Automatic Transaxle Diagnosis - 4t60-e Buick Riviera VIII

APPLICATION

4T60-E APPLICATION

DESCRIPTION

The 4T60-E transaxle uses 2 electric solenoids to control transaxle upshifts and downshifts. 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.

OPERATION

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 CHART (4T60-E) .

PCM

On "W" body models, PCM is located at right side of engine compartment. On all other models, PCM is located under right kick 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 upshifts and downshifts based on coolant temperature (or transaxle temperature), throttle position, transaxle range switch position, vehicle speed sensor and brake pedal switch. System also includes several other switches and sensors which are used for engine control. These components are covered in ENGINE PERFORMANCE.

SOLENOIDS

Transaxle is shifted up or down by 2 electric solenoids. Both solenoids are located on valve body. Ignition power is supplied to each solenoid by fused circuit. See WIRING DIAGRAMS .

Solenoid "A" controls hydraulic pressure to 1-2 and 3-4 shift valves. Solenoid "B" controls hydraulic pressure to 3-2 and 4-3 shift valves.

SELF-DIAGNOSTICS

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 factory recommended Tech 1 scan tool or aftermarket 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 the appropriate TESTS W/CODES article in ENGINE PERFORMANCE.

TROUBLE SHOOTING

Note. For trouble shooting procedures, see TROUBLE SHOOTING in AUTO TRANS OVERHAUL - 4T60-E article.

CLUTCH & BAND APPLICATIONS

CLUTCH & BAND APPLICATION (4T60-E)

SELF-DIAGNOSTIC SYSTEM

Note. To test electronic control of transaxle solenoids without using self-diagnostics or if self-diagnostics does not function, see COMPONENT TESTS under ELECTRONIC TESTING. After repairs are made, DTCs should be erased from computer memory. See CLEARING TROUBLE CODES .

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.

RETRIEVING CODES

Note. Stored DTCs may be retrieved from PCM memory using a factory recommended Tech 1 scan tool or aftermarket scan tool. DTCs CANNOT be retrieved by grounding 16-pin Data Link Connector (DLC). Plugging scan tool into DLC, located under 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.

TROUBLE CODE DEFINITIONS

Note. Only transaxle-related trouble codes are listed. For engine-related DTCs, see TROUBLE CODE DEFINITIONS in appropriate SELF-DIAGNOSTICS (TESTS W/CODES) article in the 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.

PCM TROUBLE CODE DEFINITIONS

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 CODES»(/buick/riviera/viii-1994-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t60-e__retrieving-codes) . Read and record all stored DTCs. Exit diagnostic mode and clear trouble codes. See «CLEARING TROUBLE CODES»(/buick/riviera/viii-1994-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t60-e__clearing-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.

CLEARING TROUBLE CODES

DTCs can be cleared using scan tool. If scan tool is not available, turn ignition switch to OFF position. Remove control module fuse from fuse block for 30 seconds. Replace fuse. If fuse cannot be located, disconnect PCM pigtail at battery for 30 seconds. Codes 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.

Scheme 57

1. Check PCM memory for trouble codes. If present, perform all tests and correct any PCM related trouble codes. Warm transaxle to normal operating temperature.
2. Using Transaxle Test Box (J-38791), connect test harness between transaxle case connector and engine harness connector. (Scheme 57) Connect a bidirectional scan tool or Tech 1 (94-00101 A) to DLC. CAUTION: DO NOT accelerate vehicle from a standing start in 3rd or 4th gear. DO NOT shift into 1st gear above 25 MPH. DO NOT "brake torque" vehicle with test box tool attached. DO NOT engage TCC below 25 MPH. DO NOT manually shift into 1st, 2nd or 3rd gear with test box attached.
3. Turn ignition on. If necessary, input vehicle information on scan tool. Place gear selector and TCC switches on test box to normal position. Follow test procedures outlined in TEST BOX DIAGNOSTIC FLOW CHART. (Scheme 58)
4. Road test vehicle and note LED indicators on test box. If a problem is present (indicated by test box LEDs), TEST BOX DIAGNOSTIC FLOW CHART will refer you to next procedure or chart. (Scheme 59)-6. See appropriate procedures under «COMPONENT TESTS»(/buick/riviera/viii-1994-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t60-e__component-tests-with-test-box).

COMPONENT TESTS (WITH TEST BOX)

Note. Before using following charts, see TESTING EQUIPMENT & PROCEDURES .

Scheme 58

Scheme 59

Scheme 60

Scheme 61

Scheme 62

COMPONENT TEST (WITHOUT TEST BOX)

Note. The following test will determine if an electrical problem exists in transaxle or vehicle.

Scheme 63

DIAGNOSTIC TESTS

Note. Proceed to displayed DTC. Not all DTCs are applicable to all models.

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

DIAGNOSTIC AIDS

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.

ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK

Note. Use of Tech 1 scan tool is required to perform OBD system check. Perform this test prior to performing any diagnostic procedures in DTC tests.

The OBD System Check determines

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 TESTS W/O CODES article in ENGINE PERFORMANCE.

