Automatic Transaxle Diagnosis - 4t40-e (2.4l) Chevrolet Malibu V

INTRODUCTION

The 4T40-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.

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

LIMP-IN MODE

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

PCM

PCM is located below left side of instrument panel, near steering column. On all models, PCM utilizes 2 different colored 80-pin connectors. (Scheme 25) PCM controls ignition, fuel and emission devices related to engine and transaxle upshifts and downshifts.

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

SENSORS & SWITCHES

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

SOLENOIDS

Transaxle is shifted up or down by 2 electric solenoids. Both solenoids are located on valve body. Ignition power is supplied to each solenoid by 10-amp AUTO TRANS fuse located in instrument panel fuse block. For solenoid positions at each selector lever position, see CLUTCH & BAND APPLICATION CHART under ELECTRONIC TESTING.

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

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

CLUTCH & BAND APPLICATION

CLUTCH & BAND APPLICATION CHART

SELF-DIAGNOSTIC SYSTEM

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

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

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

RETRIEVING CODES

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

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

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

TROUBLE CODE DEFINITIONS

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

PCM TROUBLE CODE DEFINITIONS

HARD OR INTERMITTENT TROUBLE CODE DETERMINATION

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

1. Enter diagnostic mode. See «RETRIEVING CODES»(/chevrolet/malibu/v-1996-2000/remont/automatic-trans/#automatic-transaxle-diagnosis-4t40-e-24l__retrieving-codes) . Read and record all stored DTCs. Exit diagnostic mode and clear trouble codes. See «CLEARING TROUBLE CODES»(/chevrolet/malibu/v-1996-2000/remont/automatic-trans/#automatic-transaxle-diagnosis-4t40-e-24l__clearing-trouble-codes) .
2. Apply parking brake and place transaxle in Neutral or Park. Block drive wheels and start engine. MIL should go out. Run warm engine at specified curb idle for 2 minutes and note MIL.
3. If MIL comes on, enter diagnostic mode. Read and record DTCs. This will reveal hard failure codes. DTCs may require a road test to reset hard failure after clearing DTCs. If MIL does not come on, all stored DTCs were intermittent failures.

CLEARING TROUBLE CODES

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

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

ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK

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

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

The OBD System Check determines

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

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

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

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

Diagnostic Aids

DO NOT clear DTCs unless directed by a diagnostic procedure. Clearing DTCs will also clear valuable freeze frame and failure records data. Check for any technical service bulletins related to exhibited symptoms or component operation. Inspect all related wiring and connections at PCM for intermittent malfunction. Check for backed out terminals, improper mating, broken locks, damaged terminals, damage to wiring harness or corrosion.

Diagnostic Tests

Following diagnostic tests are DTC specific. Always perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing any diagnostic procedure. For PCM terminal locations (Scheme 25) See WIRING DIAGRAMS. For engine-related DTCs, see appropriate TESTS W/CODES article in ENGINE PERFORMANCE.

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

DTC P0218: TRANSAXLE FLUID OVERHEATING

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS . For oil circuit identification, see HYDRA-MATIC 4T40-E/4T45-E article in HYDRAULIC DIAGRAMS.

Circuit Description

Transaxle oil pump is constantly circulating fluid through torque converter. Hot fluid leaving converter flows through transaxle cooler lines to oil cooler, located in radiator. Fluid is then routed back to transaxle.

Lube circuit No. 1 is routed through input shaft to lubricate transaxle components in front of transaxle. Lube circuit No. 2 is fed by line pressure at pressure regulator valve. This fluid is routed through oil feed pipes and into forward clutch support. Lube circuit No. 2 provides lubrication to rear of transaxle. DTC P0218 will set when PCM detects a high transaxle fluid temperature for long period of time.

Conditions For Setting DTC P0218

DTC will set under the following conditions

1. When transaxle temperature is more than 260°F (130°C) for 15 minutes.
2. DTCs P0711, P0712 or P0713 (transaxle fluid temp sensor) are not present.

Action Taken By PCM

PCM performs the following if DTC is set

1. Will not light MIL when fault is set.
2. Freezes shift adapts from being updated.
3. DTC P0218 will be stored in PCM history.

Diagnostic Procedure

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Check transaxle fluid level. Fill as necessary. Inspect engine and transaxle cooling system for air flow restrictions or blockage, debris or damaged cooler lines. Repair as necessary, then go to step 4). If no problems are found, go to next step.
3. Check control valve assembly for stuck or leaking pressure regulator valve. Repair as necessary, then go to next step. If valve is okay, inspect oil feed tubes for restriction or leaking seals. Repair as necessary, then go to next step. If tubes are okay, check for torque converter stator damage. Repair as necessary, then go to next step.
4. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0218". Turn ignition switch to ON position for 10 seconds. TFT temperature must be 264°F (129°C) or less for 5 seconds. If DTC P0218 is not present, repair is complete. If DTC P0218 is still present, repeat test.

Question owner for possible vehicle overloading, exceeding trailer towing limit or towing in overdrive.

DTC P0502: VEHICLE SPEED SENSOR CIRCUIT (LOW INPUT)

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS .

Vehicle speed is signaled to PCM by Vehicle Speed Sensor (VSS). Sensor is a Permanent Magnet (PM) generator mounted to transaxle case. PM generator produces an AC voltage as speed sensor rotor teeth pass sensor's magnetic field. AC voltage level increases as speed of vehicle increases. PCM converts AC voltage into digital signal. PCM uses vehicle speed to determine shift timing, TCC apply and release, and gear ratio calculations. DTC P0502 will set when PCM detects a low vehicle output speed when vehicle has high engine speed in drive gear.

Conditions For Setting DTC P0502

DTC will set under the following conditions

1. Transaxle is in drive.
2. DTCs P0107 or P0108 (MAP sensor), P0121, P0122 or P0123 (throttle position sensor) or P1810 (pressure switch assembly) are not present.
3. DTCs P0716 or P0717 (input speed sensor) are not present.
4. DTC P1644 (engine torque) is not present.
5. Throttle position angle is 15-99 percent.
6. MAP is more than 3 psi (20 kPa).
7. Input speed is more than 1000 RPM.
8. Output speed is less than 2 MPH.
9. All conditions are met for 5 seconds.

PCM performs the following if DTC is set

1. Will light MIL after 2 consecutive trips with a failure signal.
2. Freezes shift adapts from being updated.
3. Commands maximum line pressure.
4. Inhibits TCC engagement.
5. Calculates output speed from input speed, engine speed and commanded gear.
6. DTC P0502 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. Raise and support vehicle. CAUTION: To prevent damage to drive axles, support lower control arms in normal horizontal position.
2. Start engine and let idle. Shift gear selector to "D" position. With drive wheels rotating, if transaxle output speed does not increase when wheel speed increases, go to next step. If transaxle output speed increases when wheel speed increases, condition is intermittent. See DIAGNOSTIC AIDS.
3. Turn ignition off. Disconnect both PCM 80-pin connectors. PCM is located under left side of instrument panel, near steering column.
4. On all models, connect DVOM between VSS terminals at appropriate PCM connectors (Purple wire and Yellow wire). See «WIRING DIAGRAMS»(/chevrolet/malibu/v-1996-2000/remont/automatic-trans/#automatic-transaxle-diagnosis-4t40-e-24l) . Set DVOM to AC scale. Turn ignition switch to ON position. DO NOT start engine. Rotate drive wheels and observe DVOM display. If DVOM displays more than .5 volt, replace PCM, then go to step 7). If DVOM displays less than .5 volt, go to next step.
5. Turn ignition off. Set DVOM to ohms while still connected to VSS terminals at PCM connectors. If resistance is 1530-1870 ohms, repair short to ground in Yellow wire, then go to step 7). If wire is okay, go to next step. If resistance is more than 1870 ohms, repair open in Purple wire or Yellow wire, then go to step 7). If wires are okay, replace speed sensor, then go to step 7). If resistance is less than 1530 ohms, disconnect speed sensor connector at transaxle. If resistance is less than 1530 ohms, check for VSS wires shorted together. Repair as necessary, then go to step 7). If resistance is more than 1530 ohms, replace speed sensor, then go to step 7).
6. Reconnect PCM connector(s). Set DVOM to DC volts. Connect DVOM to VSS connector terminals. Turn ignition switch to ON position. DO NOT start engine. If DVOM displays system voltage, repair short to voltage in Yellow wire, then go to next step. If DVOM does not display system voltage, remove speed sensor from transaxle. Check for incorrect speed sensor, sensor damage, excessive air gap between sensor and rotor, rotor damage or incorrect rotor alignment. Inspect for transaxle case damage. Repair or replace components as necessary, then go to next step.
7. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0502". Operate vehicle at more than 2 MPH for 5 seconds. If DTC P0502 is not present, repair is complete. If DTC P0502 is still present, repeat test.

Condition may be intermittent. Check for loose speed sensor mounting or poor sensor connection. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Inspect for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change. Inspect for damaged speed sensor or transaxle rotor teeth. A slipping forward clutch could set DTC P0502.

DTC P0503: VEHICLE SPEED SENSOR CIRCUIT (INTERMITTENT)

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS .

Vehicle speed is signaled to PCM by Vehicle Speed Sensor (VSS). Sensor is a Permanent Magnet (PM) generator mounted to transaxle case. PM generator produces an AC voltage as speed sensor rotor teeth pass sensor's magnetic field. AC voltage level increases as speed of vehicle increases. PCM converts AC voltage into digital signal. PCM uses vehicle speed to determine shift timing, TCC apply and release, and gear ratio calculations. DTC P0503 will set when PCM detects a loss of vehicle speed while vehicle is in motion.

Conditions For Setting DTC P0503

DTC will set under the following conditions

1. Engine is running.
2. Time since gear selector lever change is more than 3 seconds.
3. DTC P1810 (TFP manual valve position switch) is not present.
4. Output speed drops more than 1200 RPM within 4 seconds.

PCM performs the following if DTC is set

1. Will light MIL after 2 consecutive trips with a failure signal.
2. Freezes shift adapts from being updated.
3. Commands maximum line pressure.
4. Calculates output speed from input speed, engine speed and commanded gear.
5. DTC P0503 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. Raise and support vehicle. CAUTION: To prevent damage to drive axles, support lower control arms in normal horizontal position.
2. Start engine and let idle. Shift gear selector to "D" position. With drive wheels rotating, if transaxle output speed does not increase when wheel speed increases, go to next step. If transaxle output speed increases when wheel speed increases, condition is intermittent. See DIAGNOSTIC AIDS.
3. Turn ignition off. Disconnect both PCM 80-pin connectors. PCM is located under left side of instrument panel, near steering column.
4. On all models, connect DVOM between VSS terminals at appropriate PCM connectors (Purple wire and Yellow wire). See «WIRING DIAGRAMS»(/chevrolet/malibu/v-1996-2000/remont/automatic-trans/#automatic-transaxle-diagnosis-4t40-e-24l) . Set DVOM to AC scale. Turn ignition switch to ON position. DO NOT start engine. Rotate drive wheels and observe DVOM display. If DVOM displays more than .5 volt, replace PCM, then go to step 7). If DVOM displays less than .5 volt, go to next step.
5. Turn ignition off. Set DVOM to ohms while still connected to VSS terminals at PCM connectors. If resistance is 1530-1870 ohms, repair short to ground in Yellow wire, then go to step 7). If wire is okay, go to next step. If resistance is more than 1870 ohms, repair open in Purple wire or Yellow wire, then go to step 7). If wires are okay, replace speed sensor, then go to step 7). If resistance is less than 1530 ohms, disconnect speed sensor connector at transaxle. If resistance is less than 1530 ohms, check for VSS wires shorted together. Repair as necessary, then go to step 7). If resistance is more than 1530 ohms, replace speed sensor, then go to step 7).
6. Reconnect PCM connector(s). Set DVOM to DC volts. Connect DVOM to VSS connector terminals. Turn ignition switch to ON position. DO NOT start engine. If DVOM displays system voltage, repair short to voltage is Yellow wire, then go to next step. If DVOM does not display system voltage, remove speed sensor from transaxle. Check for incorrect speed sensor, sensor damage, excessive air gap between sensor and rotor, rotor damage or incorrect rotor alignment. Inspect for transaxle case damage. Repair or replace components as necessary, then go to next step.
7. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0503". Road test vehicle and ensure speed sensor is operating. If DTC P0503 is not present, repair is complete. If DTC P0503 is still present, repeat test.

