Diagnosis - 4t60-e Buick Century V

APPLICATION

THM 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). The 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 the 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) under ELECTRONIC TESTING.

PCM

On Cutlass Supreme, Grand Prix, Lumina and Regal, PCM is located at right side of engine compartment. On other models, the PCM is located under right kick panel. PCM controls ignition, fuel and emission devices related to the engine and transaxle upshifts and downshifts.

The PCM receives electronic signals from sensors and switches. These signals help the PCM determine when to operate various relays and solenoids related to engine and transaxle control.

SENSORS & SWITCHES

The PCM controls upshifts and downshifts based on coolant temperature (or transaxle temperature), throttle position, PRNDL or gear switch position, vehicle speed sensor and brake pedal switch. The system includes several other switches and sensors which are used for engine control. These are covered in the ENGINE PERFORMANCE section.

SOLENOIDS

Transaxle is shifted up or down by 2 electric solenoids. Both solenoids are located on the valve body. Ignition power is supplied to each solenoid by the cooling fan fuse (most models).

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

SELF-DIAGNOSTICS

PCM constantly monitors all electrical circuits. If PCM detects circuit problems or sensors out of range, it will record trouble codes. If problem continues for a predetermined time, CHECK ENGINE or SERVICE ENGINE SOON light will glow.

If the CHECK ENGINE or SERVICE ENGINE SOON light is on all the time, trouble code(s) are currently being detected. If the CHECK ENGINE or SERVICE ENGINE SOON light is off, but PCM had detected a circuit or sensor problem, trouble code(s) will be stored in computer memory.

Stored trouble codes may be retrieved from PCM memory. Depending on the vehicle, several methods may be used. The most basic method (non-scan) uses a jumper wire and watching the CHECK ENGINE or SERVICE ENGINE SOON light flash a series of codes.

Other methods include using a factory recommended Tech 1 scan tool or aftermarket scan tool.

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

CLUTCH & BAND APPLICATIONS

CLUTCH & BAND APPLICATION CHART (4T60-E)

ELECTRONIC SELF-DIAGNOSTICS

Note. To test electronic control of transaxle solenoids without using self-diagnostics or if self-diagnostics will not work, go to appropriate COMPONENT TESTS under ELECTRONIC TESTING . After repairs are made, trouble codes should be erased from computer memory. See CLEARING TROUBLE CODES under ELECTRONIC SELF-DIAGNOSIS.

Scheme 109

1. Turn ignition on. DO NOT start engine. CHECK ENGINE or SERVICE ENGINE SOON light should glow. Locate Assembly Line Data Link (ALDL) connector attached to control module wiring harness. Most ALDL connectors are located under dash on driver's side of vehicle. Turn ignition on with engine not running. Insert jumper wire from terminal "B" (diagnostic test terminal) to terminal "A" (ground) of ALDL connector. (Scheme 109) NOTE: Inserting jumper wire into test and ground terminals of ALDL connector with engine running will cause fuel injected vehicles to enter field service mode. The CHECK ENGINE or SERVICE ENGINE SOON light will not indicate codes if this is done. NOTE: Code 12 should always exist when ALDL is grounded with key on and engine not running.
2. CHECK ENGINE or SERVICE ENGINE SOON light should begin to flash codes. Each code will be repeated 3 times. For example, FLASH, FLASH, pause, FLASH, longer pause, identifies Code 21. The first series of flashes is the first digit of trouble code. The second series of flashes is the second digit of trouble code.
3. Trouble codes are displayed starting with lowest numbered code. Each code is displayed 3 times. Codes will continue to repeat as long as ALDL test terminal is grounded.
4. If codes are not flashed, or CHECK ENGINE or SERVICE ENGINE SOON light does not glow, self-diagnostics will not work. See DIAGNOSTIC CIRCUIT CHECK in BASIC TESTING article in the ENGINE PERFORMANCE section. To exit diagnostic mode, turn ignition off and remove jumper wire from ALDL connector.

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 (WITH SCAN TOOL)

Note. Plugging scan tester into the ALDL enables user to read trouble codes and check voltages in the system on the serial data line.

The scan tester is a specialized tester which, when plugged into ALDL, can be used to diagnose on-board computer control systems by providing instant access to circuit voltage information, eliminating the need to crawl under dash or hood to backprobe sensors and connectors.

Scan testers 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.

Note. Code 12 should always exist when ALDL is grounded with key on and engine not running, but may not be indicated by all makes of scan tools. On 1994 models, Code 12 will not be present on vehicles which require the use of a scan tester to obtain codes.

If trouble codes are not present, this is not necessarily an indication that there is not a problem. 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 the 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 harnesses and connections (key on, engine off) while observing scan tool.

Note. If erroneous voltage signals are suspected, it will be necessary to verify tester information using a digital voltmeter and wiring schematic. If non-existent codes are displayed, turn ignition off, remove tester, turn ignition on and ground ALDL test terminal "B". (Scheme 109) The same codes flashed by CHECK ENGINE or SERVICE ENGINE SOON light should be indicated by scan tool.

