

DTC P0758: 2-3 SHIFT SOLENOID (ELECTRICAL MALFUNCTION)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

2-3 shift solenoid is used to control transaxle fluid to 1-2 and 2-3 shift valves. Ignition voltage is provided to solenoid through fused circuit. See WIRING DIAGRAMS . Ground is provided by Output Driver Module (ODM) within PCM. PCM monitors voltage levels at ODM. When 2-3 shift solenoid is commanded on, PCM will detect low voltage. When 2-3 shift solenoid is commanded off, PCM will detect ignition voltage. DTC P0758 is set if voltage limits do not meet calibration at anytime.

Conditions For Setting DTC P0758

DTC will set under the following conditions

1. DTC P1650 (ODM) is not present.
2. Engine has been running for more than 5 seconds.
3. PCM detects an open, short to ground or short to voltage on 2-3 shift solenoid valve circuits within 5 seconds.

PCM performs the following if DTC is set

1. Will light MIL when fault is set.
2. SERVICE ENGINE SOON, SERVICE TRANSMISSION will be displayed on Drivers Information Center (DIC).
3. Commands 2nd gear.
4. Defaults to line pressure.
5. Disables steady state and shift adapts.
6. Inhibits TCC engagement.
7. DTC P0758 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. If DTCs P0753 or P1860 are present, go to next step. If DTCs P0753 or P1860 are not present, go to step 3.
2. Remove and inspect appropriate fuse. See «WIRING DIAGRAMS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e). Replace fuse if necessary. If fuse is blown, check for short to ground in circuit between fuse and transaxle 20-pin connector. If fuse is okay, check for open in circuit between fuse and transaxle 20-pin connector. After repair is complete, go to step 8.
3. Select A/T OUTPUTS, 2-3 SOL. Cycle 2-3 shift solenoid on and off 3 times. If 2-3 shift solenoid valve clicks when cycled on, go to «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e). If 2-3 shift solenoid valve does not click when cycled on, turn ignition off. Disconnect transaxle 20-pin connector. Connect a test light between terminal "B" and terminal "E" of transaxle 20-pin connector (PCM side). (Scheme 96) Turn ignition switch to ON position. DO NOT start engine. If test light is off, go to next step. If test light is on, check for short to ground in 2-3 shift solenoid valve control circuit between transaxle 20-pin connector and PCM. Repair circuit as necessary, then go to step 8. If circuit is okay, replace PCM, then go to step 8.
4. Cycle solenoid on and off 3 times. If test light cycles on and off 3 times, go to next step. If test light does not cycle on and off 3 times, check for an open in 2-3 shift solenoid valve control circuit between transaxle 20-pin connector and PCM. Repair circuit as necessary, then go to step 8. If circuit is okay, and test light is always off, check for short to voltage in 2-3 shift solenoid valve control circuit between transaxle 20-pin connector and PCM. Repair circuit as necessary, then go to step 8. If circuit is okay, replace PCM, then go to step 8.
5. Turn ignition off. Connect Jumper Harness (J-39775) to transaxle side of 20-pin connector. Connect DVOM between terminal "B" and terminal "E" at jumper harness. (Scheme 96) If resistance is 20-40 ohms, go to step 7.
6. If resistance is less than 20 ohms, go to next step. If resistance is more than 40 ohms, check for open in 2-3 shift solenoid valve power and control circuits between transaxle 20-pin connector and solenoid. Repair circuit(s) as necessary, then go to step 8. If circuits are okay, replace 2-3 shift solenoid, then go to step 8.
7. Connect ohmmeter between ground and terminal "B" at jumper harness. If resistance is less than 100 ohms, check for short to ground in circuit between transaxle 20-pin connector and 2-3 shift solenoid. Repair circuit as necessary, then go to next step. If circuit is okay, replace 2-3 shift solenoid, then go to next step. If resistance is more than 100 ohms, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e).
8. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Test drive vehicle and ensure 4th gear is achieved. Select SPECIFIC DTC and enter DTC "P0758". If DTC P0758 is not present, repair is complete. If DTC P0758 is still present, repeat test.