Condition may be intermittent. Check for loose speed sensor mounting or poor sensor connection. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Inspect for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change. Inspect for damaged speed sensor or transaxle rotor teeth.

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

PERFORMANCE MALFUNCTION

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS .

Transaxle Fluid Temperature (TFT) sensor is a negative coefficient thermistor. When transaxle fluid is cold, sensor resistance is high. As transaxle fluid warms, sensor resistance decreases. PCM monitors TFT circuit. Circuit may be functional but not in normal operating range. DTC P0711 indicates stuck, erratic, intermittent or skewed values, indicating poor system performance. TFT range is -40 to 305°F (-40 to 151°C). DTC P0711 will set when PCM detects an intermittent voltage or no voltage change in TFT sensor circuit.

Conditions For Setting DTC P0711

DTC will set under the following conditions

1. DTCs P0502 or P0503 (vehicle speed sensor) are not present.
2. DTCs P0716 or P0717 (input speed sensor) are not present.
3. Transaxle fluid temperature at start-up is -40 to 70°F (-40 to 21°C).
4. System voltage is 9-16 volts.
5. Engine run time is more than 5 minutes.
6. Vehicle speed is more than 5 MPH for 6 minutes and 49 seconds.
7. TCC slip is more than 300 RPM for 6 minutes and 49 seconds.
8. Engine coolant temperature is more than 158°F (70°C).
9. Engine coolant temperature has changed by more than 90°F (50°C) since start-up.

Failure Criteria

Change in transaxle fluid temperature is less than 2°F (1.5°C) since start-up for one minute and 20 seconds, or change in transaxle fluid temperature is more than 36°F (20°C) within 200 milliseconds, 14 times within 7 seconds.

PCM performs the following if DTC is set

1. Will light MIL after 2 consecutive trips with failure reported.
2. Freezes shift adapts from being updated.
3. Will calculate default transaxle temperature based on engine coolant temperature, manifold air temperature and engine run time.
4. DTC P0711 will be stored in PCM history.

1. Check transaxle fluid level. Fill as needed. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select "TFT sensor" on scan tool. Drive vehicle and observe scan tool for one of the following fail conditions: TFT fluid temperature does not change by more than 2.7°F (1.5°C) in 80 seconds since start-up, or TFT fluid temperature changes by more than 36°F (20°C) within 200 milliseconds, 14 times within 7 seconds (unrealistic change). If either fail condition occurs, go to next step. If neither fail conditions occurs, see DIAGNOSTIC AIDS.
3. If scan tool displays a condition in which TFT fluid temperature does not change by more than 2.7°F (1.5°C) in 80 seconds since start-up, go to step 7). If scan tool does not display this condition, go to next step.
4. Turn ignition off. Disconnect transaxle 20-pin connector. Install Jumper Harness (J-39775) on engine side of transaxle 20-pin connector. Connect a test light between terminals "L" and "M" at transaxle 20-pin connector. (Scheme 24) Turn ignition switch to ON position. DO NOT start engine.
5. While observing scan tool display, wiggle wiring harness between transaxle 20-pin connector and PCM connectors. If TFT fluid temperature changes by more than 36°F (20°C), check for intermittent open or short in wires between transaxle 20-pin connector and PCM. Repair wires as necessary, then go to step 8). If wires are okay, replace PCM, then go to step 8).
6. If TFT fluid temperature does not change by more than 36°F (20°C), check for intermittent open or short in wires between transaxle 20-pin connector and TFT fluid sensor. Repair wires as necessary, then go to step 8). If wires are okay, replace TFT fluid sensor, then go to step 8).
7. Turn ignition off. Disconnect transaxle 20-pin connector. Turn ignition switch to ON position. DO NOT start engine. If scan tool displays a condition in which TFT fluid temperature does not change by more than 2.7°F (1.5°C) in 80 seconds since start-up, replace PCM, then go to next step. If scan tool does not display this condition, replace TFT fluid sensor, then go to next step.
8. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0711". Drive vehicle and ensure TFT fluid temperature changes by more than 4°F (2.25°C) for 5 seconds since start-up, and TFT fluid temperature does not change by more than 36°F (20°C) within 200 milliseconds for at least 11 seconds. If DTC P0711 is not present, repair is complete. If DTC P0711 is still present, repeat test.

Inspect wiring for poor connections at PCM and at transaxle 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Inspect for broken wire inside insulation. Test TFT sensor at various temperature levels to evaluate possibility of a skewed (mis-scaled) sensor. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change. Inspect transaxle wiring harness for transaxle fluid.

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

(LOW INPUT)

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS .

Transaxle Fluid Temperature (TFT) sensor is a thermistor which is part of the Transaxle Fluid Pressure (TFP) manual valve position switch. PCM supplies a 5-volt reference signal to sensor on circuit No. 1227 (Yellow/Black wire). When transaxle fluid is cold, sensor resistance is high and PCM will sense a high signal voltage. As transaxle fluid warms, sensor resistance lowers and PCM senses lower voltage. PCM uses TFT sensor readings to control TCC apply and release, line pressure adjustments and temperature compensated shifts. DTC P0712 will set when PCM detects a continuous short to ground in TFT sensor circuit or TFT sensor.

Conditions For Setting DTC P0712

DTC will set under the following conditions

1. Ignition is on.
2. TFT voltage is less than .33 volt for 10 seconds.

PCM performs the following if DTC is set

1. Will not light MIL when fault is set.
2. Freezes shift adapts from being updated.
3. Will calculate transaxle temperature based on engine coolant temperature, manifold air temperature and engine run time.
4. DTC P0712 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select "TFT sensor" on scan tool. If scan tool displays transaxle fluid temperature at 304°F (151°C), go to next step. If scan tool does not display transaxle fluid temperature at 304°F (151°C), see DIAGNOSTIC AIDS.
3. Turn ignition off. Disconnect transaxle 20-pin connector. Turn ignition switch to ON position. If scan tool displays transaxle fluid temperature at -40°F (-40°C), go to next step. If scan tool does not display transaxle fluid temperature at -40°F (-40°C), check for short to ground in Yellow/Black wire between transaxle 20-pin connector (PCM side) and PCM. Repair wire as necessary, then go to step 6). If wire is okay, replace PCM, then go to step 6).
4. Install Jumper Harness (J-39775) to transaxle side of 20-pin connector. Connect ohmmeter between terminals "L" and "M" (Yellow/Black wire and Black wire) of 20-pin connector. (Scheme 24) If resistance is 3106-3923 ohms at 68°F (20°C) and 164-190 ohms at 212°F (100°C), replace PCM then go to step 6).
5. If resistance is not 3106-3923 ohms at 68°F (20°C) and 164-190 ohms at 212°F (100°C), check for short to ground in Yellow/Black wire between transaxle 20-pin connector and TFT sensor connector. Repair wire as necessary, then go to next step. If wire is okay, replace TFP manual valve position switch, then go to next step.
6. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0712". Turn ignition switch to ON position for more than 3 seconds. TFT signal voltage must be more than.33 volts. If DTC P0712 is not present, repair is complete. If DTC P0712 is still present, repeat test.

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

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

(HIGH INPUT)

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS .

Transaxle Fluid Temperature (TFT) sensor is a thermistor which is part of the Transaxle Fluid Pressure (TFP) manual valve position switch. PCM supplies a 5 volt reference signal to sensor on circuit No. 1227 (Yellow/Black wire). When transaxle fluid is cold, sensor resistance is high and PCM will sense a high signal voltage. As transaxle fluid warms, sensor resistance lowers and PCM senses lower voltage. PCM uses TFT sensor readings to control TCC apply and release, line pressure adjustments and temperature compensated shifts. DTC P0713 will set when PCM detects a continuous open or short to voltage in TFT sensor circuit or TFT sensor.

Conditions For Setting DTC P0713

DTC will set under the following conditions

1. Ignition is on.
2. TFT voltage is more than 4.9 volts for 30 seconds.
3. If vehicle has been exposed to temperatures below -38°F (-38°C).

PCM performs the following if DTC is set

1. Will not light MIL when fault is set.
2. Freezes shift adapts from being updated.
3. Will calculate transaxle temperature based on engine coolant temperature, manifold air temperature and engine run time.
4. DTC P0713 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select "TFT sensor" on scan tool. If scan tool displays transaxle fluid temperature at -40°F (-40°C), go to next step. If scan tool does not display transaxle fluid temperature at -40°F (-40°C), see DIAGNOSTIC AIDS.
3. Turn ignition off. Disconnect transaxle 20-pin connector. Install Jumper Harness (J-39775) to PCM side of transaxle 20-pin connector. Connect fused jumper between transaxle 20-pin connector terminals "L" and "M" (Yellow/Black wire and Black wire). (Scheme 24)Turn ignition switch to ON position. DO NOT start engine.
4. If scan tool does not display transaxle fluid temperature at 304°F (151°C), go to next step. If scan tool displays transaxle fluid temperature at 304°F (151°C), check for open in Yellow/Black wire or Black wire between transaxle 20-pin connector and TFT sensor connector. Repair wire(s) as necessary, then go to step 7). If wire is okay, replace TFP manual valve position switch, then go to step 7).
5. Connect jumper wire between ground and terminal "L" (Yellow/Black wire) at PCM side of transaxle 20-pin connector. If scan tool displays transaxle fluid temperature at 304°F (151°C), go to next step. If scan tool does not display transaxle fluid temperature at 304°F (151°C), check for open in Yellow/Black wire between PCM side of transaxle 20-pin connector and PCM. Repair wire as necessary, then go to step 7). If wire is okay, replace PCM then go to step 7).
6. Check for open in Black wire between PCM side of transaxle 20-pin connector and PCM. Repair wire as necessary, then go to next step.
7. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0713". Turn ignition switch to ON position for more than 3 seconds. TFT signal voltage must be less than 4.9 volts for one minute. If DTC P0713 is not present, repair is complete. If DTC P0713 is still present, repeat test.

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

DTC P0716: INPUT SPEED SENSOR RANGE MALFUNCTION

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS .

Transaxle input speed is signaled to PCM by Input Speed Sensor (ISS). Sensor is a Permanent Magnet (PM) generator. Sensor mounts into transaxle case and maintains slight air gap between sensor and drive sprocket. PM generator produces an AC voltage as drive sprocket rotor teeth pass in front of sensor's magnetic field. AC voltage level increases as speed of turbine shaft increases. PCM converts AC voltage into digital signal. This signal is then used by PCM to determine actual turbine speed. PCM uses input speed to calculate torque converter slip speed and gear ratios. DTC P0716 will set when PCM detects an unrealistic change in input speed.

Conditions For Setting DTC P0716

DTC will set under the following conditions

1. Engine is running.
2. Input speed change is more than 1300 RPM in 0.3 seconds.
3. DTCs P0717 (input speed sensor), P0121, P0122 or P0123 (throttle position), P0502 or P0503 (vehicle speed sensor) P0751, P0753, P0756 or P0758 (1-2 or 2-3 shift solenoid) are not present.
4. Throttle position angle is more than 15 percent.
5. Vehicle speed is more than 5 MPH.