TROUBLE CODE DEFINITION

PCM TROUBLE CODE DEFINITION (2.3L)

PCM TROUBLE CODE DEFINITION (3.1L - EXCEPT CENTURY & CIERA)

PCM TROUBLE CODE DEFINITION (3.1L CENTURY & CIERA, 3.4L & 3.8L)

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 charts will not usually help analyze intermittent codes. To determine hard codes and intermittent codes, proceed as follows

1. Manually enter diagnostic mode. See RETRIEVING CODES (WITHOUT SCAN TOOL) Read and record all stored trouble codes. Exit diagnostic mode and clear trouble codes. See CLEARING TROUBLE CODES.
2. Apply parking brake and place transaxle in Neutral or Park. Block drive wheels and start engine. CHECK ENGINE or SERVICE ENGINE SOON light should go out. Run warm engine at specified curb idle for 2 minutes and note CHECK ENGINE or SERVICE ENGINE SOON light.
3. If CHECK ENGINE or SERVICE ENGINE SOON light comes on, MANUALLY enter diagnostic mode. Read and record trouble codes. This will reveal hard failure codes. Trouble codes may require a road test to reset hard failure after clearing trouble codes.
4. If CHECK ENGINE or SERVICE ENGINE SOON light does not come on, all stored trouble codes were intermittent failures.

CLEARING TROUBLE CODES

Turn ignition switch to ON position, and ground diagnostic test terminal "B" at ALDL connector. (Scheme 109) Turn ignition switch to OFF position, and remove control module fuse from fuse block for 10 seconds. Replace fuse. Remove diagnostic terminal ground lead. If fuse cannot be located, disconnect pigtail at battery. After power to PCM is removed, poor driveability may occur until control module "relearns" operating parameters.

Diagnostic Charts

Following charts are typical flow charts and testing information. For electrical wiring diagrams, see WIRING DIAGRAMS . For more engine diagnostic information, see appropriate article in the ENGINE PERFORMANCE section.

Diagnostic Aids

Diagnostic aids (located in many trouble code charts) are additional tips used to help diagnose trouble codes when circuit checks do not find a problem.

Note. For the purpose of the diagnostic charts, either Electronic Control Module (ECM) or Powertrain Control Module (PCM) may be used to describe the vehicle's computer.

CODE 14/P0118, COOLANT TEMP. SENSOR SIGNAL VOLTAGE LOW

Note. This chart applies when engine cooling system is functioning properly (not overheating). Test numbers refer to test numbers on diagnostic chart.

1. Code 14/P0118 indicates the control module has seen low coolant sensor voltage signal (high temperature) at control module terminal for a precalibrated period of time. This checks if conditions for Code 14/P0118 still exist.
2. This tests for grounded sensor signal line between control module and coolant sensor.

After the engine is started, temperature should rise steadily to about 190°F (88°C), then stabilize when thermostat opens. At normal operating temperature, signal voltage at control module terminal should be 1.5-2.0 volts. Check sensor for shifted calibration by using sensor TEMPERATURE-TO-RESISTANCE VALUES table. When Code 14/P0118 is set, control module will turn on electric cooling fan(s), if equipped.

Scheme 110

Scheme 111

CODE 14/P0118 PCM TERMINAL & CIRCUIT WIRING IDENTIFICATION

TEMPERATURE-TO-RESISTANCE VALUES (1)

CODE 15/P0117, COOLANT TEMP. SENSOR SIGNAL VOLTAGE HIGH

Note. Test numbers refer to test numbers on diagnostic chart.

1. Code 15/P0117 indicates control module has seen high resistance in coolant sensor circuit. This could be due to high resistance (cold temperature) or high voltage at coolant sensor terminal at control module for a precalibrated period of time. This checks if conditions for Code 15/P0117 still exist.
2. This test simulates conditions for a Code 14/P0118. If control module recognizes the low voltage signal, scan tester will display greater than 130°C. This indicates the control module and wiring are not at fault.
3. This test determines if coolant sensor ground or signal circuit is open.

After the engine is started, temperature should rise steadily to about 190°F (88°C), then stabilize when thermostat opens. At normal operating temperature, voltage at control module sensor signal line should be 1.5-2.0 volts. Check sensor for shifted calibration by using sensor TEMPERATURE-TO-RESISTANCE VALUES table. When Code 14/P0118 is set, control module will turn on electric cooling fan(s), if equipped.

Scheme 112

CODE 15/P0117 PCM TERMINAL & CIRCUIT WIRING IDENTIFICATION

CODE 21/P0123, THROTTLE POSITION SENSOR SIGNAL VOLTAGE HIGH

Note. Test numbers refer to test numbers on diagnostic chart.

1. This test checks if code is the result of a hard failure or an intermittent condition.
2. This test simulates conditions for a Code 22/P0122. If control module recognizes the change of state, the control module and wiring are okay.
3. This step isolates a faulty sensor, control module or open sensor ground circuit. If sensor ground is shared by another sensor, there may be an accompanying code related to that sensor.