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

2.4L

1. Turn ignition on, with engine off. Observe Malfunction Indicator Light (MIL). If MIL lights, go to next step. If MIL does not light, see A-1, MIL INOPERATIVE in «BASIC TESTING - 2.4L»(ref-20287) article in ENGINE PERFORMANCE.
2. Turn ignition off. Install scan tool and follow scan tool manufacturer's instructions to proceed with test. Turn ignition on. If scan tool displays PCM data, go to next step. If scan tool does not display PCM data, see A-4, NO SCAN TOOL DATA in «BASIC TESTING - 2.4L»(ref-20287) article.
3. Using scan tool, command MIL off. If MIL remains on, see A-2, MIL INOPERATIVE in «BASIC TESTING - 2.4L»(ref-20287) article. If MIL is off, using scan tool, check for any DTCs stored in current, history or MIL request. If any DTC is stored, go to next step. If no DTCs are stored, go to step 5.
4. Using scan tool, save freeze frame and failure record information using "Capture Info" feature. If any DTC is indicated as "LAST TST FAILED", diagnose DTC. If DTC is not stored, check related circuit or component(s). See «SYSTEM/COMPONENT TESTS - 2.4L»(ref-20357) article.
5. Attempt to start engine. If engine starts and runs, go to next step. If engine does not start or starts and dies, see NO START DIAGNOSIS (A-3) in «BASIC TESTING - 2.4L»(ref-20287) article.
6. Turn ignition on, with engine off. Using scan tool, follow scan tool manufacturer's instructions to proceed with test. Check coolant temperature sensor and throttle position sensor operation. Start engine. Allow engine to reach normal operating temperature. Check coolant temperature, oxygen and manifold absolute pressure sensors and idle air control valve values.
7. Repair related circuit or component(s) as necessary. See «SYSTEM/COMPONENT TESTS - 2.4L»(ref-20357) article. If all components are okay, see «TESTS W/O CODES»(/buick/riviera/viii-1994-1999/remont/testing-diagnostics/#engine-control-system-tests-wo-codes) article.

3.1L & 3.4L

1. Turn ignition on with engine off. Observe Malfunction Indicator Light (MIL). If MIL lights, go to next step. If MIL does not light, go to A-1, MIL INOPERATIVE in appropriate BASIC TESTING article.
2. Turn ignition off. Install scan tool and follow scan tool manufacturer's instructions to proceed with test. Turn ignition on. If scan tool displays PCM data, go to next step. If scan tool does not display PCM data, go to A-2, NO SCAN TOOL DATA in appropriate BASIC TESTING article.
3. Attempt to start engine. If engine starts and runs, go to next step. If engine does not start or starts and dies, go to NO START DIAGNOSIS (A-3) in appropriate BASIC TESTING article. Repair as necessary.
4. Using scan tool, observe DTC status on LAST TST FAIL function. If any DTC is stored, save freeze frame and failure record information using scan tool "Capture Info" feature. If a DTC is indicated as last test failed, diagnose DTC. If DTC is not indicated, go to next step.
5. Using scan tool, display DTC failure records. If a DTC failure record is stored, save freeze frame and failure record information using scan tool "Capture Info" feature. If a failure record is stored, diagnose DTC. If DTC(s) are not stored, check related circuit or component(s). See appropriate SYSTEM/COMPONENT TESTS article.

3.8L

1. Turn ignition on with engine off. Observe Malfunction Indicator Light (MIL). If MIL lights, go to next step. If MIL does not light, go to A-1, MIL INOPERATIVE in appropriate BASIC TESTING article.
2. Turn ignition off. Install scan tool and follow scan tool manufacturer's instructions to proceed with test. Turn ignition on. If scan tool displays PCM data, go to next step. If scan tool does not display PCM data, go to A-2, NO SCAN TOOL DATA in appropriate BASIC TESTING article.
3. Attempt to start engine. If engine starts and runs, go to next step. If engine does not start or starts and dies, go to NO START DIAGNOSIS (A-3) in appropriate BASIC TESTING article.
4. Using scan tool, observe DTC statuses; MIL REQUEST, FAIL THIS IGN, LAST TST FAIL and HISTORY. If any of these DTC status are present, refer to affected DTC to diagnose problem. If DTC(s) are not present, check related circuit or component(s). See appropriate SYSTEM/COMPONENT TESTS article.

P0502, VEHICLE SPEED SENSOR CIRCUIT (LOW INPUT)

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

Circuit Description

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 volts AC at 100 RPM to more than 100 volts AC at 8000 RPM. VSS resistance value is 1300-1950 ohms. DTC P0502 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. Transaxle is not in Park or Neutral.
2. DTCs P0107 and P0108 (MAP sensor), or P0122 and P0123 (throttle position) are not present.
3. Engine speed is more than 2900 RPM.
4. Throttle angle is more than 15 percent.
5. Output speed is less than 150 RPM for 2.5 seconds.
6. Engine torque is between 40-250 ft. lbs. (54-339 N.m) on 3.8L engine, or 40-150 ft. lbs (54-203 N.m) on all other engines.

DTC P0502 will be stored in PCM history. MIL will light at first failure signal. PCM will inhibit TCC and transaxle will default to 3rd gear.

Diagnostic Procedures

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 "Output Speed" 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 below.
3. Turn ignition off. Disconnect PCM Blue connector (C1). Connect voltmeter between VSS terminals at PCM Blue connector (C1). Rotate drive wheels and observe voltmeter display. If voltage is more than .5 volts, go to next step. If voltage is less than .5 volts, 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. Remove VSS from transaxle. Connect ohmmeter between VSS terminals. If resistance is 1300-1950 ohms, go to next step. If resistance is not 1300-1950 ohms, replace VSS, then go to step 8.
6. Install VSS into transaxle. Connect ohmmeter between VSS terminals at PCM Blue connector (C1). If resistance is less than 1300 ohms, go to next step. If resistance is more than 1950 ohms, check for open circuit between VSS and PCM. Repair as necessary, then go to step 8.
7. Check for VSS wires shorted together. Repair wires as necessary, then go to next step. If resistance is more than 1300 ohms, check for short to ground in circuits between VSS and PCM. Repair circuits as necessary, 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 "P0502". Test drive vehicle. If DTC P0502 is not present, repair is complete. If DTC P0502 is still present, repeat test.