PCM performs the following if DTC is set

1. Will light MIL after 2 consecutive trips with a failure reported.
2. Freezes shift adapts from being updated.
3. Commands maximum line pressure.
4. Inhibits TCC engagement.
5. DTC P0716 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Start engine. Select "Trans ISS" on scan tool. If scan tool displays transaxle input speed less than 500 RPM, go to next step. If scan tool displays transaxle input speed more than 500 RPM, see DIAGNOSTIC AIDS.
3. Turn ignition off. Disconnect transaxle 20-pin connector. Install Jumper Harness (J-39775) to transaxle 20-pin connector. Connect ohmmeter between terminals "S" and "V" of transaxle 20-pin connector. (Scheme 24) If resistance is 615-835 ohms, go to step 6). If resistance is not 615-835 ohms, go to next step.
4. Check for open or short to ground in Red/Black wire between transaxle 20-pin connector and input speed sensor. Repair as necessary, then go to step 8). If wire is okay, go to next step.
5. Check for open or short to ground in Dark Blue/White wire between transaxle 20-pin connector and input speed sensor. Repair as necessary, then go to step 8). If wire is okay, replace input speed sensor, then go to step 8).
6. Turn ignition off. Disconnect Jumper Harness (J-39775) from transaxle side of transaxle 20-pin connector. Reconnect transaxle 20-pin connector. Disconnect both PCM 80-pin connectors. PCM is located under left side of instrument panel, near steering column.
7. On all models, connect voltmeter between input speed sensor terminals at appropriate PCM connector(s) (Dark Blue/White wire and Red/Black wire). Set voltmeter to AC scale. Crank engine. If voltmeter displays more than 0.150 mV (50 Hz), replace PCM, then go to next step. If voltmeter displays less than 0.150 mV (50 Hz), repair open or short to ground in Red/Black wire between transaxle 20-pin connector and PCM. Repair wire as necessary, then go to next step. If wire is okay, repair open or short to ground in Dark Blue/White wire between transaxle 20-pin connector and PCM. If wire is okay, replace PCM, then go to next step.
8. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0716". Shift transaxle to Park and start engine. Transaxle input speed must be more than 50 RPM for 0.8 seconds without a speed change of more than 300 RPM. If DTC P0716 is not present, repair is complete. If DTC P0716 is still present, repeat test.

Diagnostic test checks for input speed sensor circuit problem. If engine is running and vehicle is moving above 7 MPH, input speed must be more than zero. Inspect wiring for poor connections at PCM and at transaxle 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Inspect for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P0717: INPUT SPEED SENSOR CIRCUIT (NO SIGNAL)

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS .

Transaxle input speed is signaled to PCM by Input Speed Sensor (ISS). Sensor is a Permanent Magnet (PM) generator. Sensor mounts into transaxle case and maintains slight air gap between sensor and drive sprocket. PM generator produces an AC voltage as drive sprocket rotor teeth pass in front of sensor's magnetic field. AC voltage level increases as speed of turbine shaft increases. PCM converts AC voltage into digital signal. This signal is then used by PCM to determine actual turbine speed. PCM uses input speed to calculate torque converter slip speed and gear ratios. DTC P0717 will set when PCM detects a low input speed when high vehicle speed exists.

Conditions For Setting DTC P0717

DTC will set under the following conditions

1. DTCs P0502 or P0503 (vehicle speed sensor) and P1810 (pressure switch assembly) are not present.
2. Engine is running.
3. Pressure switch assembly indicates transaxle is not in Park or Neutral.
4. Vehicle speed is more than 5 MPH.
5. Input speed is less than 100 RPM for 5 seconds.

PCM performs the following if DTC is set

1. Will light MIL after 2 consecutive trips with failure reported.
2. Freezes shift adapts from being updated.
3. Commands maximum line pressure.
4. Inhibits TCC engagement.
5. DTC P0717 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Start engine. Select "Trans ISS" on scan tool. If scan tool displays transaxle input speed less than 500 RPM, go to next step. If scan tool displays transaxle input speed more than 500 RPM, see DIAGNOSTIC AIDS.
3. Turn ignition off. Disconnect transaxle 20-pin connector. Install Jumper Harness (J-39775) to transaxle side of transaxle 20-pin connector. Connect ohmmeter to terminals "S" (Red/Black wire) and "V" (Dark Blue/White wire) of transaxle 20-pin connector. If resistance is 615-835 ohms, go to step 8). If resistance is not 615-835 ohms, go to next step.
4. Check for open or short to ground in Red/Black wire between transaxle 20-pin connector and input speed sensor. Repair as necessary, then go to step 8). If wire is okay, go to next step.
5. Check for open or short to ground in Dark Blue/White wire between transaxle 20-pin connector and input speed sensor. Repair as necessary, then go to step 8). If wire is okay, replace input speed sensor, then go to step 8).
6. Turn ignition off. Disconnect Jumper Harness (J-39775) from transaxle side of transaxle 20-pin connector. Reconnect transaxle 20-pin connector. Disconnect both PCM 80-pin connectors. PCM is located under left side of instrument panel, near steering column.
7. On all models, connect voltmeter between input speed sensor terminals at appropriate PCM connector(s) (Dark Blue/White wire and Red/Black wire). (Scheme 25) Set voltmeter to AC scale. Crank engine. If voltmeter displays more than.150 mV (50 Hz), replace PCM, then go to next step. If voltmeter displays less than.150 mV (50 Hz), repair open or short to ground in Red/Black wire between transaxle 20-pin connector and PCM. Repair wire as necessary, then go to next step. If wire is okay, repair open or short to ground in Dark Blue/White wire between transaxle 20-pin connector and PCM. If wire is okay, replace PCM, then go to next step.
8. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0717". Shift transaxle into Park and start engine. Transaxle input speed must be more than 120 RPM for 3 seconds. If DTC P0717 is not present, repair is complete. If DTC P0717 is still present, repeat test.

Diagnostic test checks for input speed sensor circuit problem. If engine is running and vehicle is moving above 7 MPH, input speed must be more than zero. Inspect wiring for poor connections at PCM and at transaxle 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Inspect for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

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

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS .

Torque Converter Clutch (TCC) brake switch is used to indicate brake pedal status to PCM. Normally-closed brake switch supplies battery voltage on circuit No. 420 (Purple wire) to PCM. When brake pedal is applied, brake switch opens, interrupting voltage to PCM. When brake pedal is released, voltage is constant to PCM. When PCM sees zero volts at brake switch input, PCM de-energizes TCC Pulse Width Modulated (PWM) solenoid. DTC P0719 will set when PCM detects an open (stuck on) brake switch during acceleration.

Conditions For Setting DTC P0719

DTC will set under the following conditions

1. PCM detects an open brake switch circuit (zero volts) during acceleration and following conditions occur 6 consecutive times.
2. Vehicle speed is less than 5 MPH, then vehicle speed is between 5-20 MPH for 4 seconds, then vehicle speed is more than 20 MPH for 6 seconds.

PCM performs the following if DTC is set

1. Will not light MIL when fault is set.
2. DTC P0719 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select "Brake Switch" on scan tool. Disconnect brake switch connector. Connect fused jumper between brake switch connector terminals. If brake switch status on scan tool changes from open to closed, go to step 4).
3. If brake switch status on scan tool does not change from open to closed, remove and inspect cruise fuse from instrument panel fuse block. Replace fuse if necessary and check for short to ground in Brown wire between brake switch and fuse block. If wire is okay, go to step 6). If fuse is okay, go to step 5).
4. Check and adjust brake switch as necessary, then go to step 6). If adjustment is okay, replace brake switch, then go to step 6).
5. Check for open in Purple wire between brake switch connector and PCM. Repair wire as necessary, then go to next step. If wire is okay, replace PCM, then go to next step.
6. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0719". Turn ignition switch to ON position. DO NOT apply brake pedal. PCM must receive 12 volts (brake switch closed) on circuit for 3 seconds or more. If DTC P0719 is not present, repair is complete. If DTC P0719 is still present, repeat test.

Ask customer about driving habits and/or unusual traffic conditions such as heavy stop and go driving. Check brake switch for proper adjustment. Inspect wiring for poor connections at PCM and at brake switch connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Inspect for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

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

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS .

Torque Converter Clutch (TCC) brake switch is used to indicate brake pedal status to PCM. Normally-closed brake switch supplies battery voltage on circuit No. 420 (Purple wire) to PCM. When brake pedal is applied, brake switch opens, interrupting voltage to PCM. When brake pedal is released, voltage is constant to PCM. When PCM sees zero volts at brake switch input, PCM de-energizes TCC Pulse Width Modulated (PWM) solenoid. DTC P0724 will set when PCM detects a closed (stuck off) brake switch during deceleration.

Conditions For Setting DTC P0724

DTC will set under the following conditions

1. PCM detects a closed brake switch circuit (12 volts) during deceleration and following conditions occur 6 consecutive times.
2. Vehicle speed is more than 20 MPH for 6 seconds, then vehicle speed is between 5-20 MPH for 4 seconds, then vehicle speed is less than 5 MPH.

PCM performs the following if DTC is set

1. Will not light MIL when fault is set.
2. DTC P0724 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select "Brake Switch" on scan tool. Disconnect brake switch connector. If brake switch status on scan tool changes from closed to open, replace brake switch, then go to next step. If brake switch status on scan tool does not change from closed to open, check for short to voltage in Purple wire between brake switch connector and PCM, then go to next step. If wire is okay, replace PCM, then go to next step.
3. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0724". Turn ignition switch to ON position. Apply brake pedal for 3 seconds or more. If DTC P0724 is not present, repair is complete. If DTC P0724 is still present, repeat test.

Ask customer about driving habits and/or unusual traffic conditions such as heavy stop and go driving. Check brake switch for proper adjustment. Inspect wiring for poor connections at PCM and at brake switch connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Inspect for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P0730: INCORRECT GEAR RATIO

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS .

PCM calculates gear ratio based on transaxle input and output speed sensor readings. PCM compares known transaxle gear ratio to calculated ratio for particular gear range selected. DTC P0730 will set when PCM detects and unknown transaxle gear ratio.

Conditions For Setting DTC P0730

DTC will set under the following conditions

1. DTCs P0121, P0122 and P0123 (throttle position sensor), P0502 and P0503 (vehicle speed sensor), P0716 or P0717 (input speed sensor) and P1810 (pressure switch assembly) are not present.
2. Engine is running.
3. TFP position switch in not in Park or Neutral.
4. Vehicle speed is more than 10 MPH.
5. Engine torque is more than 20 ft. lbs. (25 N.m).
6. Throttle position angle is more than 15 percent.
7. MAP is more than 2.9 psi (20 kPa).
8. Transaxle temperature is more than 14°F (-10°C).
9. 3 seconds has passed since last manual shift change.

All of these conditions exist when any one of the following conditions occur

1. Gear ratio is less than 2.87 or more than 3.13 for 7 seconds.
2. Gear ratio is less than 1.54 or more than 1.71 for 7 seconds.
3. Gear ratio is less than .91 or more than 1.07 for 7 seconds.
4. Gear ratio is less than .61 or more than .72 for 7 seconds.
5. Gear ratio is less than 2.02 or more than 2.23 for 7 seconds.

PCM performs the following if DTC is set

1. Will not light MIL when fault is set.
2. Freezes shift adapts from being updated.
3. Commands maximum line pressure.
4. DTC P0730 will be stored in PCM history.

1. Visually inspect transaxle cooling system for fluid leaks. Repair as necessary, then go to step 5). If no fluid leaks are found, check transaxle fluid level. Fill as necessary. If fluid level is okay, go to next step.
2. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test.
3. Select snapshot mode on scan tool to record transaxle gear ratios. Drive vehicle in 1st, 2nd, 3rd and "D" with throttle position angle more than 15 percent and vehicle speed more than 7 MPH for 5 seconds. Record each gear ratio. Gear ratios should be 2.02-2.23 in Reverse, 2.87-3.13 in 1st gear, 1.54-1.71 in 2nd gear, .91-1.07 in 3rd gear and .61-.72 in "D". If gear ratios are not as specified, go to next step. If gear ratios are as specified, see DIAGNOSTIC AIDS.
4. Perform line pressure test. See HYDRAULIC PRESSURE TEST in AUTO TRANS OVERHAUL - 4T40 article. If line pressure is as specified, check for clutch slippage and repair as necessary, then go to next step. If line pressure is not as specified, repair component(s) as necessary, then go to next step.
5. Because PCM commands maximum line pressure and does not inhibit TCC engagement for DTC P0730, torque converter may need replacement due to possible "ballooning". Check torque converter for "ballooning" and replace as necessary, then go to next step.
6. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0730". Drive vehicle in "D" with throttle position angle more than 15 percent to obtain any one of the following gear ratios for 7 seconds: 2.02-2.23 in Reverse, 2.87-3.13 in 1st gear, 1.54-1.71 in 2nd gear, .91-1.07 in 3rd gear and .61-.72 in "D". If DTC P0730 is not present, repair is complete. If DTC P0730 is still present, repeat test.