A scan tester displays throttle position in volts. Closed throttle voltage should be low. Voltage should increase gradually to about 4.5 volts at a steady rate, as throttle angle is increased.

Scheme 113

Scheme 114

CODE 21/P0123 PCM TERMINAL & CIRCUIT WIRING IDENTIFICATION

CODE 22/P0122, THROTTLE POSITION SENSOR SIGNAL VOLTAGE LOW

Note. Test numbers refer to test numbers on diagnostic chart.

1. This test checks if code is the result of a hard failure or an intermittent condition.
2. This test simulates conditions for a Code 21/P0123. If control module recognizes the change of state, the control module and wiring are okay.
3. This simulates a high signal voltage to check for an open in the TPS signal line to control module. scan tester should recognize this signal and display high TPS voltage.

A scan tester displays throttle position in volts. Closed throttle voltage should be low. Voltage should increase gradually to about 4.5 volts at a steady rate, as throttle angle is increased.

Scheme 115

CODE 22/P0122 PCM TERMINAL & CIRCUIT WIRING IDENTIFICATION

CODE 24, VEHICLE SPEED SENSOR 2.3L, 3.1L "L", "N" & "W" BODIES/3.4L & 3.8L "W" BODIES

Speed sensor, which is a Permanent Magnet (PM) generator, provides control module with vehicle speed information. PM generator, mounted in transaxle, produces a pulsing AC voltage signal whenever vehicle speed is greater than 3 MPH. Voltage level and pulses increase with vehicle speed. Control module converts pulsing voltage to MPH, which is used by control module to calculate vehicle adjustments.

Note. Test numbers refer to numbers on diagnostic chart.

1. Code 24 sets when MPH reads zero, transaxle is not in Park or Neutral, engine speed indicates vehicle is in a cruise mode (1200-4400) RPM, TPS indicates closed throttle and MAP sensor senses high manifold vacuum. All of these conditions must be met for 2-5 seconds. PM generator only produces a voltage signal if drive wheels are turning greater than 3 MPH.
2. Before replacing control module, PROM/MEM-CAL should be checked for correct application.

A faulty or misadjusted park/neutral switch may set a false Code 24. Use scan tester to check for proper signal in Drive while wiggling shifter. Code 24 may set if vehicle is power braked (brakes applied and throttle depressed) for more than 10 seconds.

Scheme 116

Scheme 117

Scheme 118

CODE 27, QUAD-DRIVER NO. 1 ERROR 2.3L "N" BODY

PCM controls most components with electronic switches completing a ground circuit when actuated. Switches are arranged in groups of 4, called Quad-Driver Modules (QDMs), which can independently control up to 4 outputs (control module terminals). When an output is actuated, terminal is grounded and its voltage normally will be low. When an output is off, its terminal voltage will normally be high.

QDMs are fault-protected. If a relay or solenoid coil is shorted (having very low resistance) or if control side of circuit is shorted to voltage, too much current would be allowed into QDM. QDM senses this and turns driver off or QDM's internal resistance increases to limit current flow and protect QDM. Result is high output terminal voltage when it should be low. If circuit from battery voltage or component is open or control side of circuit is shorted to ground, terminal voltage will be low, even when output is turned off. Either of these conditions is considered to be a QDM fault.

Each QDM has a separate fault line to indicate presence of a current fault to control module central processor. A scan tester displays status of each of these fault lines as "low equals okay" or "high equals fault". Because of the brake and 2nd gear switches in the TCC circuit, Code 27 will set if QDM No. 1 is high for 20 seconds or more with battery voltage is sensed at greater than 10.5 volts and TCC is commanded on.

Scheme 119

Scheme 120

CODE 28, GEAR RANGE SWITCH CIRCUIT 3.1L "L" & "W"

Gear range switch contacts are part of neutral start switch. Contacts close to ground or open in different positions of gear selector. Code 28 will set if incorrect combination of signals occur for more than 10 seconds.

Note. Test numbers refer to numbers on diagnostic chart.

1. This tests for proper operation of gear range switch.
2. This tests for proper operation of gear range switch.
3. This tests for an open, grounded or shorted wire in battery positive circuit.

An intermittent may be caused by a poor connection, chaffed wire insulation or a broken wire.

Scheme 121

Scheme 122

CODE 28, GEAR RANGE SWITCH CIRCUIT 3.1L "N"

Gear range switch contacts are part of neutral start switch. Contacts close to ground or open in different positions of gear selector. Code 28 will set if incorrect combination of signals occur for more than 10 seconds.

Note. Test numbers refer to numbers on diagnostic chart.

1. This tests for proper operation of gear range switch.
2. This tests for proper operation of gear range switch.
3. This tests for an open, grounded or shorted wire in battery positive circuit.

An intermittent may be caused by a poor connection, chaffed wire insulation or a broken wire. Monitor voltage of each terminal while moving related harness connectors. If failure is induced, voltage reading will change.