Check for DTC P0705 (transaxle range switch). This DTC will affect transaxle upshifts and may cause a false DTC P0502. Check for Electromagnetic Interferences (EMI) induced on VSS circuits. Check for bent, backed out or broken terminals, or misaligned connectors. Ensure VSS is secured to transaxle case extension.

P0560, SYSTEM VOLTAGE MALFUNCTION

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

PCM monitors fused battery feed circuit for low or high system voltage.

Conditions For Setting DTC P0560

DTC will set under the following conditions

1. For low system voltage, engine speed is more than 800 RPM and system voltage is less than 10 volts for 2 seconds.
2. For high system voltage, transaxle fluid temperature is more than 32°F (0°C) and system voltage is more than 16 volts for 2 seconds.

DTC P0560 will be stored in PCM history. MIL will light at first failure signal. PCM will inhibit TCC and transaxle will default to 3rd gear.

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. Using a DVOM, measure and record battery voltage at battery. If voltage is more than 10.5 volts, go to next step. If voltage is less than 10.5 volts, diagnose battery condition and repair or replace as necessary.
3. Start engine. If charging light on instrument panel is on, diagnose charging system and repair as necessary. If charging light is off, select "Ignition Voltage" on scan tool. Increase engine speed to 1000-1500 RPM. Observe scan tool ignition voltage. If ignition voltage is 13-15 volts, go to next step. If ignition voltage is not 13-15 volts, diagnose charging system and repair as necessary.
4. Turn engine off. Disconnect PCM Blue connector (C1). Turn ignition switch to ON position. DO NOT start engine. Using a DVOM, check for battery voltage at battery feed terminal of PCM Blue connector (C1).
5. If difference between measured battery voltage in step 1 and voltage measured at PCM Blue connector (C1) is more than .5 volts, go to next step. If voltage is less than .5 volts, check for high resistance in battery feed circuit. Repair as necessary, then go to step 7.
6. Using a DVOM, check for ignition voltage at ignition feed terminal of PCM Blue connector (C1). If difference between measured battery voltage in step 1 and voltage measured at PCM Blue connector (C1) is more than .5 volts, check for high resistance in ignition feed circuit. Repair as necessary, then go to next step. If voltage is less than .5 volts, check PCM connector for bent, backed out or damaged connector pins. Repair as necessary, then go to next step. If connector pins are okay, replace PCM, then go to next step.
7. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0560". Start vehicle and warm to normal operating temperature. PCM must detect a system voltage of 10-18.9 volts. If DTC P0560 is not present, repair is complete. If DTC P0560 is still present, repeat test.

Charging battery with battery charger or jump starting vehicle could set DTC P0560. If DTC set when accessories are operated, check for poor system connections or excessive current draw. Check drive belt for wear or incorrect tension.

P0712, TRANS. FLUID TEMPERATURE (TFT) SENSOR CKT (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 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 detects a voltage input less than 200 mV on TFT sensor circuit.

Conditions For Setting DTC P0712

DTC will set under the following conditions

1. DTC P0560 (system voltage malfunction) is not present.
2. Ignition switch is in ON position.
3. PCM detects a reading of 298°F (198°C) or more for 10 seconds.

With ignition on for more than 5 minutes, PCM will use a default transaxle temperature of 203°F (95°C) for transaxle operation.

Diagnostic Procedure

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 "Transaxle Fluid Temperature" on scan tool. If TFT temperature is more than 293°F (145°C), go to next step. If TFT temperature is less than 293°F (145°C), see DIAGNOSTIC AIDS below.
3. Turn ignition off. Disconnect transaxle 7-pin harness connector. Turn ignition switch to ON position. DO NOT start engine. If TFT temperature is less than -33°F (-36°C), go to next step. If TFT temperature is more than -33°F (-36°C), check for short to ground in TFT signal circuit. Repair wire as necessary, then go to step 5.
4. Connect ohmmeter between transaxle case and TFT signal circuit at transaxle 7-pin harness connector (transaxle side of harness). If resistance is more than 1000 ohms, replace PCM, then go to next step. If resistance is less than 1000 ohms, check for short to ground in TFT signal circuit between transaxle 7-pin harness connector and TFT sensor. Repair circuit as necessary, then go to next step. If circuit is okay, replace TFT sensor, then go to next step.
5. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0712". Turn ignition switch to ON position for 15 seconds. If DTC P0712 is not present, repair is complete. If DTC P0712 is still present, repeat test.

Condition may be intermittent. Inspect transaxle and PCM connectors for bent terminals. Check engine and transaxle harness for short to ground. Check transaxle cooling system for possible blockage and/or restrictions.

P0713, TRANS. FLUID TEMPERATURE (TFT) SENSOR CKT (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 result in high signal voltage. TFT operating range is from -40° to 305°F (-40° to 151°C). DTC P0713 detects a voltage input more than 4.92 volts on TFT sensor circuit.

Conditions For Setting DTC P0713

DTC will set under the following conditions

1. DTC P0560 (system voltage malfunction) is not present.
2. Ignition switch is in ON position.
3. PCM detects a reading of -36°F (-36°C) or less (4.92 volts or more) for 7 minutes.

With ignition on for more than 5 minutes, PCM will use a default transaxle temperature of 203°F (95°C) for transaxle operation.

