Diagnosis - 4t60-e Buick LeSabre VII

APPLICATION

4T60-E TRANSAXLE 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 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, 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.

On DeVille, PCM is also connected to one or more other computers, which operate climate control system, anti-lock brake system, driver information center and supplemental restraint system.

SENSORS & SWITCHES

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

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 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 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. Depending on vehicle, several methods may be used. The most basic method (non-scan) uses a jumper wire to activate MIL, which will flash a series of codes.

Other methods include using a factory recommended Tech 1 scan tool, aftermarket scan tool or instrument panel mounted display (DeVille only).

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

CLUTCH & BAND APPLICATIONS

CLUTCH & BAND APPLICATION CHART (4T60-E)

ELECTRONIC SELF-DIAGNOSTICS (EXCEPT CADILLAC)

Note. To test electronic control of transaxle solenoids without using self-diagnostics or if self-diagnostics does not function, 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 (EXCEPT CADILLAC).

RETRIEVING CODES (WITHOUT SCAN TOOL)

Note. Following procedure is for vehicles equipped with a 12-pin Data Link Connector (DLC). On vehicles equipped with 16-pin DLC (OBD-II vehicles), DTCs can only be retrieved using scan tool.

Scheme 35

1. Turn ignition on. DO NOT start engine. MIL should glow. Locate Data Link Connector (DLC) attached to control module wiring harness. Most DLCs are located under dash on driver's side of vehicle. Turn ignition on with engine not running. Connect jumper wire from terminal "B" (diagnostic test terminal) to terminal "A" (ground) of DLC. (Scheme 35) NOTE: Inserting jumper wire into test and ground terminals of DLC with engine running will cause fuel injected vehicles to enter field service mode. MIL will not indicate codes if this is done. NOTE: On vehicles equipped with 2.3L engine, Code 12 should always exist when DLC is grounded with Key On and Engine Off (KOEO).
2. MIL should begin to flash codes. Each code will be repeated 3 times. For example, FLASH, FLASH, pause, FLASH, longer pause, identifies Code 21. First series of flashes is first digit of trouble code. Second series of flashes is second digit of trouble code.
3. Trouble codes are displayed starting with lowest numbered code. Codes will continue to repeat as long as DLC test terminal is grounded. If codes are not flashed, or MIL does not glow, self-diagnostics will not work. For diagnosis of this condition, 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 DLC.

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 tool into DLC enables user to read trouble codes 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.

Note. On vehicles equipped with 2.3L engine, Code 12 should always exist when DLC is grounded with Key On and Engine Off (KOEO), but may not be indicated by all makes of scan tools.

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.

Note. If erroneous voltage signals are suspected, it will be necessary to verify scan tool information using a digital voltmeter and wiring schematic. If non-existent codes are displayed, turn ignition off, remove scan tool, turn ignition on and ground DLC test terminal "B". (Scheme 35) Same codes flashed by MIL should be indicated by scan tool.

TROUBLE CODE DEFINITIONS

Note. Only transaxle-related trouble codes are listed. For engine-related DTCs, see appropriate TESTS W/CODES article in the ENGINE PERFORMANCE section. 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 (2.3L)

PCM TROUBLE CODE DEFINITIONS (3.1L, 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. Enter diagnostic mode. See RETRIEVING CODES. Read and record all stored trouble codes. Exit diagnostic mode and clear trouble codes. See «CLEARING TROUBLE CODES»(/buick/lesabre/vii-1992-1999/remont/automatic-trans/#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 DTC. If MIL does not come on, all stored DTCs were intermittent failures.

CLEARING TROUBLE CODES

Turn ignition switch to ON position, and ground diagnostic test terminal "B" at DLC connector. (Scheme 35) Turn ignition switch to OFF position, and remove control module fuse from fuse block for 30 seconds. Replace fuse. Remove diagnostic terminal ground lead. If fuse cannot be located, disconnect pigtail at battery. 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.

Diagnostic Charts

Following charts are DTC specific. For terminal locations, see WIRING DIAGRAMS . For engine-related DTCs, see appropriate TESTS W/CODES 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. In the following diagnostic tests, schematics and illustrations are courtesy of General Motors Corp.

Code 21 2.3L "N" Body - Circuit Diagram. Scheme 36

CODE 21 PCM TERMINAL & CIRCUIT WIRING IDENTIFICATION

1. For shared sensor ground tie-offs, see appropriate chassis wiring diagram in WIRING DIAGRAMS article.

Code will set if engine is idling (closed throttle), MAP value is low, a MAP code is not set and PCM sees high TP sensor voltage. Most likely causes for code are: TP sensor signal circuit shorted to voltage, open sensor ground circuit, faulty sensor connection, faulty TP sensor or faulty PCM. Code inhibits TCC and 4th gear.

Note. Test numbers refer to numbers on diagnostic chart.

1. This test checks if code is result of a hard failure or an intermittent condition.
2. This test simulates a low-voltage condition. If control module recognizes change of state, 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, an accompanying code related to that sensor may exist.

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.

Code 21 2.3L "N" Body - Troubleshooting Diagram. Scheme 37

CODE 22: THROTTLE POSITION SENSOR SIGNAL VOLTAGE LOW - 2.3L "N" BODY

CODE 22 PCM TERMINAL & CIRCUIT WIRING IDENTIFICATION

1. For shared sensor ground tie-offs, see appropriate chassis wiring diagram in WIRING DIAGRAMS article.

Code will set if engine is running and TP sensor voltage is lower than base idle voltage (auto zero voltage). Most likely causes of code are: TP sensor signal circuit open or shorted to ground, 5-volt reference open or shorted to ground (should also set other codes), faulty sensor connection, faulty sensor, faulty PCM connection or faulty PCM. Code inhibits TCC and 4th gear.

Note. Test numbers refer to numbers on diagnostic chart.

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

Code 22 2.3L "N" Body - Troubleshooting Diagram. Scheme 38

Code 24, 2.3L "N" Body - Circuit Diagram. Scheme 39

Speed sensor, which is a Permanent Magnet (PM) generator, provides control module with vehicle speed information. PM generator, mounted in transmission, produces a pulsing AC voltage signal whenever vehicle speed is greater than about 2 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. TCC is disabled and transaxle defaults to 3rd gear.

Note. Test numbers refer to numbers on diagnostic chart.

1. PM generator only produces a voltage signal if drive wheels are turning greater than about 2 MPH.

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.

Code 24, 2.3L "N" Body - Troubleshooting Diagram. Scheme 40

Code 27 2.3L "N" Body - Circuit Diagram. Scheme 41

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 3rd gear switches in the TCC circuit, Code 27 will set if QDM No. 1 is high for 20 seconds or more with battery voltage sensed at greater than 10.5 volts and TCC is commanded on.

Note. Test numbers refer to numbers on diagnostic chart.

1. Checks if code was set as a result of EVAP canister purge valve circuit.
2. Checks TCC operation.
3. Checks shift light operation.

Tech 1 has the ability to command EVAP purge valve and shift light on and off. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connections or damaged harness.

Perform intermittent check by monitoring circuit and code status while wiggling related wiring and connectors. If failure is induced, monitored circuit status will change rapidly and/or related code will set.

Code 27 2.3L "N" Body - Trouble Shooting Diagram. Scheme 42

Code 29 2.3L "N" Body - Circuit Diagram. Scheme 43

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". Code 29 will set if QDM No. 2 is high for 20 seconds or more with battery voltage sensed at greater than 10.5 volts.

Note. Test numbers refer to numbers on diagnostic chart.

1. 1 Checks if PCM is grounding shift solenoids "A" and "B".
2. 2 Checks to see if Tech 1 can command shift solenoids.
3. 3 Checks for short to voltage on shift solenoid circuits.
4. 5 Checks to see if PCM is grounding TCC PWM.
5. 6 Checks to see if PCM can command TCC PWM.

Tech 1 has the ability to command shift solenoids and TCC PWM on and off. A faulty connection or an open circuit can result in setting Code 29. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connections or damaged harness.

Perform intermittent check by monitoring circuit and code status while wiggling related wiring and connectors. If failure is induced, monitored circuit status will change rapidly and/or related code will set.

Code 29 2.3L "N" Body - Troubleshooting Diagram (1 Of 2). Scheme 44

Note. Test numbers refer to numbers on diagnostic chart.

Checks continuity of shift solenoid circuits.

Code 29 2.3L "N" Body - Troubleshooting Diagram (2 Of 2). Scheme 45

Code 53 2.3L "N" Body - Circuit Diagram. Scheme 46

This code indicates a basic charging system problem. Code 53 will set when voltage at control module terminal is greater than specification for a precalibrated time. If voltage at PCM battery voltage terminal is not within specification, check and repair charging system. TCC is disabled and transaxle defaults to 3rd gear.

CHARGING SYSTEM SPECIFICATIONS

Code 53 2.3L "N" Body - Troubleshooting Diagram. Scheme 47

Circuit Descriotion

Throttle Position (TP) sensor provides a voltage signal that changes relative to throttle blade angle. Signal voltage will vary from about .20-.74 volt at idle to greater than 4 volts at Wide Open Throttle (WOT). TP sensor signal is one of the most important inputs used by PCM for fuel control and for most of PCM control outputs. Code inhibits TCC and 4th gear.