Scheme 123

Scheme 124

CODE 29, QUAD-DRIVER NO. 3 ERROR 2.3L "N" BODY

PCM controls most components with electronic switches completing a ground circuit when actuated. Switches are arranged in groups of 4, called Quad-Driver Modules (QDMs), which can independently control up to 4 outputs (control module terminals). When an output is actuated, terminal is grounded and its voltage normally will be low. When an output is off, its terminal voltage will normally be high; except for TCC (which depends on brake and 2nd gear TCC switches.

QDMs are fault-protected. If a relay or solenoid coil is shorted (having very low resistance) or if control side of circuit is shorted to voltage, too much current would be allowed into QDM. QDM senses this and turns driver off or QDM's internal resistance increases to limit current flow and protect QDM. Result is high output terminal voltage when it should be low. If circuit from battery voltage or component is open or control side of circuit is shorted to ground, terminal voltage will be low, even when output is turned off. Either of these conditions is considered to be a QDM fault.

Each QDM has a separate fault line to indicate presence of a current fault to control module central processor. A scan tester displays status of each of these fault lines as "low equals okay" or "high equals fault". Code 29 will set if QDM No. 3 is high for 20 seconds or more with battery voltage is sensed at greater than 10.5 volts.

Note. Test numbers refer to numbers on diagnostic chart and are not necessarily in order.

1. 1) This tests for PCM ability to ground shift solenoids "A" and "B".
2. 2) This tests for scan testers ability to ground shift solenoids "A" and "B".
3. 3) This tests for short to voltage on shift solenoids "A" and "B".
4. 5) This test for PCM ability to ground TCC Pulse Width Modulator (PWM) solenoid.
5. 6) This test for scan testers ability to ground TCC Pulse Width Modulator (PWM) solenoid.

Scan tester should be able to turn shift and TCC PWM solenoids on. A faulty connection or open circuit can result in a Code 29.

Scheme 125

Scheme 126

Note. Test number refers to numbers on diagnostic chart.

1. 4) This step tests for continuity of the shift solenoid circuits.

Scan tester should be able to turn shift and TCC PWM solenoids on. A faulty connection or open circuit can result in a Code 29.

Scheme 127

CODE 38, BRAKE SWITCH CIRCUIT

Code 38 will set if no Code 24 is present, status at brake input terminal of control module has not changed from high to low and vehicle speed has been greater than 35 MPH and back to zero MPH a precalibrated number of times.

Note. Test numbers refer to test numbers on diagnostic chart.

1. Jumpering the brake switch determines if the PCM and wiring for brake switch are okay.
2. Determines if brake switch is out of adjustment or is faulty.
3. Verifies the voltage to the brake switch.

A Code 38 in conjunction with a Code 26, 39 or 56 would mean a problem with one or more of the following components

1. Fuse or power supply circuit, brake switch or wire before the splice.
2. Code 38 alone is the result of a wire or circuit problem between the splice and the control module, poor connection to the control module, or possibly the control module itself.

If brake switch has failed in an open state, TCC will not engage. Code 38 does not turn on SERVICE ENGINE SOON light on all models.

Scheme 128

Scheme 129

Scheme 130

Scheme 131

CODE 58, TRANS. TEMPERATURE SENSOR HIGH TEMPERATURE 3.1L "L", "N" & "W" BODIES

PCM supplies and monitors a 5-volt reference to sensor. As transaxle temperature changes, sensor resistance changes, affecting monitored voltage. When fluid is cold, resistance is high, resulting in a high monitored voltage. When fluid is hot, resistance is low, resulting in a low monitored voltage.

Note. Test number refer to number on diagnostic chart.

1. Checks for a short to ground or an out-of-calibration sensor.
2. Checks for an internal fault within the transaxle by creating an open.

Use TEMPERATURE-TO-RESISTANCE VALUES table to check sensor at various levels to determine if sensor is out-of-calibration, which could result in firm shifts or TCC enable.

Scheme 132

Scheme 133

Scheme 134

Scheme 135

CODE 59, TRANS. TEMPERATURE SENSOR LOW TEMPERATURE 3.1L "L", "N" & "W" BODIES

PCM supplies and monitors a 5-volt reference to sensor. As transaxle temperature changes, sensor resistance changes, affecting monitored voltage. When fluid is cold, resistance is high, resulting in a high monitored voltage. When fluid is hot, resistance is low, resulting in a low monitored voltage.

Note. Test numbers refer to numbers on diagnostic chart.

1. Checks for an out-of-calibration sensor.
2. Simulates a Code 58. If PCM recognizes low signal voltage, and scan displays 146 degrees centigrade or higher, PCM and wiring are okay.
3. Checks if signal circuit is open. Five volts should be present at sensor connector.

A faulty connection or an open ground circuit could result in Code 59. Use TEMPERATURE-TO-RESISTANCE VALUES table to check sensor at various levels to determine if sensor is out-of-calibration, which could result in firm shifts or TCC enable.

Note. For circuit diagrams (Scheme 132)-28.

Scheme 136

CODE 72, VEHICLE SPEED SENSOR LOSS 3.1L "L" & "W" BODIES

Speed sensor is a PM generator located on transaxle output shaft. The voltage level and frequency of pulses increases with vehicle speed.