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 "Transaxle Fluid Temperature" on scan tool. If TFT temperature is less than -36°F (-36°C), go to next step. If TFT temperature is more than -36°F (-36°C), see DIAGNOSTIC AIDS below.
3. Turn ignition off. Disconnect transaxle 7-pin harness connector. Connect fused jumper wire between TFT signal circuit and sensor ground circuit of transaxle 7-pin harness connector (PCM side of harness). Turn ignition switch to ON position. DO NOT start engine. If TFT temperature is more than 293°F (145°C), go to step 5. If TFT temperature is less than 293°F (145°C), go to next step.
4. Connect TFT signal circuit to known good ground. If TFT temperature is more than 293°F (145°C), check for open in sensor ground circuit (PCM side of harness connector). Repair as necessary, then go to step 6. If circuit is okay, replace PCM, then go to step 6. If TFT temperature is less than 293°F (145°C), check for open in TFT signal circuit (PCM side of harness connector). Repair as necessary, then go to step 6. If circuit is okay, replace PCM, then go to step 6.
5. Check for open in TFT signal and sensor ground circuits (transaxle side of harness). Repair wire(s) as necessary, then go to next step. If circuits are okay, replace TFT sensor, then go to next step.
6. After repair is complete, select DTC on scan tool. Select "Clear Info" function. 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.

Condition may be intermittent. Inspect transaxle and PCM connectors for bent or backed out terminals.

P0719, 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 detects an open (stuck on) brake switch during acceleration.

Conditions For Setting DTC P0719

DTC will set under the following conditions

1. P0502 VSS signal is not present.
2. Vehicle speed is less than 5 MPH.
3. Vehicle takes more than 4 seconds to accelerate to 20 MPH.
4. Vehicle speed remains above 20 MPH for at least 6 seconds.
5. All conditions must occur 7 times with brake switch on for more than 15 minutes without PCM detecting voltage input of 2 seconds or longer.

For TCC operation, PCM will use throttle position inputs more than 6 percent and vehicle speed inputs more than 47 MPH for TCC apply.

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. If DTCs P1651 or P1652 (DTCs P1574 or P1575 on 3.8L) are also present, remove and inspect the appropriate fuse. Refer to the «WIRING DIAGRAMS»(/buick/riviera/viii-1994-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t60-e) . If fuse is open, check for short to ground in brake switch signal circuit 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 signal 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". Turn ignition switch to ON position. If DTC P0719 is not present, repair is complete. If DTC P0719 is still present, repeat test.

Check TCC brake switch for proper adjustment. Check PCM calibration for current update. Inspect brake switch and PCM connectors for bent, backed out or broken terminals.

P0724, 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 detects a closed (stuck off) brake switch during deceleration.

Conditions For Setting DTC P0724

DTC will set under the following conditions

1. P0502 (vehicle speed sensor) is not present.
2. Vehicle speed is more than 20 MPH for at least 6 seconds.
3. Then vehicle takes more than 4 seconds to decrease speed from 20 MPH to 5 MPH.
4. Then vehicle speed is less than 5 MPH.
5. All conditions must occur 7 times with brake switch off continuously without PCM detecting voltage input of 2 seconds or longer.

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 "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 signal 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. Select "Specific DTC" and enter DTC "P0724". Turn ignition switch to ON position for 15 seconds. If DTC P0724 is not present, repair is complete. If DTC P0724 is still present, repeat test.

Check TCC brake switch for proper adjustment. Check PCM calibration for current update. Inspect brake switch and PCM connectors for bent, backed out or broken terminals.

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) solenoid controls hydraulic fluid for TCC apply and release. DTC P0742 will set when TCC is commanded off and PCM detects 3 occurrence's of TCC slip from -20 RPM to 30 RPM for 8 seconds.

Conditions For Setting DTC P0742

DTC will set under the following conditions

1. DTCs P0122 or P0123 (throttle position) or DTC P0502 (vehicle speed sensor) are not present.
2. DTCs P1860 (TCC PWM solenoid) or DTC P1864 (TCC enable solenoid) are not present.
3. Engine speed is more than 500 RPM for 5 seconds.
4. MAP is 0-15 psi (0-105 kPa).
5. Vehicle is not in fuel shut off mode.
6. TCC is commanded off.
7. Commanded gear is not 1st gear.
8. Transaxle gear indicates 2nd, 3rd or 4th.
9. Throttle angle is more than 18 percent.
10. Engine torque is 80-170 ft. lbs. (108-230 N.m).
11. TCC slip speed is from -20 RPM to 30 RPM 3 times for 5 seconds.

MIL will light after 2 consecutive trips with failure reported.

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. Using scan tool, check TCC slip speed. If slip speed is from -20 RPM to 30 RPM, see DIAGNOSTIC AIDS below. If slip speed is not from -20 RPM to 30 RPM, inspect and repair TCC enable solenoid or TCC apply valve. Components may be stuck on due to sediment. Refer to «AUTO TRANS OVERHAUL - 4T60-E»(/buick/riviera/viii-1994-1999/remont/automatic-trans/#automatic-transaxle-overhaul-testing-4t60-e) article.
3. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0742". Test drive vehicle and ensure TCC applies. If DTC P0742 is not present, repair is complete. If DTC P0742 is still present, repeat test.

Check for DTC P0705 (transaxle range switch). This DTC will affect transaxle operation and may cause a false DTC P0742. Inspect transaxle fluid for sediment or debris.

P0751, 1-2 SHIFT SOLENOID ("A") PERFORMANCE PROBLEM

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 shift solenoid "A" problem by monitoring commanded gear and speed ratio. DTC P0751 will set if PCM detects a 2-3 or 1-4 shift pattern only.

Conditions For Setting DTC P0751

DTC will set under the following conditions

1. DTCs P0122 or P0123 (throttle position) or DTC P0502 (vehicle speed sensor) are not present.
2. DTC P0742 (TCC stuck on) is not present.
3. DTCs P0753 (shift solenoid "A" electrical problem) or DTC P0758 (shift solenoid "B" electrical problem) are not present.
4. DTCs P1860 (TCC PWM solenoid) or DTC P1864 (TCC enable solenoid) are not present.
5. Engine speed is more than 500 RPM for 5 seconds.
6. Vehicle speed is more than 5 MPH.
7. Vehicle is not in fuel shut off mode.
8. Traction control is not active (if equipped).
9. Transaxle temperature is 68-266°F (20-130°C).
10. Transaxle range switch indicates D4.