Inspect wiring for poor connections at PCM, 2-3 shift solenoid and at transaxle 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. Check for moisture or corrosion. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P1810: TFP VALVE POSITION SWITCH (CIRCUIT MALFUNCTION)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS . For fluid circuit identification, see OIL CIRCUIT DIAGRAMS in section No. 1.

Transaxle Fluid Pressure (TFP) valve position switch consists of 5 normally open switches. Ignition voltage is applied to each of these switches. By grounding one or more of these switches with fluid pressure from valve, PCM can detect which gear range is selected. DTC P1810 is set if PCM detects an invalid combination of TFP valve position switch applications.

Conditions For Setting DTC P1810

DTC will set under the following conditions

1. DTC P0101, P0102 or P0103 (MAF sensor) is not present.
2. DTC P0121, P0122 or P0123 (throttle position sensor) is not present.
3. DTC P0502 or P0503 (vehicle speed sensor) is not present.
4. DTC P0716 or P0717 (input speed sensor) is not present.
5. Ignition voltage is 10-17 volts.
6. Engine has been running for more than 5 seconds.
7. Engine is not in fuel shut off mode.

PCM performs the following if DTC is set

1. Will light MIL when fault is set.
2. SERVICE ENGINE SOON, SERVICE TRANSMISSION will be displayed on Drivers Information Center (DIC).
3. Substitutes value of previous TFP valve position switch, if consistent with Park/Neutral status.
4. Commands default line pressure.
5. Disables state and shift adapts.
6. Inhibits TCC engagement.
7. DTC P1810 will be stored in PCM history.

DTC has 5 different failure criteria. These criteria are as follows

An illegal TFP valve position switch value of 000 or 010 exists for 4 minutes and 10 seconds.

Vehicle speed is more than 5 MPH. Throttle angle is more than 11 degrees. Delivered torque is 80-200 ft. lbs. (109-270 N.m). TFP valve position switch shows Park/Neutral and gear ratio indicates Reverse or Drive for 5 seconds.

Vehicle speed is more than 5 MPH. Throttle angle is more than 11 degrees. Delivered torque is 80-200 ft. lbs. (109-270 N.m). TFP valve position switch shows Reverse and gear ratio indicates Drive for 7 seconds.

Vehicle speed is more than 5 MPH. Throttle angle is more than 7 degrees. Delivered torque is 30-150 ft. lbs. (38-188 N.m). TFP valve position switch shows D4, D3, D2 or D1 and gear ratio indicates Reverse for 3 seconds.

Criteria No. 5

Engine is off. TFP valve position switch shows D2 and does not indicate Park/Neutral in 4.95 seconds after engine running. Vehicle speed is less than 5 MPH. Transaxle fluid temperature is more than 0°F (-18°C). Discontinue criteria No. 5 if engine is running for 5 seconds.