Note. Test numbers refer to numbers on diagnostic chart.

1. Wheels must be turning faster than 3 MPH for speed sensor to generate a signal.
2. An intermittent connection at VSS or PCM may cause code to set. Inspect harness and all related connections. Check for damage or pushed out terminals.
3. Ensure harness is not routed too close to hot exhaust components.

Code 24 will set if vehicle speed is not detected at start off. Code 72 will set when vehicle speed has been detected and then lost. Check circuits for loose or weak connections.

Scheme 137

CODE 79, TRANSAXLE FLUID OVERTEMP 3.1L ""N" & "W" BODIES

PCM supplies and monitors a 5-volt reference to sensor. As transaxle temperature changes, sensor resistance changes, affecting monitored voltage. When fluid is cold, resistance is high, resulting in a high monitored voltage. When fluid is hot, resistance is low, resulting in a low monitored voltage. If vehicle is driven hard for an extended period, Code 79 will be set to alert driver of transaxle fluid temperature being too high.

Note. Test number refer to number on diagnostic chart.

1. Simulates conditions for Code 79 to reappear.

Check transaxle fluid level. Use TEMPERATURE-TO-RESISTANCE VALUES table to check sensor at various levels to determine if sensor is out-of-calibration. Check for signal circuit for possible short to ground.

Scheme 138

CODE 80/90, TRANSAXLE COMPONENT SLIPPING 3.1L "L", "N" & "W" BODIES

PCM monitors difference between engine speed and transaxle input shaft speed. With selector in D3 or D4 (indicated gear 3 or 4), and TCC is locked, scan should display engine speed closely matching input speed.

Note. Test numbers refer to numbers on diagnostic chart.

1. Checks for a shorted internal transaxle harness or TCC solenoid.
2. Checks for open in power supply to TCC solenoid.

Check all connections to transaxle pass-through connector. An open in the ignition feed circuit will cause multiple codes to set. If scan tester indicates TCC is working, road test vehicle. If engine RPM does not decrease when TCC engagement is indicated on TCC, diagnose transaxle for possible mechanical problem.

Scheme 139

CODE 501/502, VEHICLE SPEED SENSOR 3.1L "A" BODY, 3.4L "W" BODY, 3.8L "C", "H", "U" & "W" BODIES

Speed sensor, which is a Permanent Magnet (PM) generator, provides control module with vehicle speed information. PM generator, mounted in transaxle, produces a pulsing AC voltage signal whenever vehicle speed is greater than 3 MPH. Voltage level and pulses increase with vehicle speed. Control module converts pulsing voltage to MPH, which is used by control module to calculate vehicle adjustments.

Note. Test numbers refer to numbers on diagnostic chart.

1. Wheels must be turning faster than 3 MPH for speed sensor to generate a signal.
2. Before replacing control module, PROM/MEM-CAL should be checked for correct application.

Use scan tester to check for proper signal in Drive while vehicle is moving. Check related circuits for weak or loose connections.

Scheme 140

Scheme 141

Scheme 142

Scheme 143

Scheme 144

CODE 705, GEAR RANGE SWITCH CIRCUIT

Gear range switch contacts are part of neutral start switch. Contacts close to ground in various combinations to indicate each gear range. The voltage level of each switch is indicated as low (grounded circuit) or high (open circuit). Code 705 will set if conditions occur as follows

1. Ignition is ON and engine is OFF.
2. Vehicle speed is zero.
3. Transmission is in high gear.
4. Gear range switch inputs indicate a gear other than park or neutral.
5. All above conditions have been met for at least 10 seconds. NOTE: Test numbers refer to numbers on diagnostic chart. 1) This tests for proper operation of gear range switch. 2) This tests for an open or grounded circuit.

An intermittent may be caused by a poor connection, chaffed wire insulation or a broken wire. Monitor voltage of each terminal while moving related harness connectors. If failure is induced, voltage reading will change.

Scheme 145

Scheme 146

Scheme 147

Scheme 148

Scheme 149

CODE 712, TRANSAXLE TEMPERATURE SENSOR SIGNAL VOLTAGE LOW

PCM sends a voltage signal to sensor and monitors the return voltage. Transaxle temperature sensor varies resistance as temperature of transaxle fluid changes. Temperature sensor resistance is high when transaxle fluid is cold. As fluid temperature increases, sensor resistance decreases. At normal operating temperature, transaxle temperature sensor signal voltage will be about 2 volts.

Note. Test numbers refer to test numbers on diagnostic chart.

1. Code 712 indicates the control module has seen low sensor voltage signal (low temperature) at control module terminal for a precalibrated period of time. This checks if conditions for Code 712 still exist.
2. This simulates conditions for a Code 713. If PCM sets Code 713, wiring between control module and sensor, and PCM are okay.

After the engine is started, temperature should rise steadily to about 190°F (88°C). Check sensor for shifted calibration by using sensor TEMPERATURE-TO-RESISTANCE VALUES table. An intermittent may be caused by a poor connection, chaffed wire insulation or a broken wire. Monitor voltage of each terminal while moving related harness connectors. If failure is induced, voltage reading will change.