DTC P0751 will be stored in PCM history. MIL will light after second consecutive ignition cycles without failure reported. PCM will inhibit downshifts to 2nd gear if vehicle speed is more than 30 MPH. DTC has 5 different failure criteria. These criteria are as follows

Criteria No. 1

Throttle position sensor is 18-45 percent and constant by 5 percent. 1-2 shift is commanded. Vehicle speed is 5-45 MPH. When 2nd gear is commanded and within 2.5 seconds, engine RPM is more than 110 RPM from engine RPM of commanded 1st gear.

Criteria No. 2

Throttle position sensor is 18-45 percent and constant by 5 percent. 2-3 shift is commanded. Vehicle speed is 25-55 MPH. When 3rd gear is commanded and within 2.5 seconds, engine RPM is less than 150 RPM from engine RPM of commanded 2nd gear.

Criteria No. 3

Throttle position sensor is 18-45 percent and constant by 3 percent. 3-4 shift is commanded. Vehicle speed is 35-80 MPH. When 4th gear is commanded and within 2.5 seconds, engine RPM is more than 5 RPM from engine RPM of commanded 3rd gear.

Criteria No. 4

Throttle position sensor is 7-37 percent. 4th gear is commanded and TCC is on. Speed ratio is between 40-42. TCC slip is 500-1000 RPM for more than 4 seconds.

Criteria No. 5

Throttle position sensor is 7-37 percent. 4th gear is commanded and TCC is on. Speed ratio is between 28-30. TCC slip is between -20 RPM and 25 RPM for more than 4 seconds.

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. If DTC P0751 is present, replace shift solenoid "A". After replacement is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0751". Test drive vehicle. Ensure transaxle upshifts and downshifts correctly. If DTC P0751 is not present, repair is complete. If DTC P0751 is still present, see appropriate «COMPONENT TESTS»(/buick/riviera/viii-1994-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t60-e__component-tests-with-test-box) under ELECTRONIC TESTING.

Check for DTC P0705 (transaxle range switch). This DTC will affect transaxle upshifts and may cause a false DTC P0751. Inspect transaxle fluid for sediment or debris.

P0753, 1-2 SHIFT SOLENOID ("A") ELECTRICAL PROBLEM

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

Shift solenoid "A" is used to control transaxle fluid to 1-2 shift valve. 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 shift solenoid "A" is commanded on, PCM will detect low voltage. When shift solenoid "A" is commanded off, PCM will detect high voltage. DTC P0753 will set if voltage limits DO NOT meet calibration at anytime.

Conditions For Setting DTC P0753

DTC will set under the following conditions

1. DTC P0560 (system voltage malfunction) is not present.
2. Engine speed is more than 500 RPM for 5 seconds.
3. Vehicle is not in fuel shut off mode.

DTC P0753 will be stored in PCM history. MIL will light at first failure signal. PCM will inhibit downshifts to 2nd gear if vehicle speed is more than 30 MPH.

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, P1860 and P1864 are present, go to next step. If DTCs P0758, P1860 and P1864 are not present, go to step 3.
2. Remove and inspect appropriate fuse. See «WIRING DIAGRAMS»(/buick/riviera/viii-1994-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t60-e) . Replace fuse if necessary. If fuse is blown, check for short to ground in circuit between fuse and transaxle 7-pin harness connector. If fuse is okay, check for open in circuit between fuse and transaxle 7-pin harness connector. After repair is complete, go to step 8.
3. Turn ignition off. Disconnect transaxle 7-pin harness connector. Install Transaxle Jumper (J-38835) to PCM side of transaxle 7-pin harness connector. Connect a test light between fuse terminal and shift solenoid "A" control terminal at jumper. 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 shift solenoid "A" control circuit between transaxle 7-pin harness connector and PCM. Repair circuit as necessary, then go to step 8. If circuit is okay, replace PCM, then go to step 8.
4. Select "A/T Outputs", Shift Solenoid "A" on scan tool. 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 short to ground in shift solenoid "A" control circuit between transaxle 7-pin harness 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 shift solenoid "A" control circuit between transaxle 7-pin harness 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. Disconnect transaxle jumper from PCM side of transaxle 7-pin harness connector. Connect jumper to transaxle side of 7-pin harness connector. Connect an ohmmeter between fuse terminal and shift solenoid "A" terminal at jumper. If resistance is 20-40 ohms, replace PCM, then go to step 8.
6. If resistance is less than 100 ohms, go to next step. If resistance is more than 100 ohms, check for open in shift solenoid "A" power and ground circuits between transaxle 7-pin harness connector and solenoid. Repair circuit(s) as necessary, then go to step 8. If circuits are okay, replace shift solenoid "A", then go to step 8.
7. Connect ohmmeter between ground and shift solenoid "A" terminal at jumper. If resistance is less than 100 ohms, check for short to ground in circuit between transaxle 7-pin harness connector and shift solenoid "A". Repair circuit as necessary, then go to next step. If circuit is okay, replace shift solenoid "A", 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 "P0753". Start engine and allow to run for 15 seconds. If DTC P0753 is not present, repair is complete. If DTC P0753 is still present, repeat test.

Inspect PCM, transaxle and shift solenoid "A" connectors for bent, broken or backed out terminals.