1. Ensure fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. NOTE: All TFP valve position switch parameters will be given in A/B/C order (Example: ON/OFF/ON). Scan tool will display ON and OFF. ON switch is closed and OFF switch is open.
2. Select "TFT SWITCH A/B/C" on scan tool and capture TFP VAL POSITION SW data parameter. Disconnect transaxle 20-pin connector. If TFP valve position switch parameters are Off/Off/Off, go to step 9 . If TFP valve position switch parameters are On/Off/Off, inspect and repair short to ground in transaxle range "A" input circuit between transaxle 20-pin connector and PCM, then go to step 24 . If circuit is okay, replace PCM, then go to step 24 . If TFP valve position switch parameters are not On/Off/Off or Off/Off/Off, go to next step.
3. If TFP valve position switch parameters are Off/On/Off, inspect and repair short to ground in transaxle range "B" input circuit between transaxle 20-pin connector and PCM, then go to step 24 . If circuit is okay, replace PCM, then go to step 24 . If TFP valve position switch parameters are not Off/On/Off, go to next step.
4. If TFP valve position switch parameters are Off/Off/On, inspect and repair short to ground in transaxle range "C" input circuit between transaxle 20-pin connector and PCM, then go to step 24 . If circuit is okay, replace PCM, then go to step 24 . If TFP valve position switch parameters are not Off/Off/On, go to next step.
5. If TFP valve position switch parameters are On/On/Off, inspect and repair short to ground or wires shorted together in transaxle range "A" and "B" input circuits between transaxle 20-pin connector and PCM, then go to step 24 . If circuit is okay, replace PCM, then go to step 24 . If TFP valve position switch parameters are not On/On/Off, go to next step.
6. If TFP valve position switch parameters are On/Off/On, inspect and repair short to ground or wires shorted together in transaxle range "A" and "C" input circuits between transaxle 20-pin connector and PCM, then go to step 24 . If circuit is okay, replace PCM, then go to step 24 . If TFP valve position switch parameters are not On/Off/On, go to next step.
7. If TFP valve position switch parameters are Off/On/On, inspect and repair short to ground or wires shorted together in transaxle range "B" and "C" input circuits between transaxle 20-pin connector and PCM, then go to step 24 . If circuit is okay, replace PCM, then go to step 24 . If TFP valve position switch parameters are not Off/On/On, go to next step.
8. If TFP valve position switch parameters are not Off/On/On, inspect and repair short to ground or wires shorted together in transaxle range "A", "B" and "C" input circuits between transaxle 20-pin connector and PCM, then go to step 24 . If circuits are okay, replace PCM, then go to step 24 .
9. Connect Jumper Harness (J-39775) to PCM side of 20-pin connector. Using Test Adapter Kit (J-35616), connect fused jumper wire between terminal "N" of jumper harness and ground. If TFP valve position switch parameters are not On/Off/Off and are Off/Off/Off, inspect and repair open in transaxle range "A" input circuit between transaxle 20-pin connector and PCM, then go to step 24 . If circuit is okay, replace PCM, then go to step 24 . If TFP valve position switch parameters are not Off/Off/Off, go to next step. If TFP valve position switch parameters are On/Off/Off, go to step 12 .
10. If TFP valve position switch parameters are not On/On/Off, inspect and repair wires shorted together in transaxle range "A" and "C" input circuit between transaxle 20-pin connector and PCM, then go to step 24 . If circuit is okay, replace PCM, then go to step 24 . If TFP valve position switch parameters are On/On/Off, go to next step.
11. If TFP valve position switch parameters are not On/On/Off, inspect and repair wires shorted together in transaxle range "A" and "B" input circuit between transaxle 20-pin connector and PCM, then go to step 24 . If circuit is okay, replace PCM, then go to step 24 . If TFP valve position switch parameters are Off/On/Off, go to next step.
12. Connect fused jumper wire between terminal "R" of jumper harness and ground. If TFP valve position switch parameters are not Off/On/Off and are Off/Off/Off, inspect and repair open in transaxle range "B" input circuit between transaxle 20-pin connector and PCM, then go to step 24 . If circuit is okay, replace PCM, then go to step 24 . If TFP valve position switch parameters are not Off/Off/Off, go to next step. If TFP valve position switch parameters are Off/On/Off, go to step 15 .