Scheme 150

Scheme 151

Scheme 152

Scheme 153

CODE 713, TRANSAXLE TEMPERATURE SENSOR SIGNAL VOLTAGE HIGH

PCM sends a voltage signal to sensor and monitors the return voltage. Transaxle temperature sensor varies resistance as temperature of transaxle fluid changes. Temperature sensor resistance is high when transaxle fluid is cold. As fluid temperature increases, sensor resistance decreases. At normal operating temperature, transaxle temperature sensor signal voltage will be about 2 volts.

Note. Test numbers refer to test numbers on diagnostic chart.

1. Code 713 indicates control module has seen low resistance in transaxle temperature sensor circuit. This checks if conditions for Code 713 still exist.
2. This test determines if coolant sensor signal circuit is grounded.

After the engine is started, temperature should rise steadily to about 190°F (88°C). Check sensor for shifted calibration by using sensor TEMPERATURE-TO-RESISTANCE VALUES table. An intermittent may be caused by a poor connection, chaffed wire insulation or a broken wire. Monitor voltage of each terminal while moving related harness connectors. If failure is induced, voltage reading will change.

Note. For circuit schematics (Scheme 150)-51.

Scheme 154

CODE 740, TCC CIRCUIT

PCM monitors difference between engine speed and transaxle input shaft speed. With selector in D3 or D4 (indicated gear 3 or 4), and TCC is locked, scan should display engine speed closely matching input speed. PWM solenoid is used to vary hydraulic pressure to converter clutch regulator valve which causes a smooth TCC engagement.

Code 740 will set when vehicle is in 3rd or 4th gear, brake is not applied, TCC is commanded by PCM and engine speed-to-vehicle speed ratio does not indicate TCC has engaged. All these conditions must have been met for more than 10 seconds.

Note. Test numbers refer to numbers on diagnostic chart.

1. Tests PCM control circuits and TCC solenoid.
2. Tests fuse, brake switch, battery power circuits to transaxle connector.
3. This tests for internal shorts or grounds at transaxle connector.

Check all connections to transaxle pass-through connector. An open in the ignition feed circuit will cause multiple codes to set. If scan tester indicates TCC is working, road test vehicle. If engine RPM does not decrease when TCC engagement is indicated on TCC, diagnose transaxle for possible mechanical problem.

Scheme 155

Scheme 156

Scheme 157

Scheme 158

CODE 755, SHIFT SOLENOID "B" PROBLEM

The 4T60E is an electronically shifted transaxle. Within the transaxle are 4 solenoids for shift and TCC control. Solenoid "A" is energized for 1st through 4th gear operation. Solenoid "B" is energized for 1st gear as well as all 2nd gear operations. The other 2 solenoids are for TCC operation. This trouble code chart deals with shift control solenoids only. When the ignition is turned on, both solenoids "A" and "B" receive battery voltage. The PCM will ground both solenoid drivers for 1st gear until a shift to 2nd gear is commanded. When vehicle speed and TPS reach calibrated values, the PCM will turn off the ground for solenoid "A" and 2nd gear is engaged. Further increase in vehicle speed will cause PCM to turn off the ground for solenoid "B", engaging 3rd gear. When appropriate speed is reached, PCM will again ground solenoid "A" and 4th gear is engaged.

All PRNDL indications are ignored as far as transaxle shifting is concerned except for manual low gear. If the PRNDL inputs indicate manual low has been selected, the PCM will keep both solenoids "A" and "B" energized until about 5400 RPM, when the PCM will force a shift by de-energizing solenoid "A". Manual 2nd and manual 3rd are controlled hydraulically within the transaxle.

Code 755 will not cause the SERVICE ENGINE SOON light to illuminate. When Code 755 is set, the transaxle will be forced into 3rd gear. If code is due to a grounded solenoid "B" driver circuit, only 1st and 2nd gear operation will be available. If code is due to an open in solenoid "B" driver circuit, only 3rd and 4th gear will be available. When the fault goes away, normal operation will be available for the balance of the key cycle.

Scheme 159

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Scheme 161

Scheme 162

CODE 1640, QUAD-DRIVER ERROR 3.1L "A" BODY

PCM uses Quad-Driver Modules (QDMs) to control several devices. When PCM is commanding a component on, voltage of output circuit will be low (near zero volts). When PCM is commanding component off, voltage of output circuit will be high (near battery voltage). Primary function of quad-driver module is to control ground circuit for component being controlled. PCM has an internal fault line for each quad-driver module. Fault line status can be displayed on a scan tester. If PCM detects an output voltage other than what is expected on fault line, PCM will set Code 1640.

Quad-Driver Related Symptoms

1. Improper shifting.
2. TCC will not apply or harsh engagement.
3. Poor driveability due to constant EGR. NOTE: Test numbers refer to numbers on diagnostic chart. 1) If other QDM-related codes are present, use those charts first. Repairing other related code problems will also fix Code 1640. 2) This step will check each circuit to determine which is at fault.