P0756, 2-3 SHIFT SOLENOID ("B") PERFORMANCE PROBLEM

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 shift solenoid "B" problem by monitoring commanded gear and speed ratio. DTC P0756 will set if PCM detects a gear other than 1st gear when 1st gear is commanded, or 1st gear when 4th gear is commanded.

Conditions For Setting DTC P0756

DTC will set under the following conditions

1. DTCs P0122 or P0123 (throttle position) or DTC P0502 (vehicle speed sensor) are not present.
2. DTCs P0712, P0713 or P1812 (transaxle fluid temperature) are not present.
3. Engine speed is more than 500 RPM for 5 seconds.
4. Vehicle speed is more than 20 MPH.
5. Vehicle is not in fuel shut off mode.
6. Traction control is not active.
7. Transaxle temperature is more than 68°F (20°C).
8. Transaxle range switch indicates D1, D2, D3 or D4.

DTC P0756 will be stored in PCM history. MIL will light after 2 consecutive trips with a failure reported. DTC has 2 different failure criteria. These criteria are as follows

Throttle position sensor is more than 37 percent. PCM is commanding 1st gear and speed ratio is less than 105 for 2.5 seconds. (shift valve stuck in off position).

Throttle position sensor is more than 18 percent. PCM is commanding 4th gear and speed ratio is more than 100 for 2 seconds (shift valve stuck in on position).

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. If DTC P0756 is present, replace shift solenoid "B". After replacement is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0756". Test drive vehicle. Ensure transaxle upshifts and downshifts correctly. If DTC P0756 is not present, repair is complete. If DTC P0756 is still present, see appropriate «COMPONENT TESTS»(/buick/riviera/viii-1994-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t60-e__component-tests-with-test-box) under ELECTRONIC TESTING.

Check for DTC P0705 (transaxle range switch). This DTC will affect transaxle upshifts and may cause a false DTC P0756. Inspect transaxle fluid for sediment or debris.

P0758, 2-3 SHIFT SOLENOID ("B") ELECTRICAL PROBLEM

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

Shift solenoid "B" is used to control transaxle fluid to 2-3 shift valve. 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 shift solenoid "B" is commanded on, PCM will detect low voltage. When shift solenoid "B" is commanded off, PCM will detect high voltage. DTC P0758 will set if voltage limits do not meet calibration at anytime.

Conditions For Setting DTC P0758

DTC will set under the following conditions

1. DTC P0560 (system voltage malfunction) is not present.
2. Engine speed is more than 500 RPM for 5 seconds.
3. Vehicle is not in fuel shut off mode.

DTC P0758 will be stored in PCM history. MIL will light at first failure signal. PCM will inhibit TCC and transaxle will default to 3rd gear.

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, P1860 and P1864 are present, go to next step. If DTCs P0753, P1860 and P1864 are not present, go to step 3.
2. Remove and inspect appropriate fuse. See «WIRING DIAGRAMS»(/buick/riviera/viii-1994-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t60-e) . Replace fuse if necessary. If fuse is blown, check for short to ground in circuit between fuse and transaxle 7-pin harness connector. If fuse is okay, check for open in circuit between fuse and transaxle 7-pin harness connector. After repair is complete, go to step 8.
3. Turn ignition off. Disconnect transaxle 7-pin harness connector. Install Transaxle Jumper (J-38835) to PCM side of transaxle 7-pin harness connector. Connect a test light between fuse terminal and shift solenoid "B" control terminal at jumper. 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 shift solenoid "B" control circuit between transaxle 7-pin harness connector and PCM. Repair circuit as necessary, then go to step 8. If circuit is okay, replace PCM, then go to step 8.
4. Select "A/T Outputs", Shift Solenoid "B" on scan tool. 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 short to ground in shift solenoid "B" control circuit between transaxle 7-pin harness 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 shift solenoid "B" control circuit between transaxle 7-pin harness 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. Disconnect transaxle jumper from PCM side of transaxle 7-pin harness connector. Connect jumper to transaxle side of 7-pin harness connector. Connect an ohmmeter between fuse terminal and shift solenoid "B" terminal at jumper. If resistance is 20-40 ohms, replace PCM, then go to step 8.
6. If resistance is less than 100 ohms, go to next step. If resistance is more than 100 ohms, check for open in shift solenoid "B" power and ground circuits between transaxle 7-pin harness connector and solenoid. Repair circuit(s) as necessary, then go to step 8. If circuits are okay, replace shift solenoid "B", then go to step 8.
7. Connect ohmmeter between ground and shift solenoid "B" terminal at jumper. If resistance is less than 100 ohms, check for short to ground in circuit between transaxle 7-pin harness connector and shift solenoid "B". Repair circuit as necessary, then go to next step. If resistance is more than 100 ohms, replace shift solenoid "B", 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 "P0758". Start engine and allow to run for 15 seconds. If DTC P0758 is not present, repair is complete. If DTC P0758 is still present, repeat test.

Inspect PCM, transaxle and shift solenoid "B" connectors for bent, broken or backed out terminals.

P1812, 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. TFT range is from -40 to 305°F (-40 to 151°C). DTC 1812 will set if PCM detects a high transaxle temperature for an extended period of time on TFT sensor circuit.

Conditions For Setting DTC P1812

DTC will set under the following conditions

1. DTCs P0712 or P0713 (transaxle fluid temperature) are not present.
2. Transaxle fluid temperature is more than 266°F (130°C) for more than 7 minutes.

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. Read transaxle fluid temperature. If fluid temperature is 266°F (130°C) or more, inspect for engine overheating (thermostat), vehicle overloading, transaxle fluid contaminated with anti-freeze, transaxle filter clogged or not seated properly, low line pressure (cooler lines clogged or restricted) or restricted radiator. Repair or replace components as necessary, then go to next step.
3. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P1812". Turn ignition on for more than 5 seconds. If DTC P1812 is not present, repair is complete. If DTC P1812 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.

P1860, PWM SOLENOID ELECTRICAL PROBLEM

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 will set if voltage limits do not meet calibration at anytime.

Conditions For Setting DTC P1860

DTC will set under the following conditions

1. DTC P0560 (system voltage malfunction) is not present.
2. Engine speed is more than 500 RPM for 5 seconds.
3. TCC duty cycle is less than 10 percent or more than 90 percent.
4. Vehicle is not in fuel shut off mode.

DTC P1860 will be stored in PCM history. MIL will light at first failure signal. PCM will inhibit TCC. PCM will inhibit 4th gear if transaxle is in hot mode.

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, P0758 and P1864 are present, go to next step. If DTCs P0753, P0758 and P1864 are not present, go to step 3.
2. Remove and inspect appropriate fuse. See «WIRING DIAGRAMS»(/buick/riviera/viii-1994-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t60-e) . Replace fuse if necessary. If fuse is blown, check for short to ground in circuit between fuse and transaxle 7-pin harness connector. If fuse is okay, check for open in circuit between fuse and transaxle 7-pin harness connector. After repair is complete, go to step 8.
3. Turn ignition off. Disconnect transaxle 7-pin harness connector. Install Transaxle Jumper (J-38835) to PCM side of transaxle 7-pin harness connector. Connect a test light between fuse terminal and PWM solenoid control terminal at jumper. Turn ignition switch to ON position. DO NOT start engine. If test light is on, go to next step. If test light is off, check for open in PWM solenoid control circuit between transaxle 7-pin harness connector and PCM. Repair circuit as necessary, then go to step 8. If circuit is okay, replace PCM, then go to step 8. NOTE: In the following step, if PWM solenoid is on, test light will be bright. If PWM solenoid is off, test light will pulsate.
4. Select "A/T Outputs", TCC PWM Solenoid on scan tool. 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 short to ground in PWM solenoid control circuit between transaxle 7-pin harness 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 PWM solenoid control circuit between transaxle 7-pin harness 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. Disconnect transaxle jumper for PCM side of transaxle 7-pin harness connector. Connect jumper to transaxle side of 7-pin harness connector. Connect an ohmmeter between fuse terminal and PWM solenoid terminal at jumper. If resistance is 10-15 ohms, replace PCM, then go to step 8.
6. If resistance is less than 100 ohms, go to next step. If resistance is more than 100 ohms, check for open in PWM solenoid power and ground circuits between transaxle 7-pin harness connector and solenoid. Repair circuit(s) as necessary, then go to step 8. If circuits are okay, replace TCC PWM solenoid, then go to step 8.
7. Connect ohmmeter between ground and PWM solenoid terminal at jumper. If resistance is less than 100 ohms, check for short to ground in circuit between transaxle 7-pin harness connector and PWM solenoid. Repair circuit as necessary, then go to next step. If resistance is more than 100 ohms, replace TCC PWM solenoid, 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 "P1860". Road test vehicle and ensure TCC applies. If DTC P1860 is not present, repair is complete. If DTC P1860 is still present, repeat test.

Inspect PCM, transaxle and PWM solenoid connectors for bent, broken or backed out terminals. Ensure transaxle fluid level is correct.

P1864, TCC SOLENOID ELECTRICAL PROBLEM

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

Torque Converter Clutch (TCC) enable solenoid is used in conjunction with TCC PWM solenoid to control fluid acting on TCC converter clutch valve, to control TCC apply and release. PCM monitors throttle position, vehicle speed, and other inputs to determine when to energize TCC solenoid. Ignition voltage is supplied directly to TCC solenoid. PCM controls solenoid by providing ground path. When solenoid is commanded off, PCM will detect high voltage. When solenoid is commanded on, PCM will detect low voltage. DTC P1864 will set if voltage limits do not meet calibration at anytime.

Conditions For Setting DTC P1864

DTC will set under the following conditions

1. DTC P0560 (system voltage malfunction) is not present.
2. Engine speed is more than 500 RPM for 5 seconds.
3. Vehicle is not in fuel shut off mode.

DTC P1864 will be stored in PCM history. MIL will light at first failure signal. PCM will inhibit TCC. PCM will inhibit 4th gear if transaxle is in hot mode.

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, P0758 and P1864 are present, go to next step. If DTCs P0753, P0758 and P1864 are not present, go to step 3.
2. Remove and inspect appropriate fuse. See «WIRING DIAGRAMS»(/buick/riviera/viii-1994-1999/remont/automatic-trans/#automatic-transaxle-diagnosis-4t60-e) . Replace fuse if necessary. If fuse is blown, check for short to ground in circuit between fuse and transaxle 7-pin harness connector. If fuse is okay, check for open in circuit between fuse and transaxle 7-pin harness connector. After repair is complete, go to step 8.
3. Turn ignition off. Disconnect transaxle 7-pin harness connector. Install Transaxle Jumper (J-38835) to PCM side of transaxle 7-pin harness connector. Connect a test light between fuse terminal and TCC solenoid control terminal at jumper. 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 TCC solenoid control circuit between transaxle 7-pin harness connector and PCM. Repair circuit as necessary, then go to step 8. If circuit is okay, replace PCM, then go to step 8.
4. Select "A/T Outputs", TCC Solenoid on scan tool. 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 open in TCC solenoid control circuit between transaxle 7-pin harness 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 TCC solenoid control circuit between transaxle 7-pin harness 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. Disconnect transaxle jumper for PCM side of transaxle 7-pin harness connector. Connect jumper to transaxle side of 7-pin harness connector. Connect an ohmmeter between fuse terminal and TCC solenoid terminal at jumper. If resistance is 20-40 ohms, replace PCM, then go to step 8.
6. If resistance is less than 100 ohms, go to next step. If resistance is more than 100 ohms, check for open in TCC solenoid power and ground circuits between transaxle 7-pin harness connector and solenoid. Repair circuit(s) as necessary, then go to step 8. If circuits are okay, replace TCC solenoid, then go to step 8.
7. Connect ohmmeter between ground and TCC solenoid terminal at jumper. If resistance is less than 100 ohms, check for short to ground in circuit between transaxle 7-pin harness connector and TCC solenoid. Repair circuit as necessary, then go to next step. If resistance is more than 100 ohms, replace TCC solenoid, 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 "P1864". Road test vehicle and ensure TCC applies. If DTC P1864 is not present, repair is complete. If DTC P1864 is still present, repeat test.