13. If TFP valve position switch parameters are Off/On/On, inspect and repair wires shorted together in transaxle range "A" and "B" input circuit between transaxle 20-pin connector and PCM, then go to step 24 . If circuit is okay, replace PCM, then go to step 24 . If TFP valve position switch parameters are not Off/On/On, go to next step.
14. If TFP valve position switch parameters are Off/On/On, inspect and repair wires shorted together in transaxle range "B" and "C" input circuit between transaxle 20-pin connector and PCM, then go to step 24 . If circuit is okay, replace PCM, then go to step 24 . If TFP valve position switch parameters are not Off/On/On, go to next step.
15. Connect fused jumper wire between terminal "P" of jumper harness and ground. If TFP valve position switch parameters are not Off/Off/On, inspect and repair open in transaxle range "C" input circuit between transaxle 20-pin connector and PCM, then go to step 24 . If circuit is okay, replace PCM, then go to step 24 . If TFP valve position switch parameters are not Off/Off/Off, go to next step. If TFP valve position switch parameters are Off/Off/On, go to step 18 .
16. If TFP valve position switch parameters are Off/On/On, inspect and repair wires shorted together in transaxle range "A" and "B" input circuit between transaxle 20-pin connector and PCM, then go to step 24 . If circuit is okay, replace PCM, then go to step 24 . If TFP valve position switch parameters are not Off/On/On, go to next step.
17. If TFP valve position switch parameters are On/Off/On, inspect and repair wires shorted together in transaxle range "A" and "C" input circuit between transaxle 20-pin connector and PCM, then go to step 24 . If circuit is okay, replace PCM, then go to step 24 . NOTE: If any circuit in transaxle wiring harness needs repair between transaxle 20-pin connector and TFP valve position switch, transaxle wiring harness MUST be replaced as an assembly.
18. Disconnect Jumper Harness (J-39775) from PCM side and connect to transaxle side of 20-pin connector. Connect DVOM between terminal "N" of jumper harness and ground. If resistance is more than 1000 ohms, go to next step. If resistance is less than 1000 ohms, inspect and repair short to ground in transaxle range "A" input circuit between transaxle 20-pin connector and TFP valve position switch, then go to step 24 . If circuit is okay, replace TFP valve position switch, then go to step 24 .
19. Connect DVOM between terminal "R" of jumper harness and ground. If resistance is more than 1000 ohms, go to next step. If resistance is less than 1000 ohms, inspect and repair short to ground in transaxle range "B" input circuit between transaxle 20-pin connector and TFP valve position switch, then go to step 24 . If circuit is okay, replace TFP valve position switch, then go to step 24 .
20. Connect DVOM between terminal "P" of jumper harness and ground. If resistance is more than 1000 ohms, go to next step. If resistance is less than 1000 ohms, inspect and repair short to ground in transaxle range "C" input circuit between transaxle 20-pin connector and TFP valve position switch, then go to step 24 . If circuit is okay, replace TFP valve position switch, then go to step 24 .
21. Start engine and allow to idle. Place gear selector in "R" position. Connect DVOM between terminal "N" of jumper harness and ground. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, inspect and repair open in transaxle range "A" input circuit between transaxle 20-pin connector and TFP valve position switch, then go to step 24 . If circuit is okay, replace TFP valve position switch, then go to step 24 .
22. Move gear selector to "D3" position. Connect DVOM between terminal "R" of jumper harness and ground. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, inspect and repair open in transaxle range "B" input circuit between transaxle 20-pin connector and TFP valve position switch, then go to step 24 . If circuit is okay, replace TFP valve position switch, then go to step 24 .
23. Move gear selector to "D4" position. Connect DVOM between terminal "P" of jumper harness and ground. If resistance is more than 5 ohms, inspect and repair open in transaxle range "C" input circuit between transaxle 20-pin connector and TFP valve position switch, then go to next step. If circuit is okay, replace TFP valve position switch, then go to next step. If resistance is less than 5 ohms, replace PCM, then go to next step.
24. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Road test vehicle in all gears. With vehicle in OD accelerate with throttle angle more than 12 degrees. Vehicle speed must be more than 5 MPH. Engine torque must be 80-200 ft. lbs. (109-270 N.m). Select SPECIFIC DTC and enter DTC "P1810". If DTC P1810 is not present, repair is complete. If DTC P1810 is still present, repeat test.