Check for intermittent input speed sensor or vehicle speed sensor circuit problems, or for possible incorrect calibration.

DTC P0741: TCC CIRCUIT INOPERATIVE (STUCK OFF)

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS . For fluid circuit ID, see OIL CIRCUIT DIAGRAMS in AUTO TRANS OVERHAUL section.

Torque Converter Clutch (TCC) solenoid is a Pulse Width Modulated (PWM) solenoid. PCM energizes TCC PWM solenoid by grounding circuit No. 418 (Brown wire). When vehicle operating conditions are appropriate to apply TCC, PCM begins TCC PWM duty cycle at about 68 percent. PCM then increases duty cycle up to 93 percent to achieve full TCC apply pressure.

When TCC PWM is de-energized, solenoid blocks filtered 2-3 drive fluid and allows TCC signal fluid to exhaust. When energized, solenoid modulates fluid into TCC signal fluid circuit. When fully energized, modulation stops and solenoid blocks both 2-3 drive fluid and TCC signal fluid from being exhausted. DTC P0741 will set when PCM detects a high TCC slip speed when TCC is commanded on.

Conditions For Setting DTC P0741

DTC will set under the following conditions

1. DTCs P0121, P0122 or P0123 (throttle position sensor), P0502 or P503 (vehicle speed sensor), P0742 (TCC stuck on), P1810 (pressure switch assembly) or P1887 (TCC release switch) are not present.
2. Throttle position angle is 10-75 percent.
3. 3 seconds has passed since last manual shift change.
4. TFP position switch indicates "2", "3" or "D" position.
5. Transaxle fluid temperature is 86-212°F (30-110°C).
6. PCM commands TCC on for more than 3 seconds.
7. Commanded gear is 2nd, 3rd or "D".
8. TCC slip speed is 300 RPM or more for 5 seconds 2 consecutive times.

PCM performs the following if DTC is set

1. Will light MIL after 2 consecutive trips with first failure reported.
2. Inhibits TCC engagement.
3. Freezes shift adapts from being updated.
4. DTC P0741 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. If DTCs P0753 and P0758 are present, go to next step. If DTCs P0753 and P0758 are not present, go to step 3).
2. Turn ignition off. Remove and inspect AUTO TRANS fuse from instrument panel fuse block. Replace fuse if necessary and check for short to ground in Pink wire between transaxle 20-pin connector and fuse block. If fuse is okay, check for open in Pink wire. Repair wire as necessary. If wire is okay, go to step 6).
3. Turn ignition off. Disconnect transaxle 20-pin connector. Install Jumper Harness (J-39775) to PCM side of transaxle 20-pin connector. Connect test light between ground and terminal "E" (Pink wire) of transaxle 20-pin connector. Turn ignition switch to ON position. DO NOT start engine. If test light is on, go to next step. If test light is off, check for open in Pink wire between terminal "E" and splice in wiring harness to PCM, then go to step 9).
4. Connect test light between transaxle 20-pin connector terminals "E" and "T" (Pink wire and Brown wire). Select "TCC Duty Cycle" on scan tool. Command TCC duty cycle to 100 percent, then to zero. If test light is on when TCC duty cycle is commanded to 100 percent and is off at zero, go to step 6).
5. If test light is not on when TCC duty cycle is commanded to 100 percent and is not off at zero, check for open in Brown wire between transaxle 20-pin connector and PCM. Repair wire as necessary, then go to step 9). If wire is okay, replace PCM, then go to step 9).
6. Disconnect Jumper Harness (J-39775) from PCM side of transaxle 20-pin connector and install harness on transaxle side of 20-pin connector. Connect ohmmeter between terminals "E" and "T" (Red wire and Tan wire) of transaxle 20-pin connector.
7. If resistance is 10-15 ohms, go to next step. If resistance is not 10-15 ohms, check for open in Red wire or Tan wire between transaxle 20-pin connector and TCC PWM solenoid. Repair wires as necessary, then go to step 9). If wires are okay, replace TCC PWM solenoid, then go to step 9).
8. Repair TCC PWM shift valve circuit. Inspect for the following: Leak at TCC PWM solenoid, TCC regulator apply valve or control valve stuck in release position, or plugged TCC PWM solenoid filter. Repair components as necessary, then go to next step.
9. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0741". Drive vehicle in "D" with throttle position more than 10 percent to obtain 45 MPH. With TCC commanded on and engaged, slip speed must be less than 300 RPM for 3 seconds. If DTC P0741 is not present, repair is complete. If DTC P0741 is still present, repeat test.

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

DTC P0742: TCC CIRCUIT INOPERATIVE (STUCK ON)

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS . For fluid circuit ID, see OIL CIRCUIT DIAGRAMS in AUTO TRANS OVERHAUL section.

Torque Converter Clutch (TCC) release switch is part of Pressure Switch Assembly (PSA) (also referred to as Transaxle Fluid Pressure (TFP) manual valve position switch), which is mounted to transaxle valve body. Switch is normally-closed. Switch provides signal to PCM when TCC is released. This is accomplished by TCC release fluid pressure acting on switch contact and opening circuit. When voltage is high on circuit No. 657/1804 (Yellow wire and White wire), PCM recognizes TCC is no longer engaged. DTC P0742 will set when PCM detects TCC release switch is closed when TCC is commanded off.

Conditions For Setting DTC P0742

DTC will set under the following conditions

1. DTCs P0121, P0122 or P0123 (throttle position sensor) are not present.
2. DTC P1887 (TCC release) is not present.
3. Engine is running.
4. Throttle position angle is more than 20 percent.
5. 3 seconds has passed since last manual shift change.
6. TCC is commanded off.
7. All conditions are met for 8 seconds.

PCM performs the following if DTC is set

1. Will light MIL at first failure signal.
2. Freezes shift adapts from being updated.
3. TCC will be commanded on.
4. DTC P0742 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select "TCC Release Switch" on scan tool. If TCC release switch status on scan tool is not closed, see DIAGNOSTIC AIDS. If TCC release switch status on scan tool is closed, start engine. If TCC release switch status on scan tool is open, go to step 6). If TCC release switch status on scan tool is closed, go to next step.
3. Turn ignition off. Disconnect transaxle 20-pin connector. Turn ignition switch to ON position. DO NOT start engine. If TCC release switch status on scan tool is open, go to next step. If TCC release switch status on scan tool is closed, go to step 5).
4. Check for short to ground in White wire between transaxle 20-pin connector and PSA. Repair wire as necessary. If wire is okay, go to step 9).
5. Check for short to ground in Yellow wire between transaxle 20-pin connector and PCM. Repair wire as necessary. If wire is okay, replace TCC PWM solenoid, then go to step 11).
6. Install Jumper Harness (J-39775) to PCM side of transaxle 20-pin connector. Connect test light between battery voltage and terminal "T" (Brown wire) of transaxle 20-pin connector. If test light is off, go to next step. If test light is on, check for short to ground in Brown wire between transaxle 20-pin connector and PCM. Repair as necessary, then go to step 11). If wire is okay, replace PCM, then go to step 11).
7. Turn ignition off. Disconnect Jumper Harness (J-39775) from PCM side of transaxle 20-pin connector and connect harness to transaxle side of 20-pin connector. Connect test light between battery voltage and terminal "T" (Tan wire) of transaxle 20-pin connector. If test light is off, go to step 10).
8. If test light is on, check for short to ground in Tan wire between transaxle 20-pin connector and TCC PWM solenoid. Repair wire as necessary, then go to step 11). If wire is okay, check TCC PWM solenoid for internal short. Replace solenoid as necessary, then go to step 11).
9. Remove PSA and inspect TCC release switch for cut, damaged or leaking seal, sediment or debris in switch or damaged or stuck switch contacts. Repair or replace TCC release switch as necessary. If switch is okay, replace PSA, then go to step 11).
10. Inspect TCC PWM hydraulic circuit. Check for plugged TCC PWM solenoid exhaust, TCC regulator apply valve or control valve stuck in apply position, TCC feed limit valve stuck, causing no or low TCC feed limit pressure and release pressure or stuck pressure regulator valve. Repair or replace component as necessary, then go to next step.
11. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0742". Drive vehicle in "D" with throttle position angle more than 20 percent. TCC release oil must be present at TCC release switch (switch open) for 3 seconds. If DTC P0742 is not present, repair is complete. If DTC P0742 is still present, repeat test.

Rapid fluctuation in line pressure could set DTC P0742. Check for pressure regulator malfunction and low or high line pressure. Inspect wiring for poor connections at PCM and at transaxle 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Inspect for broken wire inside insulation. Customer may notice an engine stalling condition. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P0748: PRESSURE CONTROL SOLENOID ELECTRICAL MALFUNCTION

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS .

Pressure Control Solenoid (PCS) is used to regulate transaxle line pressure. PCS consists of an electrical connector, coil, armature, regulating spring and a poppet valve. PCS is attached to upper control valve body. PCM compares TP voltage, fluid temperature, gear status and other inputs to determine line pressure appropriate for given load. PCM will regulate pressure by applying varying amperage to PCS. Applied amperage can vary from .1-1.0 amps. PCM then monitors amperage at return line. DTC P0748 will set when PCM detects a continuous open or short to ground in PCS circuit to PCS solenoid.

Conditions For Setting DTC P0748

DTC will set under the following conditions

1. System voltage is 10-16 volts.
2. Actual return amperage is .16 amp higher or lower than desired amperage.
3. Extended engine cranking with weak battery.

PCM performs the following if DTC is set

1. Will not light MIL when fault is set.
2. Freezes shift adapts from being updated.
3. Commands maximum line pressure (zero amps).
4. DTC P0748 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Start engine. Using scan tool, apply.1-1.0 amp and observe scan tool display. If PCS actual amperage reading is not within 0.16 amp of desired reference amperage reading, go to next step. If PCS actual amperage reading is within.16 amp of desired reference amperage reading, see DIAGNOSTIC AIDS.
3. Turn ignition off. Disconnect transaxle 20-pin connector. Install Jumper Harness (J-39775) to transaxle side of 20-pin connector. Connect ohmmeter between terminals "C" and "D" (Red/Black wire and Light Blue/White wire) of transaxle 20-pin connector. If resistance is 3-7 ohms, go to step 6).
4. If resistance is not 3-7 ohms, but resistance is more than 7 ohms, check for open in Red/Black wire and Light Blue/White wire between transaxle 20-pin connector and PCS. Repair wires as necessary, then go to step 12). If wires are okay, replace pressure control solenoid, then go to step 12).
5. If resistance is less than 3 ohms, ensure Red/Black wire and Light Blue/White wire are not shorted together. Repair wires as necessary, then go to step 12). If wires are okay, replace pressure control solenoid, then go to step 12).
6. Connect ohmmeter between ground and terminal "D" (Light Blue/White wire) of transaxle 20-pin connector. If resistance is more than 1000 ohms, go to next step. If resistance is less than 1000 ohms, check for short to ground in Red/Black wire and Light Blue/White wire between transaxle 20-pin connector and pressure control solenoid. Repair wires as necessary, then go to step 12). If wires are okay, replace pressure control solenoid, then go to step 12).
7. Disconnect jumper harness from transaxle 20-pin connector and install harness on PCM side of transaxle 20-pin connector. Disconnect PCM 80-pin connector C2 (Clear). (Scheme 25) PCM on is located below left side of instrument panel, near steering column.
8. Connect ohmmeter between ground and terminal "D" (Light Blue/White wire) of transaxle 20-pin connector. If resistance is more than 10 ohms, go to next step. If resistance is less than 10 ohms, check for short to ground in Light Blue/White wire between transaxle 20-pin connector and PCM. Repair wire as necessary, then go to step 12).
9. Connect ohmmeter between terminal "D" of transaxle 20-pin connector and terminal No. 9 (Light Blue/White wire) of PCM 80-pin connector C2. (Scheme 25) If resistance is less than 10 ohms, go to next step. If resistance is more than 10 ohms, check for open in Light Blue/White wire. Repair wire as necessary, then go to step 12).
10. Connect ohmmeter between ground and terminal "C" (Red/Black wire) of transaxle 20-pin connector. If resistance is more than 10 ohms, go to next step. If resistance is less than 10 ohms, check for short to ground in Red/Black wire. Repair wire as necessary, then go to step 12).
11. Connect ohmmeter between terminal "C" of transaxle 20-pin connector and terminal No. 6 (Red/Black wire) of PCM 80-pin connector C2. (Scheme 25) If resistance is less than 10 ohms, replace PCM, then go to next step. If resistance is more than 10 ohms, check for open in Red/Black wire. Repair wire as necessary, then go to next step.
12. Because PCM commands maximum line pressure and does not inhibit TCC engagement for DTC P0748, torque converter may need replacement due to possible "ballooning". Check torque converter for "ballooning" and replace as necessary, then go to next step.
13. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0748". Turn ignition switch to ON position. PCS actual return amperage must be.16 amp of commanded amperage. If DTC P0748 is not present, repair is complete. If DTC P0748 is still present, repeat test.