Inspect transaxle and PCM connectors for bent, broken or backed out terminals.

P1870, TRANSAXLE COMPONENT SLIPPING

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 monitors Torque Converter Clutch (TCC) slip speed by calculating difference between engine speed and transaxle output speed. DTC P1870 detects excessive TCC slip when TCC is engaged.

Conditions For Setting DTC P1870

DTC will set under the following conditions

1. DTCs P0122 and P0123 (throttle position), or P0502 (vehicle speed sensor) are not present.
2. DTCs P0751 and P0753 (shift solenoid "A") are not present.
3. DTCs P0756 and P0758 (shift solenoid "B") are not present.
4. DTC P1860 (TCC PWM solenoid) is not present.
5. DTC P1864 (TCC solenoid) is not present.
6. Engine speed is more than 500 RPM for more than 5 seconds.
7. Vehicle is not in fuel shut off mode.
8. Throttle position is 9.5-35 percent.
9. Transaxle is in D4.
10. Transaxle is not in 1st gear.
11. Engine torque is 50-170 ft. lbs. (68-230 N.m).
12. Transaxle temperature is 68-266°F (20-130°C).
13. TCC is commanded on and at maximum apply for more than 4 seconds.
14. MAP is 0-15 psi (0-105 kPa).
15. TCC slip is more than 200 RPM for more than 4 seconds.
16. All conditions must occur 3 times with TCC commanded off between each occurrence.

DTC P1870 will be stored in PCM history. MIL will light at first failure signal. PCM will inhibit TCC. PCM will inhibit 4th gear if transaxle is in hot mode.

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 "TCC slip speed" on scan tool. With gear selector in D4 position, drive vehicle and ensure TCC is engaged. If TCC slip speed is more than 200 RPM, go to next step. If TCC slip speed is not more than 200 RPM, see DIAGNOSTIC AIDS below.
3. Inspect and replace vacuum modulator as necessary. See HYDRAULIC PRESSURE TESTS in «AUTO TRANS OVERHAUL - 4T60-E»(/buick/riviera/viii-1994-1999/remont/automatic-trans/#automatic-transaxle-overhaul-testing-4t60-e) article. If modulator is okay, inspect mechanical components and repair or replace as necessary.
4. Check for stuck TCC solenoid or TCC PWM solenoid check ball. Check for stuck converter clutch or regulator valve. Check for cut or missing turbine shaft "O" ring seal. Check for stuck torque converter pressure plate. Check for worn or glazed fiber material in torque converter. Check for stuck 3-4 shift valve.
5. Check for burned or damaged 2nd, 3rd or 4th clutch composition plates. Check for cut or rolled input shaft, 2nd, 3rd or 4th clutch piston seals. Check for rolled or twisted driven sprocket support ring, or worn sleeve in 2nd clutch housing.
6. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P1870". Drive vehicle and ensure transaxle shifts into all 4 gears and TCC applies. If DTC P1870 is not present, repair is complete. If DTC P1870 is still present, repeat test.

Check for DTC P0705 (transaxle range switch). This DTC will affect transaxle upshifts and may cause a false DTC P1870. Verify final drive ratio is correct for specific vehicle. Ensure transaxle shifts through all 4 gear positions when gear selector lever is in D4 position.

1996 "A" Body - 3.1L (Century & Ciera) Wiring Diagram. Scheme 64

1996 "C" & "H" Body - 3.8L (Bonneville, Eighty-Eight, LeSabre, Ninety-Eight & Park Avenue) Wiring Diagram. Scheme 65

1996 "G" Body - 3.8L (Riviera) Wiring Diagram. Scheme 66

1996 "L" Body - 3.1L (Beretta & Corsica) Wiring Diagram. Scheme 67

1996 "N" Body - 2.4L (Achieva, Grand Am & Skylark) Wiring Diagram. Scheme 68

1996 "N" Body - 3.1L (Achieva, Grand Am & Skylark) Wiring Diagram. Scheme 69

1996 "U" Body - 3.4L (Lumina APV, Silhouette & Trans Sport) Wiring Diagram. Scheme 70

1996 "W" Body - 3.1L & 3.4L (Cutlass Supreme, Grand Prix, Lumina, Monte Carlo & Regal) Wiring Diagram. Scheme 71

1996 "W" Body - 3.8L (Regal) Wiring Diagram. Scheme 72

See also:
• AUTO TRANS OVERHAUL - 4T60-E
• TESTS W/O CODES
• CLUTCH & BAND APPLICATION CHART (4T60-E)
• COMPONENT TESTS
• CLEARING TROUBLE CODES
• P0502
• P0560
• P0712
• P0713
• P0719
• P0724
• P0742
• P0751
• P0753
• P0756
• P0758
• P1812
• P1860
• P1864
• P1870
• RETRIEVING CODES