Monitor voltage at each terminal shown in schematic while moving related harness connectors, including PCM harness. If failure is induced, voltage will change. This may help to isolate an intermittent condition. Check for bent pins at PCM. If code reoccurs with no apparent connection problem, replace PCM.

Scheme 163

CODE 1640, QUAD-DRIVER ERROR 3.4L "W" BODY

PCM uses Quad-Driver Modules (QDMs) to control several devices. When PCM is commanding a component on, voltage of output circuit will be low (near zero volts). When PCM is commanding component off, voltage of output circuit will be high (near battery voltage). Primary function of quad-driver module is to control ground circuit for component being controlled. PCM has an internal fault line for each quad-driver module. Fault line status can be displayed on a scan tester. If PCM detects an output voltage other than what is expected on fault line, PCM will set Code 1640.

1. Improper shifting.
2. TCC will not apply or harsh engagement.
3. Poor driveability due to constant EGR. NOTE: Test numbers refer to numbers on diagnostic chart. 1) PCM does not know which controlled circuit caused Code 1640 to set. This chart will check each circuit to determine which is at fault. If other QDM-related codes are present, use those charts first. 2) If QDM "A" related symptoms are present, check for Code 740. If Code 740 is present, repair Code 740 first. 3) These steps help determine which circuit is out of specification. 4) This test will determine if the problem is the circuit or the component. As the factory installed PCM is protected by an internal circuit breaker, it is unlikely that the PCM needs to be replaced.

Monitor voltage at each terminal shown in schematic while moving related harness connectors, including PCM harness. If failure is induced, voltage will change. This may help to isolate an intermittent condition. Check for bent pins at PCM. If code reoccurs with no apparent connection problem, replace PCM.

Scheme 164

Scheme 165

Note. Test number refer to number on diagnostic chart.

1. 5) This step determines which circuit is out of specification.

Scheme 166

CODE 1640, QUAD-DRIVER ERROR 3.8L "C", "H", "U" & "W" BODIES

PCM uses Quad-Driver Modules (QDMs) to control several devices. When PCM is commanding a component on, voltage of output circuit will be low (near zero volts). When PCM is commanding component off, voltage of output circuit will be high (near battery voltage). Primary function of quad-driver module is to control ground circuit for component being controlled. PCM has an internal fault line for each quad-driver module. Fault line status can be displayed on a scan tester. If PCM detects an output voltage other than what is expected on fault line, PCM will set Code 1640.

Note. Test numbers refer to numbers on diagnostic chart.

1. If other QDM-related codes are present, use those charts first. Repairing other related code problems will also fix Code 1640.
2. These steps help determine which circuit is out of specification. If related symptoms are present, checks on Code 1640 (2 of 2) chart should isolate cause of fault.
3. These steps help determine which circuit is out of specification.

Monitor voltage at each terminal shown in schematic while moving related harness connectors, including PCM harness. If failure is induced, voltage will change. This may help to isolate an intermittent condition. Check for bent pins at PCM. If code reoccurs with no apparent connection problem, replace PCM.

Scheme 167

Scheme 168

Scheme 169

Note. Test numbers refer to numbers on diagnostic chart.

1. 4) This test will determine if the problem is the circuit or the component.
2. 5) As the factory installed PCM is protected by an internal circuit breaker, it is unlikely that the PCM needs to be replaced.

Scheme 170

CODE 1650, QUAD-DRIVER ERROR 3.1L "A" BODY

PCM uses Quad-Driver Modules (QDMs) to control several devices. When PCM is commanding a component on, voltage of output circuit will be low (near zero volts). When PCM is commanding component off, voltage of output circuit will be high (near battery voltage). Primary function of quad-driver module is to control ground circuit for component being controlled. PCM has an internal fault line for each quad-driver module. Fault line status can be displayed on a scan tester. If PCM detects an output voltage other than what is expected on fault line, PCM will set Code 1650.

1. Improper shifting.
2. TCC will not apply or harsh engagement.
3. Poor driveability due to constant EGR.

Monitor voltage at each terminal shown in schematic while moving related harness connectors, including PCM harness. If failure is induced, voltage will change. This may help to isolate an intermittent condition. Check for bent pins at PCM. If code reoccurs with no apparent connection problem, replace PCM.

Scheme 171

CODE 1650, QUAD-DRIVER ERROR 3.4L "W" BODY

PCM uses Quad-Driver Modules (QDMs) to control several devices. When PCM is commanding a component on, voltage of output circuit will be low (near zero volts). When PCM is commanding component off, voltage of output circuit will be high (near battery voltage). Primary function of quad-driver module is to control ground circuit for component being controlled. PCM has an internal fault line for each quad-driver module. Fault line status can be displayed on a scan tester. If PCM detects an output voltage other than what is expected on fault line, PCM will set Code 1650.

Note. Test numbers refer to numbers on diagnostic chart.