Inspect wiring for poor connections at PCM and at transaxle 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Inspect for broken wire inside insulation. Extended engine cranking with a weak battery could set DTC P0748. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

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

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS .

The 1-2 shift solenoid (solenoid "A") is a normally-open exhaust valve that is used in conjunction with 2-3 shift solenoid (solenoid "B"), to allow 4 different shifting combinations. Solenoid is attached to control valve body. DTC will set when shift solenoid or shift valve is stuck on or off. DTC P0751 will set when PCM detects that commanded gear does not match actual gear ratio for that particular gear. See COMMANDED & ACTUAL GEAR RATIO REFERENCE TABLE .

Conditions For Setting DTC P0751

DTC will set under the following conditions

1. DTCs P0121, P0122 and P0123 (throttle position sensor), P0502 and P0503 (vehicle speed sensor), P0716 or P0717 (input speed sensor), P0753 and P0758 (shift solenoid) and P1810 (pressure switch assembly) are not present.
2. Engine is running.
3. Transaxle position switch is not in Park, Reverse or Neutral.
4. Vehicle speed is more than 5 MPH.
5. Throttle position angle is more than 8 percent.
6. Engine torque is 20 ft. lbs. (25 N.m).
7. MAP is more than 2.9 psi (20 kPa).
8. Transaxle temperature is more than 14°F (-10°C).

All conditions exist when any one of the following conditions occur

1. PCM commands 1st gear and gear ratio is between 1.54-1.71 (2nd gear) for 2 seconds. This must occur 2 consecutive times.
2. PCM commands 2nd gear and gear ratio is between 2.87-3.13 (1st gear) for 4 seconds. This must occur 2 consecutive times.
3. PCM commands 3rd gear and gear ratio is between .67-.72 (4th gear) for 5 seconds. This must occur 2 consecutive times.
4. PCM commands 4th gear and gear ratio is between .93-1.05 (3rd gear) for 3 seconds. This must occur 2 consecutive times.

PCM performs the following if DTC is set

1. Will light MIL at first failure signal.
2. Freezes shift adapts from being updated.
3. Commands maximum line pressure.
4. Commands soft shift to 2nd gear.
5. Inhibits TCC engagement.
6. DTC P0751 will be stored in PCM history.

COMMANDED & ACTUAL GEAR RATIO REFERENCE

1. Check transaxle fluid level. Fill as needed. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select snapshot mode on scan tool. Record current gear and gear ratio. Drive vehicle in "D" to obtain 1-2 shift with throttle position angle more than 10 percent and vehicle speed more than 5 MPH for 5 seconds. If current gear is 2nd and gear ratio is within 2.87-3.13, and commanded gear is 3rd and gear ratio is .67-.72, go to next step. If current gear is 1st and gear ratio is 1.54-1.71, and commanded gear is 4th and gear ratio is within .91-1.07, go to step 4).
3. Repair 1-2 shift circuit. Check 1-2 shift circuit for 1-2 shift solenoid mechanically stuck on, or 1-2 shift valve stuck in applied (upshift) position. Repair as necessary, then go to step 5).
4. Repair 1-2 shift circuit. Check 1-2 shift circuit for 1-2 shift solenoid mechanically stuck off, 1-2 shift solenoid "O" ring damage or 1-2 shift valve stuck in released (downshift) position. Repair as necessary, then go to next step.
5. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0751". Drive vehicle in "D" position. Allow transaxle to shift through all gears. Actual gear ratios must match commanded gears for 3 seconds for all gears. See «COMMANDED & ACTUAL GEAR RATIO REFERENCE TABLE»(/chevrolet/malibu/v-1996-2000/remont/automatic-trans/#automatic-transaxle-diagnosis-4t40-e-24l) . If DTC P0751 is not present, repair is complete. If DTC P0751 is still present, repeat test.

Check for stuck throttle position sensor. If DTC P0751 cannot be reset after clearing code, check for possible fluid contamination or plugged or restricted oil circuits.

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

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS .

The 1-2 shift solenoid (solenoid "A") is used to control fluid flow acting on 1-2 shift valve. Solenoid is a normally-open valve that is used in conjunction with 2-3 shift solenoid (solenoid "B"), to allow 4 different shifting combinations. See SHIFT SOLENOID COMBINATIONS table. Solenoid is attached to control valve body. Ignition voltage is supplied directly to solenoid through fused circuit. PCM commands solenoid on or off by providing a ground path through circuit No. 1222 (Light Green Wire). DTC P0753 will set when PCM detects a continuous open, short to ground or short to voltage in 1-2 shift solenoid circuit.

Conditions For Setting DTC P0753

DTC will set under the following conditions

1. Ignition is on.
2. PCM commands solenoid on and voltage remains high for 4.3 seconds.

PCM performs the following if DTC is set

1. Will light MIL at first failure signal.
2. Freezes shift adapts from being updated.
3. Commands maximum line pressure.
4. Commands soft shift to 2nd gear.
5. Inhibits TCC engagement.
6. DTC P0753 will be stored in PCM history.

SHIFT SOLENOID COMBINATIONS

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. If DTCs P0719, P0724 or P0758 are not present, go to next step. If DTCs P0719, P0724 or P0758 are present, remove AUTO TRANS fuse from instrument panel fuse block and inspect fuse. Replace fuse if necessary, and check for short to ground in Pink wire between transaxle 20-pin connector and fuse block. Repair wire as necessary, then go to step 12). If fuse is okay, check for open in Pink wire between transaxle 20-pin connector and fuse block. Repair wire as necessary, then go to step 12).
3. Using scan tool, command 1-2 shift solenoid on and off 3 times. Listen at transaxle side cover. If solenoid does not click when commanded on and off, go to next step. If solenoid clicks when commanded on and off, see DIAGNOSTIC AIDS.
4. Turn ignition off. Disconnect transaxle 20-pin connector. Install Jumper Harness (J-39775) to PCM side of transaxle 20-pin connector. Connect test light between terminals "A" and "E" (Light Green wire and Pink wire) of transaxle 20-pin connector. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, command 1-2 shift solenoid on and off 3 times.
5. If test light cycles on and off 3 times, go to step 8). If test light does not cycle on and off 3 times, and test light is always on, go to next step. If test light is always off, go to step 7).
6. Turn ignition off. Disconnect PCM 80-pin connector C2. (Scheme 25) PCM is located below left side of instrument panel, near steering column. On all models, turn ignition switch to ON position. Ensure test light is still connected between terminals "A" and "E" (Light Green wire and Pink wire) of transaxle 20-pin connector. If test light is off, go to next step. If test light is on, check for short to ground in Light Green wire between transaxle 20-pin connector and PCM. Repair wire as necessary, then go to step 12).
7. Check for open in Light Green wire between transaxle 20-pin connector and PCM. Repair wire as necessary, then go to step 12). If wire is okay, go to step 11).
8. Turn ignition off. Disconnect jumper harness from PCM side of transaxle 20-pin connector and install harness to transaxle side of 20-pin connector. Connect ohmmeter between terminals "A" and "E" (Light Green wire and Pink wire) of transaxle 20-pin connector.
9. If resistance is 19-31 ohms, go to next step. If resistance is not 19-31 ohms but is more than 250 ohms, check for open or poor connection in Light Green wire and Pink wire at connector. Repair wire or connector as necessary, then go to step 12). If resistance is not 19-31 ohms but is less than 250 ohms, go to next step.
10. Connect ohmmeter between ground and terminal "A" (Light Green wire) of transaxle 20-pin connector. If resistance is more than 1000 ohms, replace 1-2 shift solenoid, then go to step 12). If resistance is less than 1000 ohms, check for short to ground in Light Green wire between transaxle 20-pin connector and 1-2 shift solenoid. Repair wire as necessary, then go to step 12).
11. Connect test light between ground and terminal "A" (Light Green wire) of transaxle 20-pin connector. If test light is off, replace PCM, then go to next step. If test light is on, check for short to battery voltage in Light Green wire between transaxle 20-pin connector and 1-2 shift solenoid. Repair wire as necessary, then go to next step.
12. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0753". Place transaxle in Park and start engine. Allow engine to idle for 5 seconds. If DTC P0753 is not present, repair is complete. If DTC P0753 is still present, repeat test.

An open in Pink wire between transaxle 20-pin connector and fuse can cause multiple DTCs to set. Inspect wiring for poor connections at PCM and at transaxle 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Inspect for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

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

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS .

The 2-3 shift solenoid (solenoid "B") is a normally-open exhaust valve that is used in conjunction with 1-2 shift solenoid (solenoid "A"), to allow 4 different shifting combinations. Solenoid is attached to control valve body. DTC will set when shift solenoid or shift valve is stuck on or off.

DTC P0756 will set when PCM detects a 1st gear ratio when commanded gear is 2nd, a 4th gear ratio when commanded gear is 3rd, a 2nd gear ratio when commanded gear is 1st, or a 3rd gear ratio when commanded gear is 4th. See COMMANDED & ACTUAL GEAR RATIO REFERENCE TABLE .

Conditions For Setting DTC P0756

DTC will set under the following conditions

1. DTCs P0121, P0122 and P0123 (throttle position sensor), P0502 or P0503 (vehicle speed sensor), P0712 and P0713 (transaxle fluid temperature), P0716 or P0717 (input speed sensor), DTC P0753 or P0758 (shift solenoid performance), DTC P1644 (engine torque) and P1810 (pressure switch assembly) are not present.
2. Engine is running.
3. Transaxle position switch indicates D4, D3, D2 or D1.
4. Vehicle speed is more than 5 MPH.
5. Throttle position angle is more than 8 percent.
6. MAP is more than 2.9 psi (20 kPa), transaxle temperature is more than 14°F ('10°C).

All conditions exist when any one of the following conditions occur

1. PCM commands 1st gear and gear ratio is between .67-.72 (4th gear) for 2 seconds. This must occur 2 consecutive times.
2. PCM commands 2nd gear and gear ratio is between .93-1.05 (3rd gear) for 5 seconds. This must occur 2 consecutive times.
3. PCM commands 3rd gear and gear ratio is between 1.54-1.71 (2nd gear) for 5 seconds. This must occur 2 consecutive times.
4. PCM commands 4th gear and gear ratio is between 2.87-3.13 (1st gear) for 5 seconds. This must occur 2 consecutive times.

PCM performs the following if DTC is set

1. Will light MIL at first failure signal.
2. Freezes shift adapts from being updated.
3. Commands maximum line pressure.
4. Commands immediate shift to 2nd gear.
5. Inhibits TCC engagement.
6. DTC P0756 will be stored in PCM history.