Inspect wiring for poor connections at PCM, TFP valve position switch and at transaxle 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change. Diagnose DTC P1520 first if present. Inspect TFP valve position switch for debris. If transaxle overhaul was performed, ensure fluid level is correct. A low fluid condition may set DTC P1810.

DTC P1811: MAXIMUM ADAPT & LONG SHIFT

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

An adaptive modifier modifies transaxle pressure. Adaptive modifier controls shift execution time. This DTC checks time required to accomplish the shift. If shift takes more than .55 seconds, and adaptive modifier cannot shorten this time, counter increases by one. DTC P1811 is set if PCM detects when this counter reaches its limit.

Conditions For Setting DTC P1811

DTC will set under the following conditions

1. DTC P0121, P0122 or P0123 (throttle position sensor) is not present.
2. DTC P0218 (transaxle fluid overheating) is not present.
3. DTC P0502 or P0503 (vehicle speed sensor) is not present.
4. DTCs P0711, P0712 or P0713 (transaxle fluid temperature) are not present.
5. TFT is more than 122°F (50°C).
6. Vehicle speed is more than 10 MPH.
7. Throttle angle is more than 15.7 degrees.

PCM performs the following if DTC is set

1. Will not light MIL when fault is set.
2. SERVICE ENGINE SOON, SERVICE TRANSMISSION will be displayed on Drivers Information Center (DIC).
3. Commands maximum line pressure.
4. Disables all adapts.
5. DTC P1811 will be stored in PCM history.

DTC has 3 different failure criteria. These criteria are as follows

1-2 shift is longer than .55 seconds and 1-2 shift adapt has reached it's limit.

2-3 shift is longer than .55 seconds and 2-3 shift adapt has reached it's limit.

3-4 shift is longer than .55 seconds and 3-4 shift adapt has reached it's limit.

1. Ensure transaxle fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test. If other DTCs are present, repair those DTCs first, then go to step 8 .
2. Select SPECIFIC DTC and enter ADAPTS on scan tool. Review Transaxle Adapt Pressure (TAP) data and compare parameters. See 1-2 ADAPTS table. 1-2 ADAPTS Parameter Specification 1-2 TAP Low -30 Or +30 PSI 1-2 TAP High -30 Or +30 PSI 1-2 Shift Time .55 Seconds If data parameters are equal to or more than specified, inspect and repair the following, then go to step 8 . Low line pressure. Pressure control solenoid clamp broken, causing leak. Pressure control solenoid stuck on. 2nd clutch assembly. 2nd sprag clutch. 1-2 shift solenoid valve. 1-2 shift valves. See HYDRA-MATIC 4T80-E OVERHAUL article. If data parameters are less than specified, go to next step.
3. Review data and compare parameters. See 2-3 ADAPTS table. 2-3 ADAPTS Parameter Specification 2-3 TAP Low -30 Or +30 PSI 2-3 TAP High -30 Or +30 PSI 2-3 Shift Time .55 Seconds If data parameters are equal to or more than specified, inspect and repair the following, then go to step 8 Low line pressure. Pressure control solenoid clamp broken, causing leak. Pressure control solenoid stuck on. 3-4 shift valve bore plug is assembled incorrectly. Exhaust valve for driven sprocket support installed incorrectly. 3rd clutch plates burnt or damaged. 3rd clutch piston or seals damaged. Check ball missing or stuck. See HYDRA-MATIC 4T80-E OVERHAUL article. If data parameters are less than specified, go to next step.
4. Review data and compare parameters. See 3-4 ADAPTS table. 3-4 ADAPTS Parameter Specification 3-4 TAP Low -30 Or +30 PSI 3-4 TAP High -30 Or +30 PSI 3-4 Shift Time .55 Seconds If data parameters are equal to or more than specified, inspect and repair the following, then go to step 8 : Low line pressure. Pressure control solenoid clamp broken, causing leak. Pressure control solenoid stuck on. 4th band or 4th servo. 3-4 shift valve bore plug is assembled incorrectly. See HYDRA-MATIC 4T80-E OVERHAUL article. If data parameters are less than specified, go to next step.
5. Connect oil pressure gauge to line pressure test port. See HYDRAULIC PRESSURE TESTS in HYDRA-MATIC 4T80-E OVERHAUL article. Select A/T OUTPUTS then PC SOL on scan tool. Start engine and allow to idle in Park position. Increase and decrease PC solenoid valve amperage and record values. See PCS SPECIFICATIONS table. PCS SPECIFICATIONS Amperage PSI .10 240-260 .20 210-250 .30 190-240 .40 175-210 .50 150-200 .60 125-175 .70 110-160 .80 80-130 .90 75-125 If scan tool shows specified pressure at amperage, see «DIAGNOSTIC AIDS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e) . If pressures are low, go to next step. If pressures are high, go to step 7 .
6. Inspect and repair the following. See HYDRA-MATIC 4T80-E OVERHAUL article, then go to next step. Scavenge pump body is leaking at gasket or pump body. Scavenge pipe is restricted. Scavenge pipe seal is cut or leaking. Primary pump body is leaking at gasket or pump body. Scavenge screens are clogged. Pressure regulator valve is stuck due to sediment. Secondary pump body is leaking at gasket or pump body. Transaxle fluid level is low. Cooler lines are clogged or restricted.
7. Inspect and repair the following. See HYDRA-MATIC 4T80-E OVERHAUL article, then go to next step. Pressure regulator valve is stuck due to sediment or undersized bore. Pressure control solenoid feed valve is stuck. Pressure regulator boost valve is stuck open. Ball check valve is missing. Final drive internal gear snap ring is missing. Actuator feed limit valve is stuck open.
8. After repair is complete, select DTC on scan tool. Select CLEAR INFO function then A/T RESET ADAPTS. Road test vehicle in "D4". Ensure ATF is more than 122°F (50°C), TP angle is more than 15.7 degrees and vehicle speed is more than 10 MPH. Vehicle must shift 1-2, 2-3 and 3-4 in .55 seconds 3 times. Select SPECIFIC DTC and enter DTC "P1811". If DTC P1811 is not present, repair is complete. If DTC P1811 is still present, repeat test.