Set Condition

Code P0122 will set when the following conditions are present.

1. Ignition on.
2. TP sensor signal voltage is less than about .2 volt for a precalibrated time.

Test Description

Note. Test numbers refer to numbers on diagnostic chart.

1. Determines if conditions necessary to set Code P0122 exist.
2. Simulates Code P0123 (high voltage). If PCM recognizes high signal voltage and sets Code P0123, PCM and wiring are okay.
3. Simulates a high signal voltage. Checks signal circuit for an open.

Code P0122 3.1L "A" Body - Circuit Diagram. Scheme 48

Code P0122 3.4L "W" Body - Circuit Diagram. Scheme 49

Code P0122 3.8L "C", "G" & "H" Body - Circuit Diagram. Scheme 50

Code P0122 3.1L "W" Body - Circuit Diagram. Scheme 51

Scan tester displays throttle position in volts. Voltage should increase steadily as throttle is moved toward WOT. An open or short to ground in reference and signal circuits will cause Code P0122 to set. Check for

Poor Connection Or Damaged Harness

Inspect PCM harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.

Intermittent Test

Monitor TP sensor voltage display on scan tester while moving related connectors and wiring harness. If failure is induced, display will change. This may assist in isolating location of malfunction.

TP Sensor Scaling

Observe TP sensor voltage display while depressing accelerator pedal with engine stopped and ignition on. Display should vary from closed throttle TP sensor voltage when throttle is closed (about .20-.74 volt) to greater than 4 volts when throttle is held at WOT position.

Circuit Description

Throttle Position (TP) sensor provides a voltage signal that changes relative to throttle blade angle. Signal voltage will vary from .20-.74 volt at idle to greater than 4 volts at Wide Open Throttle (WOT). TP sensor signal is one of the most important inputs used by control module for fuel control and for most other control module control outputs. Code inhibits TCC and 4th gear.

Note. Test numbers refer to numbers on diagnostic chart.

1. Determines if conditions necessary to set code exist.
2. Simulates Code P0123 (high voltage). If control module recognizes high signal voltage, control module and wiring are okay.
3. Simulates a high signal voltage. Checks signal circuit for an open.

Code P0122 3.8L "U" Body - Circuit Diagram. Scheme 52

Tech 1 displays throttle position in volts. Voltage should increase steadily as throttle is moved toward WOT.

An open or short to ground in reference and signal circuits will cause code to set. Check for

Inspect control module harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.

Monitor TP sensor voltage display on Tech 1 while moving related connectors and wiring harness. If failure is induced, display will change. This may assist in isolating location of malfunction.

Observe TP sensor voltage display while depressing accelerator pedal with engine stopped and ignition on. Display should vary from closed throttle TP sensor voltage when throttle is closed (less than 1.25 volts) to greater than 4.5 volts when throttle is held at WOT position.

Throttle Position (TP) sensor provides a voltage signal that changes relative to throttle blade angle. Signal voltage will vary from .20-.74 volt at idle to about 5 volts at Wide Open Throttle (WOT). TP sensor signal is one of the most important inputs used by PCM for fuel control and for most of PCM control outputs. Code inhibits TCC and 4th gear.

Code P0123 will set when the following conditions are present.

1. TP sensor voltage is greater than 4.8 volts at any time, or engine is running and airflow is less than 17 grams per second.
2. Engine speed is greater than 600 RPM.
3. TP sensor signal voltage is greater than 1.06 volts.
4. Code P0101 is not present.
5. All conditions are met for 5 seconds.

Note. Test numbers refer to numbers on diagnostic chart.

1. With closed throttle, ignition on or idling, voltage at PCM TP sensor signal circuit should be about .20-.74 volt.
2. With TP sensor disconnected, TP sensor voltage should decrease and Code P0122 will set. This test verifies that PCM and wiring are okay.
3. Probing ground circuit with a test light check sensor ground circuit. A faulty sensor ground circuit will cause Code P0123 to set.

Code P0123 "A", "C", "G", "H" & "W" Bodies - Troubleshooting Diagram. Scheme 53

Scan tester displays throttle position in volts. With closed throttle, ignition on, or at idle, voltage should be about .20-.74 volt. If voltage is not as specified, replace TP sensor. An open in sensor ground circuit will cause Codes P0112, P0712, P0117 and P0123 to set. Check for

Inspect PCM harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.

Monitor TP sensor voltage display on scan tester while moving related connectors and wiring harness. If failure is induced, display will change. This may assist in isolating location of malfunction.

Observe TP sensor voltage display while depressing accelerator pedal with engine stopped and ignition on. Display should vary from closed throttle TP sensor voltage when throttle is closed (about .20-.74 volt) to greater than 4 volts when throttle is held at WOT position.

Throttle Position (TP) sensor provides a voltage signal that changes relative to throttle blade angle. Signal voltage will vary from .20-.74 volt or at idle to approximately 5 volts at Wide Open Throttle (WOT). TP sensor signal is one of the most important inputs used by control module for fuel control and for most other control module control outputs. On non-adjustable TPS sensors, each time voltage drops below 1.25 volts and stops, control module assumes this value as 0 throttle angle and measures percent throttle from this point on. Code inhibits TCC and 4th gear.

Note. Test numbers refer to numbers on diagnostic chart.

1. With closed throttle, ignition on, or at idle, voltage at control module TP sensor signal circuit should be .20-.74 volt.
2. With TP sensor disconnected, TP sensor voltage should decrease and Code P0122 will set. This test verifies that control module and wiring are okay.
3. Probing ground circuit with a test light check sensor ground circuit. A faulty sensor ground circuit will cause Code P0123 to set.

Code P0123 3.8L "U" Body - Troubleshooting Diagram. Scheme 54

Tech 1 displays throttle position in volts. With closed throttle, ignition on, or at idle, voltage should be .20-.74 volt. If voltage is not as specified, replace TP sensor. An open in sensor ground circuit will cause Codes P0112, P0712, P0117 and P0123 to set. Check for

Inspect control module harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.

Monitor TP sensor voltage display on Tech 1 while moving related connectors and wiring harness. If failure is induced, display will change. This may assist in isolating location of malfunction.

Observe TP sensor voltage display while depressing accelerator pedal with engine stopped and ignition on. Display should vary from closed throttle TP sensor voltage when throttle is closed (.20-.74 volt) to greater than 4 volts when throttle is held at WOT position.

Vehicle Speed Sensor (VSS) in transaxle provides vehicle speed information to PCM. Voltage level and number of pulses increase with vehicle speed. PCM converts pulsing voltage to MPH, and MPH can be displayed using a scan tester.

Function of VSS buffer, used in past models, has been incorporated into PCM. PCM supplies necessary signal for instrument cluster (4004 pulses per mile) for operating speedometer and odometer.

Set Conditions

Code P0501 will set when the following conditions are present.

1. Engine is running.
2. Code P0703 is not set.
3. Transaxle is out of Park or Neutral for more than 4 seconds.
4. Vehicle speed is greater than 18 MPH.
5. Brake is not applied.
6. All conditions are met for 2 seconds.

Code P0502 will set when the following conditions are present.

1. Vehicle speed goes from less than 3 to zero MPH in less than 2 seconds, brake not applied.
2. Engine is running.
3. Engine speed is greater than 3000 RPM.
4. Transaxle is out of Park or Neutral for more than 4 seconds.

Note. Test numbers refer to numbers on diagnostic chart.

1. VSS signal generator only produces a signal if drive wheels are turning greater than 3 MPH.
2. Check PROM for correct application before replacing PCM.

Scheme 55

Scheme 56

Scheme 57

Scheme 58

Scheme 59

When vehicle speed is greater than about 3 MPH, Tech 1 should indicate a vehicle speed. Code P0502 indicates an intermittent and may not set immediately or under all conditions. Check sensor circuits for proper connections. Ensure they are clean and tight and harness is correctly routed.

The Vehicle Speed Sensor (VSS) in transaxle provides vehicle speed information to control module. Voltage level and number of pulses increase with vehicle speed. Control module converts pulsing voltage to MPH, and MPH can be displayed using a Tech 1.

The function of VSS buffer, used in past models, has been incorporated into control module. Control module supplies necessary signal for instrument cluster (4004 pulses per mile) for operating speedometer and odometer.

With Codes P0501 or P0502 set, cruise control operation will not be allowed. Code will remain set for remainder of that ignition cycle, and control module will command only 2nd and 3rd gear based on RPM and TP sensor. TCC will not be allowed to engage. Instrument cluster speedometer may be inoperative. Codes P0501 and P0502 will illuminate Malfunction Indicator Light (MIL).

Note. Test numbers refer to numbers on diagnostic chart.

1. VSS signal generator only produces a signal if drive wheels are turning greater than 3 MPH.
2. Check PROM for correct application before replacing control module.

Scheme 60

When vehicle is moving greater than 3 MPH, Tech 1 should indicate a vehicle speed. Code P0502 indicates an intermittent and may not set immediately or under all conditions. Check sensor circuits for proper connections. Ensure they are clean and tight and harness is correctly routed.