1. Check transaxle fluid level. Fill as needed. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select snapshot mode on scan tool. Record current gear and gear ratio. Drive vehicle in "D" to obtain 2-3 shift with throttle position angle more than 15 percent and vehicle speed more than 7 MPH for 6 seconds. If 1st gear ratio is 2.87-3.13, and 4th gear ratio is .61-.72, see DIAGNOSTIC AIDS.
3. If 1st gear ratio is not 2.87-3.13, and 4th gear ratio is not .61-.72, determine if engine labors during start off and 3rd gear is indicated when 1st gear is commanded. If engine does not labor during start off and 3rd is not indicated when 1st gear is commanded, go to next step. If engine labors during start off and 3rd gear is indicated when 1st gear is commanded, go to step 5).
4. Repair 2-3 shift circuit. Check 2-3 shift circuit for 2-3 shift solenoid mechanically stuck off, 2-3 shift solenoid "O" ring damage or 2-3 shift valve stuck in released (downshift) position. Repair as necessary, then go to step 6).
5. Repair 2-3 shift circuit. Check 2-3 shift circuit for 2-3 shift solenoid mechanically stuck on, or 2-3 shift valve stuck in applied (upshift) position. Repair as necessary, then go to next step.
6. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0756". Drive vehicle in "D" position. Allow transaxle to shift through all gears. Actual gear ratios must match commanded gears for 3 seconds for all gears. See «COMMANDED & ACTUAL GEAR RATIO REFERENCE TABLE»(/chevrolet/malibu/v-1996-2000/remont/automatic-trans/#automatic-transaxle-diagnosis-4t40-e-24l) . If DTC P0756 is not present, repair is complete. If DTC P0756 is still present, repeat test.

If DTC P0756 cannot be reset after clearing code, check for possible fluid contamination or plugged or restricted oil circuit.

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

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS .

The 2-3 shift solenoid (solenoid "B") is used to control fluid flow acting on 2-3 shift valve. Solenoid is a normally-open valve that is used in conjunction with 1-2 shift solenoid (solenoid "A"), to allow 4 different shifting combinations. See SHIFT SOLENOID COMBINATIONS table. Solenoid is attached to control valve body. Ignition voltage is supplied directly to solenoid through fused circuit. PCM commands solenoid on or off by providing a ground path through circuit No. 1223 (Yellow/Black Wire). DTC P0758 will set when PCM detects a continuous open, short to ground or short to voltage in 2-3 shift solenoid circuit.

Conditions For Setting DTC P0758

DTC will set under the following conditions

1. Ignition is on.
2. PCM commands solenoid on and voltage remains high for 4.3 seconds.

PCM performs the following if DTC is set

1. Will light MIL at first failure signal.
2. Freezes shift adapts from being updated.
3. Commands maximum line pressure.
4. Commands immediate shift to 2nd gear.
5. Inhibits TCC engagement.
6. DTC P0758 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. If DTCs P0719 or P0753 are not present, go to next step. If DTCs P0719 or P0753 are present, remove AUTO TRANS fuse from instrument panel fuse block and inspect fuse. Replace fuse if necessary, and check for short to ground in Pink wire between transaxle 20-pin connector and fuse block. Repair wire as necessary, then go to step 12). If fuse is okay, check for open in Pink wire between transaxle 20-pin connector and fuse block. Repair wire as necessary, then go to step 12).
3. Using scan tool, command 2-3 shift solenoid on and off 3 times. Listen at transaxle side cover. If solenoid does not click when commanded on and off, go to next step. If solenoid clicks when commanded on and off, see DIAGNOSTIC AIDS.
4. Turn ignition off. Disconnect transaxle 20-pin connector. Install Jumper Harness (J-39775) to PCM side of transaxle 20-pin connector. Connect test light between terminals "B" and "E" (Yellow/Black wire and Pink wire) of transaxle 20-pin connector. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, command 2-3 shift solenoid on and off 3 times.
5. If test light cycles on and off 3 times, go to step 8). If test light does not cycle on and off 3 times, and test light is always on, go to next step. If test light is always off, go to step 7).
6. Turn ignition off. Disconnect PCM 80-pin connector C2. (Scheme 25) PCM is located below left side of instrument panel, near steering column. On all models, turn ignition switch to ON position. Ensure test light is still connected between terminals "B" and "E" (Yellow/Black wire and Pink wire) of transaxle 20-pin connector. If test light is off, go to next step. If test light is on, check for short to ground in Yellow/Black wire between transaxle 20-pin connector and PCM. Repair wire as necessary, then go to step 12).
7. Check for open in Yellow/Black wire between transaxle 20-pin connector and PCM. Repair wire as necessary, then go to step 12). If wire is okay, go to step 11).
8. Turn ignition off. Disconnect jumper harness from PCM side of transaxle 20-pin connector and install harness to transaxle side of 20-pin connector. Connect ohmmeter between terminals "B" and "E" (Yellow/Black wire and Pink wire) of transaxle 20-pin connector.
9. If resistance is 19-31 ohms, go to next step. If resistance is not 19-31 ohms but is more than 250 ohms, check for open or poor connection in Yellow/Black wire and Pink wire at connector. Repair wire or connector as necessary, then go to step 12). If resistance is not 19-31 ohms but is less than 250 ohms, go to next step.
10. Connect ohmmeter between ground and terminal "B" (Yellow/Black wire) of transaxle 20-pin connector. If resistance is more than 1000 ohms, replace 2-3 shift solenoid, then go to step 12). If resistance is less than 1000 ohms, check for short to ground in Yellow/Black wire between transaxle 20-pin connector and 2-3 shift solenoid. Repair wire as necessary, then go to step 12).
11. Connect test light between ground and terminal "B" (Yellow/Black wire) of transaxle 20-pin connector. If test light is off, replace PCM, then go to next step. If test light is on, check for short to battery voltage in Yellow/Black wire between transaxle 20-pin connector and 2-3 shift solenoid. Repair wire as necessary, then go to next step.
12. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P0758". Drive vehicle in "D". Allow transaxle to perform 2-3 upshift. If DTC P0758 is not present, repair is complete. If DTC P0758 is still present, repeat test.

An open in Pink wire between shift solenoid and fuse can cause multiple DTCs to set. Check for stuck throttle position sensor. Inspect wiring for poor connections at PCM and at transaxle 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Inspect for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P1810: PRESSURE SWITCH ASSEMBLY (PSA) MALFUNCTION

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS . Pressure switch assembly is also referred to as Transaxle Fluid Pressure (TFP) manual valve position switch.

Transaxle Pressure Switch Assembly (PSA) consists of 6 pressure switches. One switch is normally-closed and is used to detect TCC release fluid pressure. Other switches are normally-open and are used for determining gear range selection. PSA also contains Transaxle Fluid Temperature (TFT) sensor. These components are combined into one unit and mounted on control valve body.

PCM provides battery voltage on each range signal. By grounding one or more switches with fluid pressure from manual shift valve, PCM detects selected gear range. When transaxle electrical connector is disconnected and ignition is on, ground potential for 3 range signals from PCM will be removed, and an illegal gear will be indicated. See PSA LOGIC TABLE . DTC P1810 will set when PCM detects an invalid gear status, a drive range after start-up or an incorrect gear ratio.

PSA LOGIC

Conditions For Setting DTC P1810

DTC will set when any one of the following 3 conditions occur

1. Engine is running.
2. Gear range is illegal for 5 seconds.

Condition No. 1 & Condition No. 2

1. Engine speed is in transition from zero to more than 500 RPM.
2. D2, D4 or Reverse gear is indicated after start-up for 2 seconds.
3. DTCs P0502 or P0503 (vehicle speed sensor) are not present.
4. Vehicle speed is less than 2 MPH.
5. System voltage is 10-16 volts.

Condition No. 3

1. Engine is running.
2. DTCs P0121, P0122 or P0123 (throttle position), P0716 or P0717 (input speed sensor) or P0502 and P0503 (vehicle speed sensor) are not present.
3. DTCs P0751, P0753, P0756 or P0758 (1-2 and 2-3 shift solenoid) are not present.
4. Engine torque is more than 10 ft. lbs ( 14 N.m).
5. MAP is 1.5-15 psi (10-105 kPa).
6. Throttle position angle is equal to or more than 10 percent.
7. Vehicle speed is 5 MPH or more.

One of the following 3 conditions must also occur

1. PSA indicates Park/Neutral when gear ratio is less than .72 (4th gear) for 5 seconds
2. PSA indicates Reverse when gear ratio is more than 2.23 or less than 2.02 for 5 seconds
3. PSA indicates gear position other than Park or Neutral when gear ratio indicates Reverse for 5 seconds.

PCM performs the following if DTC is set

1. Will light MIL after 2 consecutive trips with a failure signal.
2. Freezes shift adapts from being updated.
3. Increases line pressure.
4. Assumes "D" shift pattern.
5. Inhibits TCC engagement.
6. DTC P1810 will be stored in PCM history.

1. Check transaxle fluid. Fill as needed. Ensure transaxle shift linkage is adjusted correctly. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Apply parking brake. Start engine and apply brake. Shift transaxle into each gear selector lever position while monitoring scan tool Transaxle Range (TR) switch display. See «PSA LOGIC TABLE»(/chevrolet/malibu/v-1996-2000/remont/automatic-trans/#automatic-transaxle-diagnosis-4t40-e-24l) . If each selected lever position does not match scan tool display, go to next step. If each selected lever position matches scan tool display, see DIAGNOSTIC AIDS.
3. Turn ignition off. Disconnect transaxle 20-pin connector. Turn ignition switch to ON position. DO NOT start engine. If scan tool TR switch does not display "A" Off, "B" Off and "C" Off, go to next step. If scan tool TR switch displays "A" Off, "B" Off and "C" Off, go to step 5).
4. If scan tool TR switch displays "A" On, check for short to ground in Pink wire between transaxle 20-pin connector and PSA. If scan tool TR switch displays "B" On, check for short to ground in Dark Blue wire between transaxle 20-pin connector and PSA. If scan tool TR switch displays "C" On, check for short to ground in Red wire between transaxle 20-pin connector and PCM. Repair wire(s) as necessary, then go to step 11). If wires are okay, replace PCM, then go to step 11). NOTE: When performing steps 5), 6) and 7), if 2 or more signal ranges display ON, those circuits are shorted together.
5. Install Jumper Harness (J-39775) to PCM side of transaxle 20-pin connector. Connect fused jumper between ground and terminal "N" (Pink wire) of transaxle 20-pin connector. If scan tool TR switch displays signal "A" On, go to next step. If scan tool TR switch does not display signal "A" On, check for open in Pink wire between transaxle 20-pin connector and PCM. Repair wire as necessary, then go to step 11). If wire is okay, replace PCM, then go to step 11).
6. Connect fused jumper between ground and terminal "R" (Dark Blue wire) of transaxle 20-pin connector. If scan tool TR switch displays signal "B" On, go to next step. If scan tool TR switch does not display signal "B" On, check for open in Dark Blue wire between transaxle 20-pin connector and PCM. Repair wire as necessary, then go to step 11). If wire is okay, replace PCM, then go to step 11).
7. Connect fused jumper between ground and terminal "P" (Red wire) of transaxle 20-pin connector. If scan tool TR switch displays signal "C" On, go to next step. If scan tool TR switch does not display signal "C" On, check for open in Red wire between transaxle 20-pin connector and PCM. Repair wire as necessary, then go to step 11). If wire is okay, replace PCM then go to step 11).
8. Turn ignition off. Disconnect jumper harness from PCM side of transaxle 20-pin connector and install harness on transaxle side of 20-pin connector. Connect ohmmeter between ground and terminal "N" (Pink wire) of transaxle 20-pin connector. If resistance is more than 1000 ohms, go to next step. If resistance is less than 1000 ohms, check for open or short to ground in Pink wire between transaxle 20-pin connector and PSA. Repair wire as necessary, then go to step 11). If wire is okay, replace PSA, then go to step 11).
9. Connect ohmmeter between ground and terminal "R" (Dark Blue wire) of transaxle 20-pin connector. If resistance is more than 1000 ohms, go to next step. If resistance is less than 1000 ohms, check for open or short to ground in Dark Blue wire between transaxle 20-pin connector and PSA. Repair wire as necessary, then go to step 11). If wire is okay, replace PSA, then go to step 11).
10. Connect ohmmeter between ground and terminal "P" (Red wire) of transaxle 20-pin connector. If resistance is more than 1000 ohms, replace PSA, then go to next step. If resistance is less than 1000 ohms, check for open or short to ground in Red wire between transaxle 20-pin connector and PSA. Repair wire as necessary, then go to next step. If wire is okay, replace PSA, then go to next step.
11. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P1810". Drive vehicle in "D" with throttle position angle more than 10 percent. Allow transaxle to shift through all gears. If DTC P1810 is not present, repair is complete. If DTC P1810 is still present, repeat test.