Ensure PCM has latest update. If transaxle overhaul was performed, using scan tool, clear all adapts.

DTC P1814: TORQUE CONVERTER OVERSTRESS

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS . For fluid circuit identification, see OIL CIRCUIT DIAGRAMS in section No. 1.

DTC P1814 detects high throttle angle and low vehicle speed in Drive or Reverse. DTC P1814 is used to record failure data because this condition can damage powertrain or create an unsafe condition.

Conditions For Setting DTC P1814

DTC will set under the following conditions

1. DTC P0121, P0122 or P0123 (throttle position sensor) is not present.
2. DTC P0502 or P0503 (vehicle speed sensor) is not present.
3. DTC P0716 or P0717 (input speed sensor) is not present.
4. DTC P1810 (TFP valve position switch) is not present.
5. TCC slip speed is more than 1504 RPM.
6. Vehicle speed is less than 5 MPH.
7. Transaxle is in Drive or Reverse.
8. Throttle angle is more than 65 degrees for 12 seconds.

PCM performs the following if DTC is set

1. Will not light MIL when fault is set.
2. DTC P1814 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. If DTC 1814 failure counter is more than "1", replace transaxle fluid and scavenge screens. Reset transaxle oil life, then go to next step. See appropriate AUTOMATIC TRANSMISSION SERVICING article in TRANSMISSION SERVICING. If DTC 1814 failure counter is "1", inspect and repair transaxle fluid condition and level, then go to next step.
3. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Drive vehicle in "D4" with TCC slip less than 1504 RPM, throttle angle less than 65 percent and vehicle speed more than 5 MPH. Conditions must occur for more than 12 seconds. Select SPECIFIC DTC and enter DTC "P1814". If DTC P1814 is not present, repair is complete. If DTC P1814 is still present, repeat test.

Accelerating and applying brakes at same time may set DTC P1814.

DTC P1860: TCC PULSE WIDTH MODULATED (PWM) SOLENOID (ELECTRICAL MALFUNCTION)

Note. Perform OBD system check prior to performing diagnostic procedures. For wire circuit identification, see WIRING DIAGRAMS .

Torque Converter Clutch (TCC) fluid is regulated for apply and release by TCC Pulse Width Modulated (PWM) solenoid. When solenoid is commanded off, PCM will detect high voltage. When solenoid is commanded on, PCM will detect low voltage. DTC P1860 is set if PCM detects voltage limits that do not meet calibration at anytime.

Conditions For Setting DTC P1860

DTC will set under the following conditions

1. DTC P1650 (ODM) is not present.
2. Engine running for more than 5 seconds.
3. TCC duty cycle is less than 10 percent or more than 85 percent.
4. PCM detects an open, short to ground or short to voltage on TCC PWM solenoid valve circuit within 5 seconds.

PCM performs the following if DTC is set

1. Will light MIL at first failure signal.
2. SERVICE ENGINE SOON, SERVICE TRANSMISSION will be displayed on Drivers Information Center (DIC).
3. Inhibits TCC engagement.
4. Inhibits 4th gear if transaxle is in hot mode.
5. DTC P1860 will be stored in PCM history.

1. Ensure transaxle fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Turn ignition off. Disconnect transaxle 20-pin connector. Connect a test light between terminal "U" and terminal "T" of transaxle 20-pin connector (PCM side). (Scheme 96) Turn ignition switch to ON position. DO NOT start engine. If test light is off, go to next step. If test light is on, check and repair short to ground in TCC PWM solenoid control circuit between transaxle 20-pin connector and PCM. Repair circuit as necessary, then go to step 6. If circuit is okay, replace PCM, then go to step 6.
3. Select A/T OUTPUTS then TCC ENABLE on scan tool. Cycle TCC solenoid valve ON and OFF 3 times. If test light cycles on and off 3 times, go to next step. If test light stays off, check and repair open in TCC PWM solenoid control circuit between PCM and fuse block, then go to step 6. See «WIRING DIAGRAMS»(/cadillac/deville-concours/i-final-1999-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t80-e). If test light stays on, check and repair short to voltage in TCC PWM solenoid control circuit between PCM and TCC PWM solenoid valve. If circuit is okay, replace PCM, then go to step 6.
4. Connect Jumper Harness (J-39775) to transaxle side of 20-pin connector. Connect DVOM between terminal "U" and terminal "T" of jumper harness. If resistance is 10-15 ohms, replace PCM, then go to step 6. If resistance is more than 15 ohms, inspect and repair open in TCC PWM solenoid control circuit between PCM and 20-pin connector, then go to step 6. If circuit is okay, replace TCC PWM solenoid control valve, then go to step 6. If resistance is less than 15 ohms, go to next step.
5. Connect DVOM between terminal "T" of jumper harness and ground. If resistance is less than 100 ohms, inspect and repair short to ground between terminal "T" and ground, then go to next step. If circuit is okay, replace TCC PWM solenoid control valve, then go to next step. If resistance is more than 100 ohms, replace TCC PWM solenoid control valve, then go to next step.
6. After repair is complete, select DTC on scan tool. Select CLEAR INFO function. Road test vehicle and ensure TCC applies. Increase vehicle speed until TCC enable turns on. Ensure TCC duty cycle is 10-85 percent for more than 5 seconds. Select SPECIFIC DTC and enter DTC "P1860". If DTC P1860 is not present, repair is complete. If DTC P1860 is still present, repeat test.

Inspect wiring for poor connections at PCM, TCC PWM solenoid and at transaxle 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Check for broken wire inside insulation. Check for moisture or corrosion. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change. Ensure transaxle fluid level is correct.

POWERTRAIN CONTROL MODULE (PCM)

Note. Before replacing PCM, carefully inspect all wiring and control components. Failure to test for short circuits may result in repeated PCM failure due to shorts. To prevent internal damage to PCM, ensure ignition switch is in OFF position when connecting or disconnecting PCM connectors or any electrical components.

Removal & Installation

Turn ignition off. Disconnect negative battery cable. Locate PCM. On Aurora, PCM is located behind right side sound insulator, under instrument panel. On Cadillac models, PCM is located in left front corner of engine compartment under air cleaner housing. On all models, remove any necessary components to gain access to PCM. Disconnect harness connectors from PCM. Remove PCM mounting bolts (if equipped). Remove PCM. To install, reverse removal procedure. Transfer any necessary components (i.e., knock sensor module, EEPROM, etc.) to new PCM before installation. Program replacement PCM using appropriate equipment and latest software. See COMPUTER RELEARN PROCEDURES article in APPLICATIONS & IDENTIFICATION.

1999 Aurora (4.0L) 4T80-E Transaxle System Wiring Diagram. Scheme 99

1999 DeVille & Eldorado (4.6L) 4T80-E Transaxle System Wiring Diagram. Scheme 100

1999 Seville (4.6L) 4T80-E Transaxle System Wiring Diagram. Scheme 101

See also:
• CLUTCH & BAND APPLICATION (4T80-E)
• DIAGNOSTIC TESTS
• DIAGNOSTIC AIDS
• CLEARING DIAGNOSTIC TROUBLE CODES
• NO DATA LINK CONNECTOR (DLC) DATA
• P0218
• P0502
• P0711
• P0712
• P0713
• P0716
• P0717
• P0719
• P0724
• P0730
• P0741
• P0742
• P0748
• P0751
• P0753
• P0756
• P0758
• P1810
• P1811
• P1814
• P1860
• RETRIEVING DIAGNOSTIC TROUBLE CODES