PCM monitors status of TCC brake switch input. Code P0703 will set when the following conditions are present.

1. Code P0501 is not present.
2. Vehicle speed has been greater than 35 MPH for 10 seconds and back to zero MPH 5 times.
3. TCC brake switch input status has not changed from released to applied, or applied to released as displayed on scan tester.

Scheme 61

Scheme 62

Scheme 63

Scheme 64

Scheme 65

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside insulation. Check for

Inspect PCM harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.

Monitor scan tester while moving related connectors and wiring harness. If failure is induced, scan data will change from released to applied, or applied to released. This may assist in isolating location of malfunction.

Control module monitors status of TCC brake switch. Code 703 will set if conditions occur as follows

1. Codes P0501 or P0502 are not present.
2. Vehicle speed has been above 35 MPH for 10 seconds, and back to zero 5 times.
3. TCC brake switch status has not changed from Released to Applied or Applied to Released as displayed on scan tool.

Scheme 66

An intermittent may be caused by a poor connection, chaffed wire insulation or a broken wire. Check for damaged harness, terminals or broken locks.

Transaxle range switch is part of Transaxle Mounted Neutral Start Switch (TMNSS) mounted on transaxle assembly. Transaxle range switch is a multi-signal switch that sends information, relative to gear selector position, to PCM. PRNDL input consists of 4 discrete circuits to pull 4 PCM voltages low in various combinations to indicate each gear range. Voltage level of each of circuits is represented as low equals grounded circuit and high equals open circuit. The 4 states displayed represent decoder parity, "A", "B" and "C" respectively.

Code P0705 will set when the following conditions are present.

1. Ignition is on and engine off.
2. Vehicle speed is zero MPH.
3. PRNDL inputs indicate a gear other than Park and Neutral.
4. All conditions are met for a predetermined time for 3 consecutive start-ups.

Or

1. PRNDL inputs status indicators ("P", "A", "B"and "C") indicate an incorrect combination of low and high. PCM will also command stepper motor cruise control to be inhibited.

Note. Test numbers refer to numbers on diagnostic chart.

1. This step checks for proper operation of transaxle range switch.
2. This test checks for an open or grounded circuit. When Code P0705 is present, PCM assumes drive-4 position until a correct combination is received by PCM. Some gear selector positions may not be possible until fault is repaired.

Scheme 67

Scheme 68

Scheme 69

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside insulation. Check for

Inspect PCM harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.

Monitor scan tester while moving related connectors and wiring harness. If failure is induced, scan data will change from low to high, or high to low. This may assist in isolating location of malfunction.

Transaxle range switch is part of Transaxle Mounted Neutral Start Switch (TMNSS) mounted on transaxle assembly. Transaxle range switch is a multi-signal switch that sends information, relative to gear selector position, to PCM. PRNDL input consists of 4 discrete circuits to pull 4 PCM voltages low in various combinations to indicate each gear range. Voltage level of each of circuits is represented as low equals grounded circuit and high equals open circuit. The 4 states displayed represent decoder parity, "A", "B"and "C" respectively.

Code P0705 will set when the following conditions are present.

1. Ignition is on and engine off.
2. Vehicle speed is zero MPH.
3. PRNDL inputs indicate a gear other than Park and Neutral.
4. All conditions are met for a predetermined time for 3 consecutive start-ups.

Or

1. PRNDL inputs status indicators ("P", "A", "B"and "C") indicate an incorrect combination of low and high. PCM will also command stepper motor cruise control to be inhibited.

Note. Test numbers refer to numbers on diagnostic chart.

1. 1 & 2) Checks for proper operation of transmission range switch.
2. 3). This test checks for an open or grounded circuit. When Code P0705 is present, PCM assumes drive-4 position until a correct combination is received by PCM. Some gear selector positions may not be possible until fault is repaired.

Scheme 70

Scheme 71

Scheme 72

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside insulation. Check for

Inspect PCM harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.

Monitor scan tester while moving related connectors and wiring harness. If failure is induced, scan data will change from low to high, or high to low. This may assist in isolating location of malfunction.

Transaxle 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).

Set Condittion

Code 705 will set if conditions occur as follows

1. Ignition is on and engine is off.
2. Vehicle speed is zero MPH.
3. Transaxle is in high gear.
4. Transaxle range switch inputs indicate a gear other than Park or Neutral.
5. All conditions have been met for at least 10 seconds.

Note. Test numbers refer to numbers on diagnostic chart.

1. 1 & 2) Tests for proper operation of gear range switch.
2. 3). This tests for an open or grounded circuit.

Scheme 73

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside insulation. Check for

Inspect control module harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.

Using Tech 1, monitor signal voltage while moving related connectors and wiring harness with engine running at part throttle in closed loop. If failure is induced, signal voltage reading will change from high to low or low to high. This may assist in isolating location of malfunction.

Transaxle temperature sensor uses a thermistor to vary signal voltage to PCM according to temperature. PCM applies and monitors a 5-volt reference signal to sensor. When transaxle fluid is cold sensor resistance is high. Thus, PCM will monitor a high signal voltage. As transaxle fluid warms, sensor resistance becomes less and voltage drops. At normal operating temperature of 68-194°F (20-90°C) transaxle temperature signal will measure about 2-4 volts.

Code P0712 will set when the following conditions are present

1. Engine run time is over 2 minutes.
2. Transaxle temperature sensor signal indicates a temperature less than about -40°F (-40°C).
3. Above conditions for over 1.6 second.

Note. Test numbers refer to numbers on diagnostic chart.

1. Determines if conditions necessary to set Code P0712 exist.
2. Simulates conditions to set Code P0713. If PCM recognizes low signal voltage and sets Code P0713, wiring and PCM are okay.
3. Determines if transaxle fluid temperature sensor signal circuit is open. There should be 5 volts present at sensor connector.

Scheme 74

Scheme 75

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside insulation. Check for

Inspect PCM harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.

Monitor scan tester while moving related connectors and wiring harness. If failure is induced, scan data will change from low to high, or high to low. This may assist in isolating malfunction.

Shifted Sensor

See TEMPERATURE-TO-RESISTANCE VALUES table to test sensor at various temperature levels to evaluate possibility of a shifted sensor which may result in driveability complaints.

1. A faulty connection, or an open in sensor circuits will cause Code P0117 to set.

TEMPERATURE-TO-RESISTANCE VALUES

Control module applies and monitors a voltage signal to sensor. 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 2-4 volts.

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

1. Code P0712 indicates control module has seen high resistance in transaxle temperature sensor circuit. This checks if conditions for Code P0712 still exist.
2. Simulates conditions for Code P0713. If control module recognizes low voltage signal, control module and wiring are okay.
3. Determines if sensor signal circuit is open. There should be 5 volts present at connector.

Scheme 76

After 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.

TEMPERATURE-TO-RESISTANCE VALUES

Transaxle temperature sensor uses a thermistor to vary signal voltage to PCM according to temperature. PCM applies and monitors a 5-volt reference signal to sensor. When transaxle fluid is cold sensor resistance is high. Thus, PCM will monitor a high signal voltage. As transaxle fluid warms, sensor resistance becomes less and voltage drops. At normal operating temperature of 68-194°F (20-90°C) transaxle temperature signal will measure about 2-4 volts.

Code P0713 will set when the following conditions are present

1. Engine run time is over one minute.
2. Transaxle temperature sensor signal indicates a temperature greater than 284°F (140°C).
3. All conditions exist for over 1.6 seconds.

Note. Test numbers refer to numbers on diagnostic chart.

1. Determines if conditions necessary to set Code P0713 exist.
2. This test determines if input circuit is shorted to ground which will cause conditions necessary for Code P0713.

Scheme 77

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside insulation. Check for

Inspect PCM harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.

Monitor scan tester while moving related connectors and wiring harness. If failure is induced, scan data will change from low to high, or high to low. This may assist in isolating malfunction.

See TEMPERATURE-TO-RESISTANCE VALUES table to test sensor at various temperature levels to evaluate possibility of a shifted (mis-scaled) sensor which may result in driveability complaints.

TEMPERATURE-TO-RESISTANCE VALUES

Control module applies and monitors a voltage signal to sensor. 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 2-4 volts.

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

1. Code P0713 indicates control module has seen low resistance in transaxle temperature sensor circuit. This checks if conditions for code still exist.
2. This test determines if coolant sensor signal circuit is grounded.

After 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.

TEMPERATURE-TO-RESISTANCE VALUES

The Torque Converter Clutch (TCC) eliminates loss of power to torque converter when cruise control is engaged. This allows convenience of automatic and fuel economy of a manual transaxle. The main components of system are 2 PCM controlled solenoids located inside transaxle.

TCC is applied when TCC apply solenoid coil is activated (on) resulting in a straight through mechanical coupling from engine to wheels. TCC is released when TCC apply solenoid coil is deactivated (off) allowing torque converter to operate in conventional manner (fluid coupling between engine and transaxle).

TCC PWM solenoid is used to vary hydraulic pressure to converter clutch regulator valve, allowing a smoother engagement of converter clutch.

Code P0740 will set when the following conditions are present.

1. TP sensor throttle angle greater than 10 percent.
2. Vehicle is in 3rd or 4th gear.
3. VSS signal greater than 35 MPH for a 10 second minimum.
4. TCC is commanded on by PCM.
5. Engine RPM/vehicle speed ratio indicates TCC is not locked.
6. All conditions exist for over 10 seconds.

Note. Test numbers refer to numbers on diagnostic chart.

1. Determines whether fault is caused by a bad solenoid or control circuit.
2. Checks availability of battery voltage.
3. Checks PCM's ability to pulse PWM solenoid on and off.

Scheme 78

Scan tester only indicates when PCM has commanded TCC driver on, this does not confirm that TCC is actually engaged. Road test vehicle to determine if TCC is properly functioning. Engine RPM should decrease when tester indicates TCC has been turned on. If diagnosis indicates all electrical circuits and components are okay, check for hydraulic and mechanical problems.

Control module monitors difference between engine speed and transaxle input shaft speed. With selector in D3 or D4 (indicated gear 3 or 4) and TCC 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 and, brake not applied, TCC is commanded by control module 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. Checks if fault is caused by a bad solenoid or control circuit.
2. Tests fuse, brake switch, battery power circuits to transaxle connector.
3. Checks control module's ability to pulse PWM solenoid.

Check all connections to transaxle pass-through connector. An open in 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.

SOLENOID TEMPERATURE-TO-RESISTANCE VALUES

The 4T60-E is an electronically shifted transaxle. Within transaxle are 4 solenoids for shift and TCC control. Solenoid "A" is energized for 1st and 4th gear operation. Solenoid "B" is energized for 1st gear as well as 2nd gear operations. The other 2 solenoids are for TCC operation. This diagnostic chart deals with shift control solenoids only.

When ignition is on, both solenoids "A" and "B" receive 12 volts. PCM will ground "A" and "B" circuits for 1st gear until a shift to 2nd gear is commanded. When vehicle speed and TP sensor reach calibrated values, PCM will turn off ground for solenoid "A" and 2nd gear is engaged. Further increase in vehicle speed will cause PCM to turn off ground for solenoid "B", engaging 3rd gear. In 3rd gear, both solenoids are de-energized. In 4th gear, only solenoid "A" is energized.

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

Code P0755 will set when the following conditions are present.

1. Shift "B" is failed in off position, causing transaxle to be in 4th gear and

Desired gear is 1st.

Throttle angle is greater than 3 percent.

VSS is greater than 5 MPH.

Codes P0122, P0123, P0501 or P0502 are not set.

Engine speed-to-vehicle speed does not indicate 1st gear.

Conditions exist for 3.5 seconds.

Or

1. Shift "B" is failed in on position, causing transaxle to be in 1st gear and

Desired gear is 4th.

PRNDL is in 3rd 0r 4th.

Throttle angle is greater than 10 percent.

Codes P0122, P0123 or P0705 are not set.

Engine speed-to-vehicle speed does not indicate 4th gear

(LV8 less than 80).

Conditions exist for 2 seconds.

Scheme 79

The 4T60-E is an electronically shifted transaxle. Within transaxle are 4 solenoids for shift and TCC control. Solenoid "A" is energized for 1st and 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 ignition is turned on, both solenoids "A" and "B" receive battery voltage. Control module will ground both solenoid drivers for 1st gear until a shift to 2nd gear is commanded. When vehicle speed and TPS reach calibrated values, control module will turn off ground for solenoid "A" and 2nd gear is engaged. Further increase in vehicle speed will cause control module to turn off ground for solenoid "B", engaging 3rd gear. When appropriate speed is reached, control module 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 PRNDL inputs indicate manual low has been selected, control module will keep both solenoids "A" and "B" energized until about 5400 RPM, when control module will force a shift by de-energizing solenoid "A". Manual 2nd and manual 3rd are controlled hydraulically within transaxle. Code P0755 will not cause "SERVICE ENGINE SOON" light to illuminate.

Action Taken

When Code P0755 is set, 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 fault goes away, normal operation will be available for balance of key cycle.

Scheme 80

SOLENOID TEMPERATURE-TO-RESISTANCE VALUES

Stepper motor cruise system differs from up integrated (PCM-controlled) cruise system previously used in that it is a stand-alone system. PCM still retains ability to disable cruise if conditions are detected which would make cruise control operation undesirable. PCM may inhibit cruise control if the following conditions are present.

1. Engine not running long enough for cruise control operation.
2. Codes P0705 or P1630 set.
3. Engine speed too high or too low.
4. Vehicle speed too high or too low.
5. Transaxle range input indicates Park, Neutral, Low or Reverse gear selected.

If PCM detects any of these conditions, it will interrupt ground at cruise status signal circuit to request that cruise control disengage.

Code P1550 will set when the following condition is present.

1. Cruise status signal circuit indicates an open or a short to voltage while cruise is engaged and vehicle speed is less than 7 MPH.

Note. Test numbers refer to numbers on diagnostic chart.

1. Ensures PCM is detecting a current fault.
2. This ensures cruise status circuit is not open or grounded, or shorted to voltage, and status circuit is being switched on and off by SMCC module.

Scheme 81

Scheme 82

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside insulation. Check for

Inspect PCM harness for open or short to voltage in status circuit, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection and damaged harness.

Observe SMCC status on scan tester while moving related connectors and wiring harness with engine running. If failure is induced, SMCC status display will change to engaged. This may assist in isolating location of malfunction.

1. On 3.1L, SMCC is a stand-alone system, once software has seen a valid cruise engagement, it has learned cruise is on vehicle.

Stepper motor cruise system differs from integrated (PCM-controlled) cruise system previously used in that it is a stand-alone system. PCM still retains ability to disable cruise if conditions are detected which would make cruise control operation undesirable. PCM may inhibit cruise control if the following conditions are present.

1. Engine not running long enough for cruise control operation.
2. Codes P0705 or P1630 set.
3. Engine speed too high or too low.
4. Vehicle speed too high or too low.
5. Transaxle range input indicates Park, Neutral, Low or Reverse gear selected.

If PCM detects any of these conditions, it will interrupt ground at cruise inhibit signal circuit to request that cruise control disengage.

Note. Test numbers refer to numbers on diagnostic chart.

1. Ensures PCM is detecting a current fault.
2. Ensures cruise status circuit is not open or grounded, or shorted to voltage, and proper voltage is being supplied by SMCC module.

Scheme 83

Scheme 84

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside insulation. Check for

Inspect PCM harness for open or short to voltage in status circuit, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection and damaged harness.

Observe SMCC status on scan tester while moving related connectors and wiring harness with engine running. If failure is induced, SMCC status display will change to engaged. This may assist in isolating location of malfunction.

Stepper motor cruise system differs from up integrated (PCM-controlled) cruise system previously used in that it is a stand-alone system. PCM still retains ability to disable cruise if conditions are detected which would make cruise control operation undesirable. PCM may inhibit cruise control if the following conditions are present.

1. Engine not running long enough for cruise control operation.
2. Codes P0705 or P1630 set.
3. Engine speed too high or too low.
4. Vehicle speed too high or too low.
5. Transaxle range input indicates Park, Neutral, Low or Reverse gear selected.

If PCM detects any of these conditions, it will interrupt ground at cruise inhibit signal circuit to request that cruise control disengage.

Note. Test numbers refer to numbers on diagnostic chart.

1. Ensures PCM is detecting a current fault.
2. Ensures cruise status circuit is not open or grounded, or shorted to voltage, and proper voltage is being supplied by SMCC II module.
3. Checks circuit for short to ground.

Scheme 85

Scheme 86

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside insulation. Check for

Inspect PCM harness for open or short to voltage in status circuit, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.

Observe SMCC status on scan tester while moving related connectors and wiring harness with engine running. If failure is induced, SMCC status display will change to engaged. This may assist in isolating location of malfunction.

PCM is used to control several components as shown in wiring schematic. PCM controls these devises through use of a Quad-Driver Module (QDM). When PCM is commanding a component on, voltage potential of output circuit will be low (near zero volt). When PCM is commanding output circuit to a component off, voltage potential of circuit will be high (near battery voltage). Primary function of QDM is to supply ground for component being controlled.

Each QDM has a fault line which is monitored by PCM. Fault line signal is available on data stream for scan tool test equipment display on Tech 1. PCM will compare voltage at QDM based on accepted values of fault line. If QDM "A" fault detection circuit senses a voltage other than accepted value, fault line will go from a low signal on data stream to a high signal and Code P1640 will set. Code P1640 will set when the following conditions are present.

1. Engine is running.
2. PCM detects an improper voltage level on a circuit connected to QDM "A".
3. Above conditions met for 5 seconds.
4. If brake is applied, QDM "A" ignores fault.

QDM "A" controls EVAP canister solenoid, fan No. 2 and TCC. PCM will illuminate Malfunction Indicator Light (MIL).

Note. Test numbers refer to numbers on diagnostic chart.

1. If QDM related code is stored, diagnose that code first. Repair made to related code will repair Code P1640 also.
2. Determines which QDM "A" control device has failed.

Scheme 87

Scheme 88

Monitor voltage at each QDM terminal while moving related harness connectors, including PCM harness. If failure is induced, voltage will change. This may assist in isolating an intermittent condition. Check for bent pins at PCM and PCM connector terminals. If code reoccurs with no apparent connector problem, replace PCM. PCM is protected by an internal circuit breaker. PCM replacement is not necessary after repairing QDM "A" quad-driver controlled circuit or component.

PCM is used to control several components as shown in wiring schematic. PCM controls these devises through use of a Quad-Driver Module (QDM). When PCM is commanding a component on, voltage potential of output circuit will be low (near zero volt). When PCM is commanding output circuit to a component off, voltage potential of circuit will be high (near battery voltage). Primary function of QDM is to supply ground for component being controlled.

Each QDM has a fault line which is monitored by PCM. Fault line signal is available on data stream for scan tool test equipment display on Tech 1. PCM will compare voltage at QDM based on accepted values of fault line. If QDM "A" fault detection circuit senses a voltage other than accepted value, fault line will go from a low signal on data stream to a high signal and Code P1640 will set.

Code P1640 will set when the following conditions are present

1. Engine is running.
2. PCM detects an improper voltage level on a circuit connected to QDM "A".
3. Above conditions met for 5 seconds.

PCM will illuminate Malfunction Indicator Light (MIL).

Note. Test numbers refer to numbers on diagnostic chart.

1. PCM does not know which controlled circuit caused Code P1640. This chart will go through each of circuits to determine which is at fault. If QDM related codes are present, use applicable code chart first.
2. QDM "A" related code will include Code P0740.
3. QDM "A" symptoms: Cooling fan No. 2 always on or will not come on at all. Poor driveability due to 100 percent canister purge. TCC does not engage. Low oil light always on.
4. This test will determine if problem is circuit or component.
5. This test will determine which circuit is out of specification.
6. As factory installed PCM is protected with an internal circuit breaker, it is highly unlikely that PCM needs to be replaced.

Scheme 89

Scheme 90

Monitor voltage at each QDM terminal while moving related harness connectors, including PCM harness. If failure is induced, voltage will change. This may assist in isolating an intermittent condition. Check for bent pins at PCM and PCM connector terminals. If code reoccurs with no apparent connector problem, replace PCM.

PCM is used to control several components as shown in wiring schematic. PCM controls these devises through use of a Quad-Driver Module (QDM). When PCM is commanding a component on, voltage potential of output circuit will be low (near zero volt). When PCM is commanding output circuit to a component off, voltage potential of circuit will be high (near battery voltage). Primary function of QDM is to supply ground for component being controlled.

Each QDM has a fault line which is monitored by PCM. Fault line signal is available on data stream for scan tool test equipment display on Tech 1. PCM will compare voltage at QDM based on accepted values of fault line. If QDM No. 1 fault detection circuit senses a voltage other than accepted value, fault line will go from a low signal on data stream to a high signal and Code P1640 will set.

Code P1640 will set when the following conditions are present

1. Engine is running.
2. PCM detects an improper voltage level on a circuit connected to QDM No. 1.
3. Brake not applied.
4. All conditions met for 5 seconds.

PCM will illuminate Malfunction Indicator Light (MIL).

Note. Test numbers refer to numbers on diagnostic chart.

1. If QDM related code is stored, diagnose that code first. Repair made to related code will repair Code P1640 also.
2. If QDM No. 1 symptoms are present, checks on Code P1640 chart should isolate cause of fault.
3. This test will determine which circuit is out of specification.
4. Determines if problem is circuit or component.
5. As factory installed PCM is protected with an internal circuit breaker, it is highly unlikely that PCM needs to be replaced.

Scheme 91

Scheme 92

Scheme 93

Monitor voltage at each QDM terminal while moving related harness connectors, including PCM harness. If failure is induced, voltage will change. This may assist in isolating an intermittent condition. Check for bent pins at PCM and PCM connector terminals. If code reoccurs with no apparent connector problem, replace PCM.

Control module controls several components as shown in wiring schematic. Control module controls these devises through use of a Quad-Driver Module (QDM). When control module is commanding a component on, voltage potential of output circuit will be low (near zero volt). When control module is commanding output circuit to a component off, voltage potential of circuit will be high (near battery voltage). Primary function of QDM is to supply ground for component being controlled.

Each QDM has a fault line which is monitored by control module.Fault line signal is available on data stream for scan tool test equipment display on Tech 1. Control module will compare voltage at QDM based on accepted values of fault line. If QDM No. 1 fault detection circuit senses a voltage other than accepted value, fault line will go from a low signal on data stream to a high signal and Code P1640 will set. Control module will illuminate Malfunction Indicator Light (MIL).

Note. Test numbers refer to numbers on diagnostic chart.

1. If QDM related code is stored, diagnose that code first. Repair made to related code will repair Code P1640 also.
2. If QDM No. 1 symptoms are present, checks on chart should isolate cause of fault.
3. This test will determine which circuit is out of specifications.
4. This test will determine if problem is circuit or component.

Scheme 94

Scheme 95

As factory installed control module is protected with an internal circuit breaker, it is highly unlikely that control module needs to be replaced. Monitor voltage at each related terminal while moving related harness connectors, including control module harness. If failure is induced, voltage will change. This may assist in isolating an intermittent condition. Check for bent pins at control module and control module connector terminals. If code reoccurs with no apparent connector problem, replace control module.

PCM is used to control several components as shown in wiring schematic. PCM controls these devises through use of a Quad-Driver Module (QDM). When PCM is commanding a component on, voltage potential of output circuit will be low (near zero volt). When PCM is commanding output circuit to a component off, voltage potential of circuit will be high (near battery voltage). Primary function of QDM is to supply ground for component being controlled.

Each QDM has a fault line which is monitored by PCM. Fault line signal is available on data stream for scan tool test equipment display on Tech 1. PCM will compare voltage at QDM based on accepted values of fault line. If QDM "B" fault detection circuit senses a voltage other than accepted value, fault line will go from a low signal on data stream to a high signal and Code P1650 will set.

Code P1650 will set when the following conditions are present.

1. Engine is running.
2. PCM detects an improper voltage level on a circuit connected to QDM "B".
3. Conditions are met for 5 seconds.

Note. Test numbers refer to numbers on diagnostic chart.

1) Checks for other codes. If quad-driver related codes are present, use those charts first.

Scheme 96

Scheme 97

Monitor voltage at each QDM terminal while moving related harness connectors, including PCM harness. If failure is induced, voltage will change. This may assist in isolating an intermittent condition. Check for bent pins at PCM and PCM connector terminals. If code reoccurs with no apparent connector problem, replace PCM.

1. PCM is protected by an internal circuit breaker.
2. PCM replacement is not necessary after repairing QDM "B" quad- driver controlled circuit or component.

PCM is used to control several components as shown in wiring schematic. PCM controls these devises through use of a Quad-Driver Module (QDM). When PCM is commanding a component on, voltage potential of output circuit will be low (near zero volt). When PCM is commanding output circuit to a component off, voltage potential of circuit will be high (near battery voltage). Primary function of QDM is to supply ground for component being controlled.

Each QDM has a fault line which is monitored by PCM. Fault line signal is available on data stream for display on Tech 1. PCM will compare voltage at QDM based on accepted values of fault line. If QDM "B" fault detection circuit senses a voltage other than accepted value, fault line will go from a low signal on data stream to a high signal and Code P1650 will set.

Code P1650 will set when the following conditions are present.

1. Engine is running.
2. PCM detects an improper voltage level on a circuit connected to QDM "B".
3. Conditions are met for 5 seconds.

Code P1650 will not illuminate Malfunction Indicator Light (MIL).

Note. Test numbers refer to numbers on diagnostic chart.

1. PCM does not know which controlled circuit caused Code P1650. This chart will go through each circuit to determine which is at fault. If QDM related codes are present, use applicable code chart first.
2. If QDM "B" related symptoms are present, checks on Code P1650 chart should isolate cause of fault. QDM "B" symptoms: Improper shifting. TCC will not apply or TCC harsh engagement. Poor driveability due to EGR constantly on.
3. Determines if problem is circuit or component.
4. As factory installed PCM is protected with an internal circuit breaker, it is highly unlikely that PCM needs to be replaced.

Scheme 98

Scheme 99

Monitor voltage at each terminal shown above while moving related harness connectors, including PCM harness. If failure is induced, voltage will change. This may assist in isolating an intermittent condition. Check for bent pins at PCM and PCM connector terminals. If code reoccurs with no apparent connector problem, replace PCM.

PCM is used to control several components as shown in wiring schematic. PCM controls these devices through use of a Quad-Driver Module (QDM). When PCM is commanding a component on, voltage potential of output circuit will be low (near zero volt). When PCM is commanding output circuit to a component off, voltage potential of circuit will be high (near battery voltage). Primary function of QDM is to supply ground for component being controlled.

Each QDM has a fault line which is monitored by PCM. Fault line signal is available on data stream for scan tool test equipment display on Tech 1. PCM will compare voltage at QDM based on accepted values of fault line. If QDM No. 2 fault detection circuit senses a voltage other than accepted value, fault line will go from a low signal on data stream to a high signal and Code P1650 will set.

Code P1650 will set when the following conditions are present.

1. Engine is running.
2. PCM detects an improper voltage level on a circuit connected to QDM No. 2.
3. Above conditions met for 5 seconds.

Code P1650 will not illuminate Malfunction Indicator Light (MIL).

Note. Test numbers refer to numbers on diagnostic chart.

1. If QDM related code is stored, diagnose that code first. Repair made to related code will repair Code P1650 also.
2. This test will determine which circuit is out of specification.
3. Determines if problem is circuit or component.
4. As factory installed PCM is protected with an internal circuit breaker, it is highly unlikely that PCM needs to be replaced.

Scheme 100

Scheme 101

Scheme 102

Monitor voltage at each terminal shown above while moving related harness connectors, including PCM harness. If failure is induced, voltage will change. This may assist in isolating an intermittent condition. Check for bent pins at PCM and PCM connector terminals. If code reoccurs with no apparent connector problem, replace PCM.

Control module is used to control several components as shown in wiring schematic. control module controls these devices through use of a Quad-Driver Module (QDM). When control module is commanding a component on, voltage potential of output circuit will be low (near zero volt). When control module is commanding output circuit to a component off, voltage potential of circuit will be high (near battery voltage). Primary function of QDM is to supply ground for component being controlled.

Each QDM has a fault line which is monitored by control module. Fault line signal is available on data stream for scan tool test equipment display on Tech 1. Control module will compare voltage at QDM based on accepted values of fault line. If QDM No. 2 fault detection circuit senses a voltage other than accepted value, fault line will go from a low signal on data stream to a high signal and Code P1650 will set. Code P1650 will not illuminate Malfunction Indicator Light (MIL).

Note. Test numbers refer to numbers on diagnostic chart.

1. If QDM related code is stored, diagnose that code first. Repair made to related code will repair Code P1650 also.
2. This test will determine which circuit is out of specifications.
3. This test will determine if problem is circuit or component.
4. As factory installed control module is protected with an internal circuit breaker, it is highly unlikely that control module needs to be replaced.

Scheme 103

Monitor voltage at each terminal shown above while moving related harness connectors, including control module harness. If failure is induced, voltage will change. This may assist in isolating an intermittent condition. Check for bent pins at control module and control module connector terminals. If code reoccurs with no apparent connector problem, replace control module.

ELECTRONIC SELF-DIAGNOSTICS (CADILLAC)

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, Malfunction Indicator Light (MIL) will light.

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 trouble codes may be retrieved from PCM memory. DTCs may be retrieved through the instrument panel.

Note. For complete PCM testing and diagnosis, see appropriate article in the ENGINE PERFORMANCE section.

RETRIEVING CODES

Note. Vehicle is capable of displaying trouble codes and computer data on instrument panel. Information is similar to what a scan tool can provide. Use the following information to access transaxle-related trouble codes and to erase them from computer memory. If available, a bidirectional scan tool (Tech 1) can also be used on these vehicles.

In order to access and control PCM self-diagnostic features, 2 electronic components are used: Drivers Information Center (DIC) and Electronic Climate Control Panel (ECCP). (Scheme 104) SERVICE MODE for diagnostic information incorporates odometer/trip odometer as Driver Information Center (DIC) display. When a malfunction is sensed by PCM, MIL will glow on DIC and stay on (with engine running) until code is cleared from PCM.

ECCP becomes controller by which to enter and access self-diagnostics. By pressing appropriate buttons on ECCP, data messages can be sent to PCM, requesting specific diagnostic features. This process allows PCM to transfer any of its available diagnostic information to instrument panel DIC display during service mode operation.

PCM STATUS LIGHTS

While in SYSTEM LEVEL of DIAGNOSTIC SERVICE MODE, mode indicators on ECCP are used to indicate status of certain operating modes. Different modes of operation are indicated by status light being on or off. Following is a description of various status lights.

AUTO A/C Status Indicator

This indicator is used to signify operating mode of PCM. If AUTO is on, PCM is in closed loop. If AUTO is off, PCM is in open loop.

AUTO Fan Status Indicator

This displays status of Park/Neutral switch. When Park/Neutral switch is closed, AUTO fan symbol is on. When Park/Neutral switch is open, AUTO fan symbol is off.

ECON Status Indicator

This displays status of transaxle shift solenoid "B". When ECON is on, transaxle shift solenoid "B" is energized. When ECON is off, transaxle shift solenoid "B" is not energized.

"E" Temperature Status Indicator

This displays status of shift adapt status. When the "E" ..symbol is on, transaxle shift adapts are disabled. When the "E" ..symbol is off, transaxle shift adapts are enabled.

DEFOG Status Indicator

This displays status of transaxle shift solenoid "A". When DEFOG is on, transaxle shift solenoid "A" is energized. When DEFOG is off, transaxle shift solenoid "A" is not energized.

Front Defogger Status Indicator

This indicator is used for A/C clutch command. (Scheme 104) Light should only be on when A/C clutch is engaged.

LO Fan Speed Status Indicator

This indicator is used to indicate status of the throttle position switch. When the throttle position switch is closed, the LO fan symbol is on. When the throttle position switch is open, the LO fan symbol is off.

Rear Defogger Status Indicator

This indicator is used for Torque Converter Clutch (TCC). (Scheme 104) Light only indicates TCC solenoid status requested by PCM; actual operation depends on condition of TCC system.

ENTERING SELF-DIAGNOSTICS

1. Turn ignition switch on. Simultaneously depress OFF and WARMER buttons on Electronic Climate Control Panel (ECCP). (Scheme 104) Continue to depress OFF and WARMER buttons until all segments and bulbs of the DIC and ECCP illuminate.
2. When all segments are lit, system has entered self-diagnostic mode. Release OFF and WARMER button. If all segments of DIC and ECCP glow, go to step 4.
3. Failure of any segment to glow may result in inaccurate test results. All inoperative segments of display must be made to operate before proceeding with self-diagnostic procedures.
4. Powertrain Control Module (PCM) trouble codes are automatically displayed after system enters self-diagnostics. Trouble codes (3-digit) appear in numerical order and are prefixed with letter "P". If no PCM trouble codes are stored, NO PCM CODES message will be displayed.
5. All PCM trouble codes are followed by letter "C" or "H". Letter "C" stands for current and indicates fault presently exists. Letter "H" stands for history and indicates system failure was not present during last key cycle, but was present during one of previous 50 key cycles. For example: Code P024H is PCM Code P024, set in response to a malfunction that occurred in the past (history).

Note. After all trouble codes have been displayed, depressing OFF button on ECCP will activate a repeat of trouble code display.

Scheme 104

Note. DTCs may appear on DIC related to Instrument Panel Cluster (IPC), Supplemental Inflatable Restraint (SIR), A/C Programmer (ACP) or Traction Control System (TCS). For complete information related to these systems, see appropriate article in the ENGINE PERFORMANCE section.

Note. If no codes are present or communication link between a component and ICP is not operating, a NO X DATA message will be displayed, indicating ICP could not communicate with the particular component (X = the particular component).

PCM TROUBLE CODES (CADILLAC)

Entering PCM Data Parameters Display

PCM data parameters (on-line data value) display allows technician to compare present operating specifications of malfunctioning vehicle with specifications of a known good vehicle.

1. With "PCM" displayed on DIC, depress and release HI button on ECCP. This will switch display from "PCM" to "DATA", signaling start of available PCM data.
2. Several types of tests are available. To select different tests, press and release LO button. With "INPUTS" displayed, press and release HI button. Data input parameter displays are prefixed with letters "P I".
3. To advance system to a higher numbered data parameters display, depress HI button on ECCP. To return to a lower numbered data parameters display, depress LO button on ECCP. Stop data parameter display at the one mentioned in the appropriate trouble code test chart.
4. To exit data parameter series at any time and return to "PCM", press and release OFF button 3 times or complete procedures for clearing PCM or ICP trouble codes. See «CLEARING TROUBLE CODES»(/buick/lesabre/vii-1992-1999/remont/automatic-trans/#diagnosis-4t60-e__clearing-trouble-codes) under «ELECTRONIC SELF-DIAGNOSTICS (CADILLAC)»(/buick/lesabre/vii-1992-1999/remont/automatic-trans/#diagnosis-4t60-e__electronic-self-diagnostics-cadillac) .

CLEARING CODES

To clear codes, depress LO button on ECCP 4 times or until ECCP displays PCM CLEAR CODES. Press HI button on ECCP. PCM will clear codes within 3 seconds. Press LO button on ECCP to return to PCM DATA display. If ignition switch is turned to OFF position, trouble codes are not erased.

EXITING SELF-DIAGNOSTICS

To exit self-diagnostics and return to normal system operation, press AUTO or DEFOG button ECCP, press RESET button on DIC, or turn ignition off. Trouble codes will not be cleared by exiting self-diagnostics.

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 ENGINE PERFORMANCE in appropriate MITCHELL manual.

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

PCM monitors ignition voltage on circuit No. 539 to PCM. Code P016 sets when system voltage drops to less than 10 volts or increases to greater than 16 volts with engine running at greater than 500 RPM. If ignition voltage goes to zero volt (open circuit), engine will not run since PCM does not have ignition signal.

Monitor Condition

Engine speed at 500 RPM or greater.

Ignition voltage less than 10 volts or more than 16 volts for 5.3 seconds.

PCM turns on MIL. PCM disables EVAP canister purge system, cruise control and TCC solenoid. PCM disables EGR solenoid and long term fuel trim.

Note. Test numbers refer to numbers on diagnostic chart.

1. Checks PCM data for parameter PD10. If voltage is 16 volts or greater, generator in not controlling voltage.
2. Checks for proper charging system operation.
3. Checks for proper charging system regulation with no electrical loads on generator.

Scheme 105

Scheme 106

Note On Intermittents

Code P016 will be stored as history code if battery charge was low. Load test battery and check for proper operation of charging system. Check for loose battery connection at starter motor and loose connection at generator.

TP sensor is a potentiometer. A 5-volt reference is provided on circuit No. 474 and ground is provided on circuit No. 808. TP sensor signal circuit No. 417 varies between ground and 5 volts based on throttle plate position. At low throttle angle, TP sensor signal voltage is low. PCM uses TP sensor information to determine idle, WOT, deceleration leanness and acceleration enrichment. Code P021 sets when PCM detects a TP sensor signal that is too high.

Monitor Conditions

Engine speed 0-6375 RPM.

TP sensor value greater than or equal to 87 degrees for 0.1 second.

PCM turns on MIL and disables TCC. PCM sets TP sensor equal to 13 degrees when throttle position switch is open and 6 degrees when throttle position switch is closed. PCM disables 3rd and 4th gears.

Note. Test numbers refer to numbers on diagnostic chart.

1. If TP sensor or wiring is shorted, data parameter PD01 will read 87 degrees or greater.
2. Check for shorted TP sensor or wiring. If data value stays greater than -3 degrees with TP sensor and PCM. An open in circuit No. 808 will cause TP sensor signal to be always high whenever TP sensor is connected.
3. Checks for an open or short to power in circuit No. 474.

Scheme 107

Scheme 108

TP sensor is a potentiometer. A 5-volt reference is provided on circuit No. 474 and ground is provided on circuit No. 808. TP sensor signal circuit No. 417 varies between ground and 5 volts based on throttle plate position. At low throttle angle, TP sensor signal voltage is low. PCM uses TP sensor information to determine idle, WOT, deceleration leanness and acceleration enrichment. Code P022 sets when PCM detects a TP sensor signal that is too low.

Engine speed 600 RPM or greater.

TP sensor value less than or equal to -5 degrees for 0.1 second.

PCM turns on MIL and disables TCC. PCM sets TP sensor equal to 13 degrees when throttle position switch is open and 6 degrees when throttle position switch is closed. PCM disables 3rd and 4th gears.

Note. Test numbers refer to numbers on diagnostic chart.

1. If Code P032 is present, check circuit No. 474 for open or short to ground. TP sensor and MAP sensor share 5-volt signal.
2. With TP sensor or wiring open, PCM data parameter PD01 will read -5 or less.
3. Checks for open TP sensor or wiring. If data value stays less than 80 with TP sensor terminals "A" and "C" jumpered together, problem is in wiring.
4. Voltage should be greater than 0.5 volt if circuit No. 474 is not open or shorted to ground.
5. Checks if circuit No. 474 is open, not open or shorted to ground.
6. Checks if signal is reaching PCM. If signal is reaching PCM, then fault is with PCM.

Scheme 109

VSS is a permanent magnet pulse generator mounted in transaxle. PCM receives unbuffered speed information from VSS. Code P024 sets if PCM detects vehicle speed of zero MPH when engine RPM and TP sensor indicate that vehicle is moving. To avoid any erratic cruise control operation due to an intermittent problem, cruise control system is disabled for the entire ignition cycle.

Codes P021, P022, P026 and P027 not set. Transaxle in Drive or Reverse. Brakes not applied, throttle position switch open, throttle angle at 17.3 degrees or greater, and engine speed at 1400 RPM or greater.

Vehicle speed at zero MPH for 3.3 seconds.

PCM turns on MIL, and disables Torque Converter Clutch (TCC) and cruise control for the entire ignition cycle. PCM disables 3rd and 4th gears.

Note. Test number refers to number on diagnostic chart.

1. If Code P024 is current, fault is present and can directly be diagnosed. If Code P024 is stored as history, fault is intermittent. Use Code P075 to diagnose.
2. When spun by hand, VSS will generate a frequency of greater than zero hertz. If it does, PCM may be faulty. If it does not, check for opens and shorts in wires/sensor.

Scheme 110

Scheme 111

Check for Electromagnetic Interference (EMI) induced on circuits No. 400 and 401 by running them close to spark plug wires or high power transmitters (like mobile radios) operating in vicinity.

This code test monitors engine RPM and vehicle speed, and compares them. PCM will set code when engine speed exceeds fault value for a particular vehicle speed. This code can set due to an electrical problem, or slippage of TCC or transaxle clutches. If a TCC or transaxle clutch failure has occurred, failure is more likely to be observed under high road load (high MAP) conditions. Use code snapshot data to confirm failure.

Codes P026, P027, P031, P032 and P034 not set, PCM commanding 4th gear and engine speed at 3100 RPM or less. Engine in closed loop and MAP between 29-80 kPa. TCC commanded on and brake off, and TCC mod solenoid at 100 percent duty cycle. Throttle position switch open.

Code P039 sets when engine RPM is greater than RPM fault. See TCC APPLIED TEST table.

TCC APPLIED TEST

PCM turns on MIL and disables TCC for entire ignition cycle.

Test Description (1 OF 5)

Note. Test number refers to number on diagnostic chart.

Scheme 112

Scheme 113

1. Checks electrical operation of transaxle using Transmission Test Box (J 38791).

Test Description (2 OF 5)

Note. Test numbers refer to numbers on diagnostic chart.

Scheme 114

1. Checks TCC brake switch or wiring fault. PCM input PI71 should cycle from HI to LO if no problem exists. If PI71 does not cycle, and test box LED is off, check test box for proper connection. See PCM VOLTAGE CHART.
2. To adjust brake switch, first fully seat switch in its retainer, then pull up on brake pedal. PCM VOLTAGE CHART PCM Terminal Condition Voltage 1C4 Brake Applied 0-0.3 1C4 Brake Released Battery

Test Description (3 OF 5)

Note. Test numbers refer to numbers on diagnostic chart.

Scheme 115

1. Checks for TCC modulation and TCC apply solenoid, or wiring fault. See PCM VOLTAGE CHART. PCM VOLTAGE CHART PCM Terminal Condition Voltage 3F6 TCC Apply On 0-0.3 3F6 TCC Apply Off Battery 3F5 TCC Mod. On 0-0.3 3F5 TCC Mod. Off Battery

Test Description (4 OF 5)

Note. Test numbers refer to numbers on diagnostic chart.

Scheme 116

1. Checks for faults in shift solenoids "A" and "B" or wiring faults. See PCM VOLTAGE CHART. PCM VOLTAGE CHART PCM Terminal Condition Voltage 3E10 Shift Sol. "A" On 0-0.3 3E10 Shift Sol. "A" Off Battery 3E4 Shift Sol. "B" Off 0-0.3 3E4 Shift Sol. "B" Off Battery

Test Description (5 OF 5)

Note. Test numbers refer to numbers on diagnostic chart.

1. This stall test checks for TCC apply.
2. Checks for TCC modulation operation.
3. Code setting with normal TCC operation may indicate possible transaxle clutch slippage, usually during high road load (high MAP) conditions. Use code snapshot data to confirm condition. Check transaxle for signs of 4th clutch slippage.

Scheme 117

Note On "No TCC Apply"

TCC not applying can be caused by faulty TCC solenoid and/or "O" ring, TCC apply valve, TCC solenoid screen, turbine shaft and/or seals or faulty torque converter. Perform transaxle diagnosis.

Note on "TCC Applies W/Maximum Pressure/Harsh Apply"

Harsh application of TCC or TCC at maximum pressure, can be caused by faulty TCC MOD solenoid and/or "O" ring or a faulty converter clutch regulator valve. Perform transaxle diagnosis.

Transaxle temperature sensor is a thermistor whose resistance varies based on its temperature. As sensor temperature increases, resistance decreases. A high transaxle temperature will result in a low signal voltage on circuit No. 585. Code P057 sets when PCM see transaxle temperature sensor reading of 298°F (148°C) or greater (0.8 volt or less).

Tested continuously.

Transaxle temperature sensor value is 298°F (148°C) or greater for 5 seconds.

PCM turns on MIL. PCM substitutes engine coolant temperature value for transaxle temperature until engine coolant temperature reaches 221°F (105°C), then transaxle will be set to hot mode operation.

Note. Test numbers refer to numbers on diagnostic chart.

1. If transaxle temperature sensor is shorted, PCM data PD19 should read 298°F (148°C) or greater. If parameter does not show this, then sensor and wiring are okay. Fault is intermittent.
2. Checks circuit No. 585 for short. If parameter value stays at -18°F (-28°C) or greater with transaxle connector unplugged, check for short in circuit No. 585, PCM terminal 3F12 or transaxle connector terminal "F".
3. Checks circuits No. 585 for short to ground inside transaxle. If wiring is okay, replace shorted transaxle temperature sensor.

Scheme 118

Scheme 119

Transaxle temperature sensor is a thermistor whose resistance varies based on its temperature. As sensor temperature increases, resistance decreases. A low transaxle temperature will result in high signal voltage on circuit No. 585. Code P059 sets when PCM sees a transaxle temperature sensor reading of -31°F (-35°C) or less (4.9 volts or greater).

Codes P014, P015 and P024 not set and coolant temperature -13.0°F (-25°C) or greater.

Transaxle temperature sensor -31°F (-35°C) or less for 6 seconds.

PCM turns on MIL. PCM substitutes coolant temperature value for transaxle temperature until coolant temperature reaches 221°F (105°C) then sets transaxle to hot mode operation.

Note. Test numbers refer to numbers on diagnostic chart.

1. With transaxle temperature sensor or wiring open, PCM data PD19 will read -31°F (-35°C) or less. If parameter does not show this, sensor and wiring are okay.
2. Check for open in circuit No. 585 between PCM and transaxle connector. If PCM data PD77 reads 298-303°F (148-151°C) with connector terminal "F" jumpered to ground, circuit No. 585 and PCM are okay.
3. Checks circuit No. 808 for open to PCM terminal 3E11.
4. Checks PCM's ability to recognize low voltage on PCM terminal 3F12 (transaxle temperature sensor input). If grounding PCM terminal 3F12 caused PCM data PD19 to read 298-303°F (148-151°C), check for open in circuit No. 585 between PCM and transaxle connector.
5. Checks for an open transaxle temperature sensor.

Scheme 120

This test monitors MAP and TP sensors. Code P070 will set if MAP value remains constant and TP sensor value changes considerably. Engine operation requires that any large change in throttle angle must be followed by a change in MAP.

Codes P031, P032 and P034 not set. Throttle angle changes more than 3.5 degrees in 12.5 milliseconds (.0125 seconds). Engine not decelerating (MAP drops to 22 kPa or less). Engine not accelerating (MAP is within 7.4 kPa of atmospheric pressure). Engine running.

MAP changes 3 kPa or less in .16 second following a 3.5 degree or greater change in throttle angle.

None.

Note. Test number refers to number on diagnostic chart.

1. Checking Code P070 snapshot value is used to determine if an intermittent low or high voltage caused code to set. An intermittent low voltage can be caused by an open or short to ground in circuit No. 417, an open in circuit No. 474, or a faulty TP sensor. An intermittent high voltage can be caused by an open in circuit No. 808 or a short to voltage on circuit No. 417.

Scheme 121

This test compares vehicle speed to Manifold Absolute Pressure (MAP). Change in MAP must correspond with change in vehicle speed. PCM will ignore test if conditions for engine idle are present. If vehicle speed changes 8 MPH or greater in one second and is not accompanied by a greater than 2 kPa change in MAP, Code P075 will set.

This code will not turn on MIL. This code may be caused by an intermittent open or short to ground or each other on circuit No. 400 and circuit No. 401, an intermittent vehicle speed sensor, or an intermittent terminal contact at PCM terminals 2B9, 2B10 or at vehicle speed sensor.

This code may also be caused by Electromagnetic Interference (EMI) induced on circuit No. 400 or circuit No. 401 by running them along side spark plug wires or high power transmitters, like mobile radios, operating in vicinity, or running the vehicle in gear with wheels off the ground (on a hoist).

Codes P031, P032 and P034 not set, engine running, not at idle, and brakes not applied.

Vehicle speed change of 8 MPH or more in a one-second time period with a corresponding MAP change of 2kPa or less.

None.

Ciruit Description

This test assumes that brake must be applied to bring vehicle to a stop from 30 MPH or greater. If such condition occurs, counter is incremented. When counter reaches 10, Code P090 is set. Counter is reset to zero if a transition of TCC brake switch is detected by PCM before counter reaches 10.

Code P024 not set, engine running and vehicle speed at 30 MPH or greater.

Vehicle speed changes from 30 MPH or greater to zero MPH with no TCC brake switch input, then increment counter. When counter reaches 10, set Code P090.

PCM turns on SERVICE VEHICLE SOON message. PCM disables cruise control.

Note. Test numbers refer to numbers on diagnostic chart.

1. Testing TCC brake switch input to PCM PI71. If input is working correctly, display will change from HI to LO to HI. If display remains HI, check circuit No. 420 and TCC brake switch for short to voltage. If display remains LO, check circuit No. 420 for open or short to ground.
2. Checks for voltage at TCC brake switch terminal "A".
3. Checks circuit No. 741 for a short to ground or a blown fuse D1.
4. Checks circuit No. 741 for an open or circuit No. 420 for a short to ground or a blown fuse D1.
5. Checks circuit No. 420 for an open or a poor connection at PCM.

Scheme 122

This test monitors the park/neutral input from transaxle range switch to PCM (PD72). Transaxle range switch also sends information relative to gear selection to instrument panel cluster (ID41). PCM compares the two decoded signals and if PCM detects a fault in one of the decoded signals or engine starts with no park/neutral input, or if vehicle is in 4th gear and engine speed divided by vehicle speed is between 23 RPM/MPH, and park/neutral input indicates park/neutral Code P091, then Code I027 will set.

Tested continuously.

Park/neutral input and Park/Neutral indication from IPC are not the same, or engine starts with no Park/Neutral input, or PRNDL indication from IPC is illegal, or vehicle is in fourth gear, engine speed divided by vehicle speed is between 23 RPM/MPH and 35 RPM/MPH, and park/neutral input indicates in Park/Neutral.

PCM turns on MIL. PCM disables cruise control.

Scheme 123

Scheme 124

This test checks for unusually large throttle position at low vehicle speed with the brake being applied. Primary purpose of Code P096 is to record snapshot data and alert driver that this condition could damage vehicle drivetrain or create an unsafe condition. Code P096 will set if such a driving condition exists.

Most occurrences of this code will be due to the application of brake and accelerator at the same time. TCC brake switch, transaxle range switch, VSS and TP sensor failures should be caught by other diagnostic codes. If any of the following checks fail, see appropriate code chart for diagnosis.

1. Check operation of brake switch using TCC brake switch input test (PI71).
2. Check operation of TP sensor by monitoring TPS degrees while moving throttle (Codes P021, P022 and P070).
3. Check for correct MPH indication on instrument panel (Code P024).
4. Check operation of transaxle range switch by monitoring AUTO status light while shifting in and out of Park/Neutral (Code P091).

Codes P021, P022 and P024 not set.

Brake applied, transaxle in Drive or Reverse, vehicle speed 5 MPH or less, and throttle position 65 degrees or greater for 12 seconds.

PCM turns on MIL and stays on for 15 seconds after Code P096 becomes history.

ELECTRONIC TESTING

Note. The following procedures check operation of electronic control of 4T60-E transaxle.

Scheme 125

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 125) Connect a bidirectional scan tool or Tech 1 (94-00101 A) to DLC 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 126)
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 127)through (Scheme 129). See appropriate COMPONENT TESTS procedures.

COMPONENT TESTS (WITH TEST BOX)

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

Scheme 126

Scheme 127

Scheme 128

Scheme 129

Scheme 130

COMPONENT TESTS (WITHOUT TEST BOX)

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

Scheme 131

Scheme 132

Scheme 133

Scheme 134

Scheme 135

1995 "A" Body - 3.1L (Century, Cutlass Ciera & Cutlass Cruiser) Schematic. Scheme 136

1995 "C" & "H" Bodies - 3.8L (Bonneville, Eighty-Eight, LeSabre, Ninety-Eight & Park Avenue) Schematic. Scheme 137

1995 "G" Body - 3.8L (Riviera) Schematic. Scheme 138

1995 "L" Body - 3.1L (Beretta & Corsica) Schematic. Scheme 139

1995 "N" Body - 2.3L (Achieva, Grand Am & Skylark) Schematic. Scheme 140

1995 "N" Body - 3.1L (Achieva, Grand Am & Skylark) Schematic. Scheme 141

1995 "U" Body - 3.8L (Lumina APV, Silhouette & Trans Sport) Schematic. Scheme 142

1995 "W" Body - 3.1L (Cutlass Supreme, Grand Prix, Lumina, Monte Carlo & Regal) Schematic. Scheme 143

1995 "W" Body - 3.4L (Cutlass Supreme, Grand Prix, Lumina & Monte Carlo) Schematic. Scheme 144

1995 "W" Body - 3.8L (Regal) Schematic. Scheme 145

See also:
• ELECTRONIC TESTING
• CLEARING TROUBLE CODES
• WIRING DIAGRAMS
• ELECTRONIC SELF-DIAGNOSTICS (CADILLAC)