A pressure regulator malfunction could set DTC P1810. Inspect wiring for poor connections at PCM and at transaxle 20-pin connector. Check for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Check for chafed wire that could short to bare metal or other wiring. Inspect for broken wire inside insulation. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P1811: MAXIMUM ADAPT & LONG SHIFTS

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

Transaxle line pressure is modified by PCM through Pressure Control Solenoid (PCS) to control gear shift execution time and shift consistency. PCM monitors various inputs and modifies shift execution and timing by applying a calculated duty cycle to PCS. PCM alters shifting based on driving habits, transaxle load and internal transaxle condition. DTC P1811 will set when PCM detects long shifts that cannot be shortened by shift adapts during same ignition cycle.

Conditions For Setting DTC P1811

DTC will set under the following condition

1. When shift time is more than one second at maximum adapt for a total 4 times per ignition cycle.

PCM performs the following if DTC is set

1. Will not light MIL when fault is set.
2. Freezes shift adapts from being updated.
3. Commands maximum line pressure.
4. DTC P1811 will be stored in PCM history.

1. Check transaxle fluid. Fill as needed. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select snapshot on scan tool to record shift times. Drive vehicle in D4 to obtain 1-2, 2-3 and 3-4 upshifts. If all shifts exceeded one second, perform line pressure test. See HYDRAULIC PRESSURE TEST in AUTO TRANS OVERHAUL - 4T40 article. If line pressure is not within specification, go to next step. If line pressure is within specification, see DIAGNOSTIC AIDS. If all shifts did not exceed one second, go to step 4).
3. Inspect transaxle for low fluid level, external leaks, fluid filter clogged or out of position, internal fluid passage leaks, casting porosity or damage, damaged or out of position gaskets or spacer plate. Check for contaminated, stuck or damaged PCS or pressure regulator valve stuck or leaking. Check for torque signal valve stuck or leaking, leaking or damaged oil pump, or inadequate suction or pump cavitation. Repair component(s) as necessary, then go to step 9).
4. If 1-2 shift exceeded one second, go to next step. If 2-3 shift exceeded one second, go to step 7). If 3-4 shift exceeded one second, go to step 8).
5. Repair 1-2 shift circuit. Inspect for leaking, rolled or cut 1-2 accumulator piston or 2nd clutch piston seals. Inspect for burned or damaged 2nd clutch plates, broken or out of position 2nd clutch springs, cracked or damaged 2nd clutch piston, leaking or damaged driven sprocket support seals, internal fluid passage leaks, casting porosity or damage, or damaged or out of position gaskets or spacer plate.
6. Inspect for slipping forward clutch, cracked or damaged driven sprocket support, damaged 2nd roller clutch or sprag clutch or 2nd roller clutch or sprag clutch not holding. Repair or replace components as necessary, then go to step 9).
7. Repair 2-3 shift circuit. Inspect for leaking, rolled or cut 2-3 accumulator or direct clutch piston seals, burned or damaged direct clutch plates, broken or out of position direct clutch springs, cracked or damaged direct clutch piston, leaking or damaged driven sprocket support seals, cracked or damaged driven sprocket support, damaged sprag clutch or sprag clutch not holding. Check for internal fluid passage leaks, casting porosity or damage, or damaged or out of position gaskets or spacer plate. Repair or replace components as necessary, then go to step 9).
8. Repair 3-4 shift circuit. Inspect for leaking, rolled or cut 3-4 accumulator piston or intermediate/4th servo piston seals and burned, damaged, slipping or out of position intermediate/4th band. Check for internal fluid passage leaks, casting porosity or damage, or damaged or out of position gaskets or spacer plate. Inspect direct clutch for slipping, damaged or seized intermediate/4th servo pin, damaged intermediate/4th servo piston or cracked or leaking intermediate/4th servo cover. Repair or replace components as necessary, then go to next step.
9. Because PCM commands maximum line pressure and does not inhibit TCC engagement for DTC P1811, torque converter may need replacement due to possible "ballooning". Check torque converter for "ballooning" and replace as necessary, then go to next step.
10. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P1811". Drive vehicle in D4 to obtain 1-2, 2-3 and 3-4 upshift. Shift times must be less than one second. If DTC P1811 is not present, repair is complete. If DTC P1811 is still present, repeat test.

Question owner about vehicle overloading, exceeding trailer towing limit or towing in overdrive. If after several unsuccessful attempts to gain accurate shift times and an adapt can be made, reset adapts and operate vehicle to assure proper shifting.

DTC P1860: TCC PWM SOLENOID CIRCUIT (ELECTRICAL MALFUNCTION)

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS .

Torque Converter Clutch (TCC) Pulse Width Modulated (PWM) solenoid is a normally closed solenoid used to control apply and release of converter clutch. PCM operates TCC PWM solenoid with a negative duty cycle. When vehicle operating conditions are appropriate to apply TCC, PCM immediately increases duty cycle to about 42 percent. PCM then increases duty cycle to about 90 percent to achieve full TCC apply pressure. When solenoid is commanded on, PCM will detect high voltage. When solenoid is commanded off, PCM will detect low voltage. DTC P1860 will set when PCM detects a continuous open, short to ground or short to voltage in TCC PWM solenoid circuit.

Conditions For Setting DTC P1860

DTC will set under the following conditions

1. System voltage is 9-16 volts.
2. Engine has been running for more than 5 seconds, and is not in fuel shut off mode.
3. TCC duty cycle is less than 10 percent or more than 90 percent.
4. PCM detects an open, short to ground or short to voltage in TCC PWM solenoid circuit within 5 seconds.

PCM performs the following if DTC is set

1. Will light MIL at first failure signal.
2. Inhibits TCC engagement.
3. Freezes shift adapts from being updated.
4. DTC P1860 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. If DTCs P0753 and P0758 are present, go to next step. If DTCs P0753 and P0758 are not present, go to step 3).
2. Remove AUTO TRANS fuse from instrument panel fuse block and inspect fuse. Replace fuse if necessary, and check for short to ground in Pink wire between transaxle 20-pin connector and fuse block. Repair wire as necessary, then go to step 12). If wire is okay, check for short to ground in Red wire between transaxle 20-pin connector and TCC PWM solenoid. Repair wire as necessary, then go to step 12). If fuse is okay, check for open in Pink wire between transaxle 20-pin connector and fuse block, or Red wire between TCC PWM solenoid and transaxle 20-pin connector. Repair wire(s) as necessary, then go to step 12).
3. Turn ignition off. Disconnect transaxle 20-pin connector. Install Jumper Harness (J-39775) to PCM side of transaxle 20-pin connector. Connect a test light between terminal "E" and "T" (Pink wire and Brown wire) of transaxle 20-pin connector. (Scheme 24) Turn ignition switch to ON position. DO NOT start engine. If test light is on, go to next step. If test light is off, go to step 6).
4. Turn ignition off. Disconnect PCM 80-pin connector C2. (Scheme 25) PCM is located below left side of instrument panel, near steering column.
5. On all models, turn ignition switch to ON position. Ensure test light is still connected between terminals "E" and "T" (Pink wire and Brown wire) of transaxle 20-pin connector. If test light is off, replace PCM, the go to step 12). If test light is on, check for short to ground in Brown wire between transaxle 20-pin connector and PCM. Repair wire as necessary, then go to step 12).
6. Using scan tool, command TCC PWM solenoid on and off 3 times. If test light cycles on and off 3 times, go to step 9). If test light does not cycle on and off 3 times, or test light is always off, go to next step.
7. Check for open in Brown wire between transaxle 20-pin connector and PCM. Repair wire as necessary, then go to step 12). If wire is okay, go to next step.
8. Connect test light between ground and terminal "T" (Brown wire) of transaxle 20-pin connector. If test light is off, replace PCM, then go to next step. If test light is on, check for short to battery voltage in Brown wire between transaxle 20-pin connector and TCC PWM solenoid. Repair wire as necessary, then go to step 12).
9. Turn ignition off. Disconnect jumper harness from PCM side of transaxle 20-pin connector and install harness to transaxle side of 20-pin connector. Connect ohmmeter between terminals "E" and "T" (Pink wire and Brown wire) of transaxle 20-pin connector.
10. If resistance is 10-15 ohms, go to next step. If resistance is not 10-15 ohms but is more than 250 ohms, check for open or poor connection in Brown wire and Red wire at connector. Repair wire or connector as necessary, then go to step 12). If resistance is not 10-15 ohms but is less than 250 ohms, go to next step.
11. Connect ohmmeter between ground and terminal "T" (Brown wire) of transaxle 20-pin connector. If resistance is more than 1000 ohms, replace TCC PWM solenoid, then go to next step. If resistance is less than 1000 ohms, check for short to ground in Brown wire between transaxle 20-pin connector and TCC PWM solenoid. Repair wire as necessary, then go to next step.
12. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P1860". Road test vehicle in D4 and increase vehicle speed until TCC applies. Ensure TCC duty cycle is 10-90 percent for more than 5 seconds. If DTC P1860 is not present, repair is complete. If DTC P1860 is still present, repeat test.

Ensure transaxle fluid level is correct. Inspect PCM, transaxle and PWM solenoid connectors for bent, broken or backed out terminals. Check for chafed wire that could short to bare metal or other wiring. Inspect for broken wire inside insulation. Check for moisture or corrosion. If diagnosing for intermittent short or open condition, move wiring harness while observing scan tool for value change.

DTC P1887: TCC RELEASE SWITCH CIRCUIT MALFUNCTION

Note. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK prior to performing diagnostic procedures. For wire terminal locations, see WIRING DIAGRAMS .

Torque Converter Clutch (TCC) release switch is part of Pressure Switch Assembly (PSA) which is mounted to control valve assembly. Normally-closed switch provides a signal to PCM to indicate when TCC is released. This is accomplished by torque converter release fluid pressure acting on switch contact and opening the circuit. When voltage is high on circuit No. 657 (Yellow wire) or No. 1804 (White wire), PCM recognizes TCC is no longer engaged. DTC P1887 will set when PCM detects TCC release switch is open, indicating TCC is not applied, and TCC slip speed indicates TCC is engaged.

Conditions For Setting DTC P1887

DTC will set under the following conditions

1. DTCs P0716 or P0717 (input speed sensor) and P0741 or P0742 (TCC solenoid) are not present.
2. Engine is running.
3. Transaxle position switch is in D4.
4. TCC is commanded on.
5. TCC slip speed is between -20 RPM and 20 RPM.
6. TCC release switch is open.
7. All conditions are met for 8 seconds.