1. If other QDM-related codes are present, use those charts first. Repairing other related code problems will also fix Code 1650.
2. These steps help determine which circuit is out of specification. If related symptoms are present, checks on Code 1650 (2 of 2) chart should isolate cause of fault.
3. These steps help determine which circuit is out of specification.

Monitor voltage at each terminal shown in schematic while moving related harness connectors, including PCM harness. If failure is induced, voltage will change. This may help to isolate an intermittent condition. Check for bent pins at PCM. If code reoccurs with no apparent connection problem, replace PCM.

Scheme 172

Scheme 173

Note. Test numbers refer to numbers on diagnostic chart.

1. 4) This test will determine if the problem is the circuit or the component.
2. 5) As the factory installed PCM is protected by an internal circuit breaker, it is unlikely that the PCM needs to be replaced.

Scheme 174

CODE 1650, QUAD-DRIVER ERROR 3.8L "C", "H", "U" & "W" BODIES

PCM uses Quad-Driver Modules (QDMs) to control several devices. When PCM is commanding a component on, voltage of output circuit will be low (near zero volts). When PCM is commanding component off, voltage of output circuit will be high (near battery voltage). Primary function of quad-driver module is to control ground circuit for component being controlled. PCM has an internal fault line for each quad-driver module. Fault line status can be displayed on a scan tester. If PCM detects an output voltage other than what is expected on fault line, PCM will set Code 1650.

Note. Test numbers refer to numbers on diagnostic chart.

1. If other QDM-related codes are present, use those charts first. Repairing other related code problems will also fix Code 1650.
2. These step determines which circuit is out of specification.

Monitor voltage at each terminal shown in schematic while moving related harness connectors, including PCM harness. If failure is induced, voltage will change. This may help to isolate an intermittent condition. Check for bent pins at PCM. If code reoccurs with no apparent connection problem, replace PCM.

Scheme 175

Scheme 176

Scheme 177

Note. Test numbers refer to numbers on diagnostic chart.

1. 3) This test will determine if the problem is the circuit or the component.
2. 4) As the factory installed PCM is protected by an internal circuit breaker, it is unlikely that the PCM needs to be replaced.

Scheme 178

ELECTRONIC TESTING

Note. On all vehicles with transaxle model CMW (used on 3.1L and 3.4L engines) cannot use the test box to diagnose components. On these vehicles, go to COMPONENT TESTS (WITHOUT TEST BOX) .

Note. The following procedures check operation of electronic control of 4T60-E transaxle. These tests are also found in appropriate SYSTEM/COMPONENT TESTS article in the ENGINE PERFORMANCE section.

Scheme 179

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 vehicle harness connector. (Scheme 179) Connect a bidirectional scan tester or Tech 1 (94-00101 A) to ALDL or enter on-board self-diagnostics. 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 180)
4. Road test the vehicle and note LED indicators on test box. If a problem is present (indicated by test box LEDs), the TEST BOX DIAGNOSTIC FLOW CHART will refer you to the next procedure or chart. (Scheme 181)-85. See appropriate procedures under COMPONENT TESTS.

Scheme 180

COMPONENT TESTS (WITH TEST BOX)

Note. Before using the following charts, see TESTING EQUIPMENT & PROCEDURES under ELECTRONIC TESTING . On all vehicles with transaxle model CMW (used on 3.1L and 3.4L engines), do not use the test box to diagnose components. On these vehicles, go to COMPONENT TESTS (WITHOUT TEST BOX) .

Scheme 181

Scheme 182

Scheme 183

Scheme 184

Scheme 185

Scheme 186

COMPONENT TESTS (WITHOUT TEST BOX)

Note. The following tests will determine if an electrical problem exists in transaxle or vehicle. For the purpose of these tests, include all transaxle model CMW.

Scheme 187

Scheme 188

Scheme 189

Scheme 190

Scheme 191

Scheme 192

4T60-E Wiring Diagram (Achieva, Grand Am & Skylark - 2.3L). Scheme 193

4T60-E Wiring Diagram (Achieva, Grand Am & Skylark - 3.1L). Scheme 194

4T60-E Wiring Diagram (Beretta & Corsica). Scheme 195

4T60-E Wiring Diagram (Bonneville, Eighty Eight & Ninety Eight). Scheme 196

4T60-E Wiring Diagram (Century & Ciera). Scheme 197

4T60-E Wiring Diagram (Lumina - VIN T). Scheme 198

4T60-E Wiring Diagram (Cutlass Supreme, Grand Prix & Lumina - VIN X). Scheme 199

4T60-E Wiring Diagram (Cutlass Supreme, Grand Prix & Regal - VIN M). Scheme 200

4T60-E Wiring Diagram (Regal - VIN L, 3.8L). Scheme 201

4T60-E Wiring Diagram (Lumina APV, Silhouette & Trans Sport). Scheme 202

4T60-E Wiring Diagram (LeSabre & Park Avenue). Scheme 203

See also:
• CLUTCH & BAND APPLICATION CHART (4T60-E)
• ELECTRONIC TESTING
• COMPONENT TESTS (WITHOUT TEST BOX)