PCM performs the following if DTC is set

1. Will light MIL after 2 consecutive trips with a failure signal.
2. Freezes shift adapts from being updated.
3. Commands maximum line pressure.
4. Inhibits TCC engagement.
5. DTC P1887 will be stored in PCM history.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select "TCC Release Switch" on scan tool. If TCC release switch status on scan tool is closed, go to next step. If TCC release switch status on scan tool is open, go to step 5).
3. Start engine. If TCC release switch status on scan tool is open, go to step 10). If TCC release switch status on scan tool is closed, turn ignition off. Disconnect transaxle 20-pin connector. Turn ignition switch to ON position. DO NOT start engine.
4. If TCC release switch status on scan tool is open, go to step 7). If TCC release switch status on scan tool is closed, check for short to ground in Yellow wire between transaxle 20-pin connector and PCM. Repair wire as necessary, then go to step 11). If wire is okay, replace PCM, then go to step 11).
5. Install Jumper Harness (J-39775) to PCM side of transaxle 20-pin connector. Connect fused jumper between ground and terminal "U" (Yellow wire) of transaxle 20-pin connector.
6. If TCC release switch status on scan tool is closed, go to next step. If TCC release switch status on scan tool is open, check for open in Yellow wire between transaxle 20-pin connector and PCM. Repair wire as necessary, then go to step 11). If wire is okay, replace PCM, then go to step 11).
7. Disconnect jumper harness from PCM side of transaxle 20-pin connector and install harness on transaxle side of 20-pin connector. Connect ohmmeter between ground and terminal "U" (White wire) of transaxle 20-pin connector.
8. If resistance is more than 50 ohms, check for open in White wire between transaxle 20-pin connector and TCC release switch. Repair wire as necessary, then go to step 11). If wire is okay, replace PSA, then go to step 11). If resistance is less than 50 ohms, start engine. If resistance is more than 50 ohms, check for open in White wire between transaxle 20-pin connector and TCC release switch. Repair wire as necessary, then go to step 11). If wire is okay, replace PSA, then go to step 11).
9. If resistance is less than 50 ohms, check for short to ground in White wire between transaxle 20-pin connector and TCC release switch. Repair wire as necessary, then go to step 11). If wire is okay, replace PSA, then go to step 11).
10. Inspect for leaking or cut torque converter "O" ring, blocked channel plate orificed exhaust passage, leaking, cut or improperly installed oil pump bearing and seal assembly seal, valve body-to-spacer plate gasket misaligned, spacer plate-to-channel plate gasket misaligned, channel plate turbine shaft sleeve installed backward or does not fit, blocked valve body spacer plate release exhaust orifice, or cut or missing turbine shaft-to-sprocket seal. Repair component(s) as necessary, then go to next step.
11. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Select "Specific DTC" and enter DTC "P1887". Drive vehicle in D4 to obtain 45 MPH. With TCC commanded on and engaged, TCC release switch status must be closed (no release oil present at switch) for 8 seconds. If DTC P1887 is not present, repair is complete. If DTC P1887 is still present, repeat test.

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

COMPONENT & WIRING HARNESS RESISTANCE CHECK

1. Install Jumper Harness (J-39775) to transaxle 20-pin connector. Using an ohmmeter, measure resistance between specified terminals for each component. (Scheme 24) Compare resistance reading to known values. See «TRANSAXLE COMPONENT RESISTANCE SPECIFICATIONS»(/chevrolet/malibu/v-1996-2000/remont/automatic-trans/#automatic-transaxle-diagnosis-4t40-e-24l) table.
2. If resistance reading is okay, go to next step. If resistance reading is not okay, disconnect wiring harness at component and measure component resistance. Replace component if resistance is not as specified. If resistance is as specified, repair wiring harness between component and 20-pin connector.
3. Measure resistance between ground and each terminal at transaxle 20-pin connector. (Scheme 24) Resistance should be more than 250 k/ohms for each solenoid and more than 10 megohms for input and vehicle speed sensors. Resistance for temperature sensor should be more than 20 megohms and will vary with temperature. If resistance is within specification, problem is intermittent. If resistance is low, disconnect wiring harness at component.
4. Measure resistance between component terminals and ground. If resistance is low, replace component. If resistance is high, inspect wiring harness for short to ground. Repair as necessary.

TRANSAXLE COMPONENT RESISTANCE SPECIFICATIONS

Scheme 24

TRANSAXLE WIRING HARNESS CHECK

1. Install Jumper Harness (J-39775) on transaxle 20-pin connector (transaxle harness side). Using a DVOM and Connector Test Adapter Kit (J-35616), measure resistance between transaxle 20-pin connector terminals "A" and "E" (1-2 shift solenoid). (Scheme 24) If resistance is 24-31 ohms at 212°F (100°C), go to step 3). If resistance is not 24-31 ohms at 212°F (100°C), go to next step.
2. Disconnect transaxle wiring harness connector at 1-2 shift solenoid. (Scheme 24) Measure resistance between 1-2 shift solenoid terminals. If resistance is not 24-31 ohms at 212°F (100°C), replace1-2 shift solenoid. If resistance is 24-31 ohms at 212°F (100°C), go to step 16).
3. Measure resistance between transaxle 20-pin connector terminals "B" and "E" (2-3 shift solenoid). (Scheme 24) If resistance is 24-31 ohms at 212°F (100°C), go to step 5). If resistance is not 24-31 ohms at 212°F (100°C), go to next step.
4. Disconnect transaxle wiring harness connector at 2-3 shift solenoid. (Scheme 24) Measure resistance between 2-3 shift solenoid terminals. If resistance is not 24-31 ohms at 212°F (100°C), replace 2-3 shift solenoid. If resistance is 24-31 ohms at 212°F (100°C), go to step 16).
5. Measure resistance between transaxle 20-pin connector terminals "E" and "T" (TCC PWM solenoid). (Scheme 24) If resistance is 13-15 ohms at 212°F (100°C), go to step 7). If resistance is not 13-15 ohms at 212°F (100°C), go to next step.
6. Disconnect transaxle wiring harness connector at TCC PWM solenoid. (Scheme 24) Measure resistance between solenoid terminals. If resistance is not 13-15 ohms at 212°F (100°C), replace TCC PWM solenoid. If resistance is 13-15 ohms at 212°F (100°C), go to step 16).
7. Measure resistance between transaxle 20-pin connector terminals "C" and "D" (pressure control solenoid). (Scheme 24) If resistance is3-7 ohms at 212°F (100°C), go to step 9). If resistance is not 3-7 ohms at 212°F (100°C), go to next step.
8. Disconnect transaxle wiring harness connector at pressure control solenoid. (Scheme 24) Measure resistance between solenoid terminals. If resistance is not 3-7 ohms at 212°F (100°C), replace pressure control solenoid. If resistance is 3-7 ohms at 212°F (100°C), go to step 16).
9. Measure resistance between transaxle 20-pin connector terminals "S" and "V" (input speed sensor). (Scheme 24) If resistance is 750-835 ohms at 212°F (100°C), go to step 11). If resistance is not 750-835 ohms at 212°F (100°C), go to next step.
10. Disconnect transaxle wiring harness connector at input speed sensor. Measure resistance between sensor terminals. If resistance is not 750-835 ohms at 212°F (100°C), replace input speed sensor. If resistance is 750-835 ohms at 212°F (100°C), go to step 16).
11. Measure resistance between transaxle 20-pin connector terminals "L" and "M" (TFT sensor). (Scheme 24) If resistance is 164-190 ohms at 212°F (100°C), go to step 13). If resistance is not 164-190 ohms at 212°F (100°C), go to next step.
12. Disconnect transaxle wiring harness connector at TFT sensor. TFT sensor is part of pressure switch assembly. (Scheme 24) Measure resistance between sensor terminals. If resistance is not 164-190 ohms at 212°F (100°C), replace TFT sensor. If resistance is 164-190 ohms at 212°F (100°C), go to step 16).
13. Using a DVOM and Connector Test Adapter Kit (J-35616), measure resistance between transaxle case and transaxle 20-pin connector terminals "A", "B", "C", "D", "E" and "T". (Scheme 24) If resistance is more than 250 k/ohms at each terminal, go to next step. If resistance is less than 250 k/ohms at each terminal, replace transaxle wiring harness.
14. Using a DVOM and connector test adapter kit, measure resistance between transaxle case and transaxle 20-pin connector terminals "L" and "M". (Scheme 24) If resistance is more than 20 megohms at each terminal, go to next step. If resistance is less than 20 megohms at each terminal, replace transaxle wiring harness.
15. Using a DVOM and connector test adapter kit, measure resistance between transaxle case and transaxle 20-pin connector terminals "S" and "V". (Scheme 24) If resistance is more than 10 megohms at each terminal, go to next step. If resistance is less than 10 megohms at each terminal, replace transaxle wiring harness.
16. Inspect for high resistance. Check transaxle wiring harness for poor electrical connections at 20-pin connector and at each component connector. Look for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Repair as necessary, then go to step 1). If no problem was found, replace transaxle wiring harness.

Note. Pressure Switch Assembly (PSA) is also referred to as Transaxle Fluid Pressure (TFP) manual valve position switch.

TRANSAXLE FLUID PRESSURE (TFP) MANUAL VALVE POSITION SWITCH

RESISTANCE CHECK

Note. For TFP manual valve position switch terminal identification, see WIRING DIAGRAMS .

1. Install Jumper Harness (J-39775) on transaxle 20-pin connector (transaxle harness side). Using a DVOM and Connector Test Adapter Kit (J-35616), measure resistance between transaxle 20-pin connector terminals "U" and transaxle case. (Scheme 24) If resistance is less than 50 ohms, go to step 3). If resistance is more than 50 ohms, go to next step.
2. Disconnect wiring harness connector at position switch. (Scheme 24) Measure resistance between position switch terminal "D" and position switch housing. If resistance is less than 50 ohms, go to step 14). If resistance is more than 50 ohms, replace position switch.
3. Reconnect position switch connector. Measure resistance between transaxle 20-pin connector terminal "N" and transaxle case. (Scheme 24) If resistance is more than 50 k/ohms, go to step 5). If resistance is less than 50 k/ohms, go to next step.
4. Disconnect wiring harness connector at position switch. (Scheme 24) Measure resistance between position switch terminal "A" and position switch housing. If resistance is more than 50 k/ohms, go to step 14). If resistance is less than 50 k/ohms, replace position switch.
5. Reconnect position switch connector. Measure resistance between transaxle 20-pin connector terminal "R" and transaxle case. (Scheme 24) If resistance is more than 50 k/ohms, go to step 7). If resistance is less than 50 k/ohms, go to next step.
6. Disconnect wiring harness connector at position switch. (Scheme 24) Measure resistance between position switch terminal "B" and position switch housing. If resistance is more than 50 k/ohms, go to step 14). If resistance is less than 50 k/ohms, replace position switch.
7. Reconnect position switch connector. Measure resistance between transaxle 20-pin connector terminal "P" and transaxle case. (Scheme 24) If resistance is more than 50 k/ohms, go to step 9). If resistance is less than 50 k/ohms, go to next step.
8. Disconnect wiring harness connector at position switch. (Scheme 24) Measure resistance between position switch terminal "C" and position switch housing. (Scheme 24) If resistance is more than 50 k/ohms, go to step 14). If resistance is less than 50 k/ohms, replace position switch.
9. Reconnect position switch connector. Start engine and let idle. Set parking brake. Ensure gear selector is in "P" position. Measure resistance between transaxle 20-pin connector terminal "U" and transaxle case. If resistance is more than 50 k/ohms, go to next step. If resistance is less than 50 k/ohms, replace position switch.
10. Place gear selector in "R" position. Measure resistance between transaxle 20-pin connector terminal "P" and transaxle case. If resistance is less than 50 ohms, go to next step. If resistance is more than 50 ohms, replace position switch.
11. Place gear selector in "D" position. Measure resistance between transaxle 20-pin connector terminal "N" and transaxle case. If resistance is less than 50 ohms, measure resistance between transaxle 20-pin connector terminal "R" and transaxle case. If resistance is less than 50 ohms, go to next step. If resistance is more than 50 ohms, replace position switch.
12. Place gear selector in "1" position. Measure resistance between transaxle 20-pin connector terminal "N" and transaxle case. If resistance is less than 50 ohms, go to next step. If resistance is more than 50 ohms, replace position switch.
13. Reconnect position switch connector. Measure resistance between transaxle 20-pin connector terminal "P" and transaxle case. (Scheme 24) If resistance is less than 50 ohms, go to next step. If resistance is more than 50 ohms, replace position switch.
14. Inspect for high resistance. Check transaxle wiring harness for poor electrical connections at 20-pin connector and at position switch. Look for bent, backed out, deformed or damaged terminals. Check for weak terminal tension. Repair as necessary, then go to step 1). If no problem was found, replace transaxle wiring harness.

Scheme 25

Transmission Wiring Diagram. Scheme 26

See also:
• CLUTCH & BAND APPLICATION CHART
• CLEARING TROUBLE CODES
• DTC P0218
• DTC P0502
• DTC P0503
• DTC P0711
• DTC P0712
• DTC P0713
• DTC P0716
• DTC P0717
• DTC P0719
• DTC P0724
• DTC P0730
• DTC P0741
• DTC P0742
• DTC P0748
• DTC P0751
• DTC P0753
• DTC P0756
• DTC P0758
• DTC P1810
• DTC P1811
• DTC P1860
• DTC P1887
• RETRIEVING CODES
• ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK