Automatic Transaxle Diagnosis - 3t40 Buick Skylark VII

APPLICATION

3T40 APPLICATION

Note. This article contains electronic control self-diagnostic information for 1996 transaxle only. Self-diagnostic information for 1995 transaxle is not available.

DESCRIPTION & OPERATION

Powertrain Control Module (PCM) monitors various inputs to control transaxle Torque Converter Clutch (TCC) operation. PCM receives input information from sensors, switches, solenoids and other components. PCM will control TCC apply and release. PCM also includes on-board self-diagnostics. This helps identify which parts or circuits may need further testing.

PCM

On "A" and "L" bodies, PCM is located under passenger side of instrument panel. On "J" body, PCM is located forward of right front wheel housing, behind front fascia cavity splash shield. On all models, PCM utilizes 3 different colored 32-pin connectors. 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 TCC operation based on coolant 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 the ENGINE PERFORMANCE section.

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

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

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

ELECTRONIC SELF-DIAGNOSTICS

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

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

RETRIEVING CODES

Note. Stored DTCs may be retrieved from PCM memory using a factory recommended Tech 1 scan tool or aftermarket scan tool. DTCs CANNOT be retrieved by grounding 16-pin Data Link Connector (DLC). Plugging scan tool into DLC, located under instrument panel, enables user to read DTCs and check voltages in system on serial data line.

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

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

TROUBLE CODE DEFINITIONS

Note. Only transaxle-related trouble codes are listed. For engine-related DTCs, see appropriate TESTS W/CODES article in the ENGINE PERFORMANCE section. These DTCs pertain to engine performance and must be repaired first, as engine performance and related component signals will affect transaxle operation and diagnosis.

PCM TROUBLE CODE DEFINITIONS

HARD OR INTERMITTENT TROUBLE CODE DETERMINATION

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

1. Enter diagnostic mode. See «RETRIEVING CODES»(/buick/skylark/vii-1992-1998/remont/automatic-trans/#automatic-transaxle-diagnosis-3t40__retrieving-codes) . Read and record all stored DTCs. Exit diagnostic mode and clear trouble codes. See «CLEARING TROUBLE CODES»(/buick/skylark/vii-1992-1998/remont/automatic-trans/#automatic-transaxle-diagnosis-3t40__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.

DIAGNOSTIC TESTS

Note. Diagnostic tests only apply to 1996 transaxle.

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

Diagnostic Aids

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

ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK

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

The OBD System Check determines

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

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

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

P0502, VEHICLE SPEED SENSOR CIRCUIT (LOW INPUT)

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

Circuit Description

Vehicle speed is signaled to PCM by Vehicle Speed Sensor (VSS). Sensor is a Permanent Magnet (PM) generator mounted to transaxle case. 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 this signal to calculate vehicle speed and when to apply TCC. DTC P0502 detects a low vehicle output speed when vehicle has high engine speed in drive gear.

Conditions For Setting DTC P0502

DTC will set under the following conditions

1. Transaxle is in drive.
2. DTCs P0107 or P0108 (MAP sensor), or P0122 or P0123 (throttle position) are not present.
3. Throttle position angle is 18-50 percent.
4. MAP is between zero and 4.4 psi (30 kPa).
5. Engine speed is 2950-4800 RPM.
6. Output speed is 2 MPH or less.
7. All conditions are met for 2 seconds.

DTC P0502 will be stored in PCM history. MIL will light after 2 consecutive ignition cycles.

Diagnostic Procedures

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test. Raise and support vehicle. CAUTION: To prevent damage to drive axles, support lower control arms in normal horizontal position.
2. Start engine and let idle. Shift gear selector to "D" position. 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 engine off. Disconnect Purple PCM 32-pin connector. On "A" and "L" bodies, PCM is located under passenger side of instrument panel. On "J" body, PCM is located forward of right front wheel housing, behind front fascia cavity splash shield. Connect voltmeter between PCM connector terminals No. 7 and 8 (Purple wire and Yellow wire). Select AC volts on voltmeter. Rotate front wheels and observe voltmeter. If voltage is more than .5 volts, go to step 5). If voltage is less than .5 volts, go to next step.
4. Connect an ohmmeter between PCM connector terminals No. 7and 8 (Purple wire and Yellow wire). If resistance is 139-376 ohms, go to next step. If resistance is not 139-376 ohms, disconnect Vehicle Speed Sensor (VSS). Connect a jumper wire between VSS connector terminals. If resistance is not 0.5 ohm or less, check for short to ground or open in Yellow wire. Repair wire as necessary, then go to step 7). If wire is okay, replace PCM, then go to step 7). If resistance is 0.5 ohm or less, replace VSS, then go to step 7).
5. Reconnect PCM connector. Disconnect VSS connector at transaxle. Connect voltmeter between ground and terminal "A" (Yellow wire) of speed sensor harness connector. Select DC volts on voltmeter. Turn ignition switch to ON position. DO NOT start engine.
6. If voltmeter displays less than 4.5 volts, check for short to ground or open in Yellow wire. Repair wire as necessary, then go to step 7). If wire is okay, replace PCM, then go to step 7). If voltmeter displays more than 4.5 volts, connect test light between battery voltage and speed sensor connector terminal "B" (Purple wire). If test light is on, check for latest PROM calibration change or incorrect calibration. Repair as necessary. If test light is off, check for open in Purple wire. 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 "P0502". Operate vehicle faster than 2 MPH for 2 seconds. If DTC P0502 is not present, repair is complete. If DTC P0502 is still present, repeat test.

Check for damaged speed sensor or rotor teeth. Check for Electromagnetic Interferences (EMI) induced on Purple and Yellow wires by misrouted wiring harness. Check for loose speed sensor mounting or poor sensor connection at PCM. Check for possible 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 possible intermittent short or open condition, move wiring harness while observing scan tool for value change. Inspect for damaged speed sensor or transaxle rotor teeth.

P0719, BRAKE SWITCH CIRCUIT LOW INPUT (SWITCH STUCK ON)

Note. Perform 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 detects an open (stuck on) brake switch during acceleration.

Conditions For Setting DTC P0719

DTC will set under the following conditions

1. DTC P0502 (vehicle speed sensor) is not present.
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.
3. Conditions must occur 7 times with brake switch on for 15 minutes without a brake switch status change of 2 seconds.

DTC P0719 will be stored in PCM history. MIL will not light when fault is set and PCM inhibits TCC engagement.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select "TCC Brake Switch" on scan tool. Disconnect brake switch connector. Connect fused jumper between brake switch connector terminals. If brake switch status on scan tool changes from on to off, go to step 4).
3. If brake switch status on scan tool does not change from on to off, remove and inspect appropriate fuse from fuse block. See «WIRING DIAGRAMS»(/buick/skylark/vii-1992-1998/remont/automatic-trans/#automatic-transaxle-diagnosis-3t40) . Replace fuse if necessary and check for short to ground in Pink wire (Brown wire on "A" body) 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 2 seconds or more. If DTC P0719 is not present, repair is complete. If DTC P0719 is still present, repeat test.

Check brake switch for correct adjustment. Check for correct and/or updated PROM calibration. Inspect wiring for poor connections at PCM and at brake switch connector. Check for possible 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 possible intermittent short or open condition, move wiring harness while observing scan tool for value change.

P0724, BRAKE SWITCH CIRCUIT HIGH INPUT (SWITCH STUCK OFF)

Note. Perform 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 detects a closed (stuck off) brake switch during deceleration.

Conditions For Setting DTC P0724

DTC will set under the following conditions

1. DTC P0502 (VSS) is not present.
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.
3. Conditions must occur 7 times without a brake switch status change.

DTC P0724 will be stored in PCM history. MIL will not light when fault is set and PCM inhibits TCC engagement.

1. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record failure records for reference. Data will be lost when DTCs are cleared later in this test.
2. Select "TCC Brake Switch" on scan tool. Disconnect brake switch connector. If brake switch status on scan tool changes from off to on, replace brake switch, then go to next step. If brake switch status on scan tool does not change from off to on, 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 2 seconds or more. If DTC P0724 is not present, repair is complete. If DTC P0724 is still present, repeat test.

Check brake switch for correct adjustment. Check for correct and/or updated PROM calibration. Inspect wiring for poor connections at PCM and at brake switch connector. Check for possible 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 possible intermittent short or open condition, move wiring harness while observing scan tool for value change.

P0742, TCC CIRCUIT INOPERATIVE (STUCK ON)

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

Power is supplied to Torque Converter Clutch (TCC) solenoid from fuse panel through Pink wire. From solenoid, ground path is interrupted by normally open 3rd clutch pressure switch. PCM controls activation of solenoid by grounding circuit through internal switch in PCM. Although PCM may command TCC on, converter clutch will not apply until 3rd clutch fluid (3rd clutch engaged) closes pressure switch to complete circuit. When PCM determines conditions are correct, circuit will be grounded through PCM, activating solenoid. When solenoid is on, exhaust fluid is blocked, which moves converter clutch control valve to applied position. This provides fluid pressure to engage TCC. DTC P0742 detects low TCC slip speed when TCC is commanded off.

Conditions For Setting DTC P0742

DTC will set under the following conditions

1. DTC P0122 or P0123 (throttle position), or P0502 (vehicle speed sensor) are not present.
2. Engine speed is 1300-3300 RPM.
3. TCC is commanded off.
4. Throttle position angle is 18-60 percent.
5. Speed ratio is .98-1.41.
6. Slip speed is -20 to 20 RPM for 5 seconds.
7. Vehicle speed is 35-65 MPH.
8. All conditions are met for 3 consecutive times in 2 ignition cycles.

DTC P0742 will be stored in PCM history. MIL will light after 2 ignition cycles with failure present. PCM will inhibit TCC engagement.

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. Turn ignition off. Disconnect transaxle wiring harness connector. Drive vehicle in D3 at a steady throttle position angle more than 18 percent to 40 MPH or more. Record TCC slip speed when transaxle is in 3rd gear with TCC engaged. Select snap shot mode on scan tool. Record TCC slip speed. If TCC slip speed is more than -20 to 20 RPM, go to next step. If TCC slip speed is not more than -20 to 20 RPM, go to step 6).
3. Turn ignition off. Connect test light between Pink wire and Tan/Black wire on engine side of transaxle wiring harness connector. Turn ignition switch to ON position. If test light is not on, go to next step. If test light is on, check for short to ground in Tan/Black wire between PCM and transaxle wiring harness connector. Repair wire as necessary, then go to step 7). If wire is okay, replace PCM, then go to step 7).
4. Remove transaxle side cover. Disconnect Black wire from 3rd clutch pressure switch. Connect ohmmeter from Pink wire of transaxle wiring harness connector to Black wire lead. If resistance is not 19-31 ohms, go to next step. If resistance is 19-31 ohms, go to step 6).
5. Check wiring from TCC solenoid to 3rd clutch pressure switch for short to ground. Repair wire as necessary, then go to step 7). If wire is okay, replace TCC solenoid, then go to step 7).
6. Check for stuck closed (not exhausting) TCC solenoid due to sediment or mechanical failure. Repair as necessary, then go to next step. If solenoid is okay, check for malfunction in converter clutch control valve due to sediment, binding or mechanical failure. Repair as necessary, then go to next step. If valve is okay, check for stuck on (mechanically applied) TCC. Repair 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 "P0742". Drive vehicle in D3 with throttle position angle steady at 30 percent to 55 MPH. TCC slip speed must be 150-2000 RPM for 5 seconds. If DTC P0742 is not present, repair is complete. If DTC P0742 is still present, repeat test.

If vehicle stalls repeatedly, TCC is stuck on.

P1870, TRANSAXLE COMPONENT SLIPPING

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

PCM monitors Torque Converter Clutch (TCC) slip speed by calculating difference between engine speed and transaxle output speed. In D3 drive range with TCC engaged, engine speed should closely match transaxle output speed. DTC P1810 detects excessive TCC slip when TCC is engaged.

Conditions For Setting DTC P1870

DTC will set under the following conditions

1. DTCs P0122 and P0123 (throttle position), or P0502 (vehicle speed sensor) are not present.
2. Engine speed is 2000-3300 RPM.
3. MAP is 2.9-8.9 psi (20.3-61.5 kPa).
4. Throttle position angle is 13-35 percent.
5. TCC is on for 5 seconds or more.
6. TCC slip speed is 150-1000 RPM for 10 seconds.
7. Speed ratio is .98-1.34.
8. Vehicle speed is 40-65 MPH.
9. All conditions are met for 3 TCC cycles.

DTC P1870 will be stored in PCM history. MIL will light at first failure signal and PCM will inhibit TCC engagement.

1. Ensure fluid level is correct. Inspect manual linkage for misadjustment or binding. Inspect throttle valve cable for misadjustment, binding or broken cable. Repair components as necessary, then go to step 9).
2. Check for low line pressure. See LINE PRESSURE TEST in 3T40 OVERHAUL article. If line pressure is within specification, go to step 6). If line pressure is not within specification, go to next step.
3. Check for restricted oil filter or missing or damaged filter seal. Check for missing pressure relief valve check ball. Check for damaged pressure relief valve or pressure regulator valve springs. Check pressure regulator valve for nicks or scored surface. Check for sticking pressure regulator valve. Check oil pump seals for wear or damage. Check for stuck oil pump slide, vane or drive pump damage. Repair components as necessary, then go to step 9). If components are okay, go to next step.
4. 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.
5. Drive vehicle in D3 with TCC engaged. Record TCC slip speed when transaxle is in 3rd gear with TCC engaged. Select snap shot mode on scan tool. Record TCC slip speed. When TCC is engaged, TCC slip speed should be more than 200 RPM. If RPM is as specified, go to next step. If RPM is not as specified, see Diagnostic Aids.
6. Ensure TCC solenoid check ball is seating properly. Ensure converter clutch control valve is not stuck in off position. Repair components as necessary, then go to step 9). If components are okay, go to next step.
7. Check for worn or damaged turbine shaft seal. Check for damaged torque converter. Repair as necessary, then go to step 9). If components are okay, check direct clutch for missing No. 5 check ball, damaged driven sprocket support seals, burned clutch plates, sticking exhaust check ball, or damaged, worn or missing piston seals. Repair components as necessary, then go to step 9). If components are okay, go to next step.
8. Check forward clutch for restricted spacer plate orifice, burned clutch plates, or worn or damaged piston seals. 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 "P1870". Drive vehicle in D3 with throttle position angle at 13-35 percent and vehicle speed at 40-55 MPH with TCC commanded on. TCC slip speed must be between -20 and 40 RPM for 5 seconds. If DTC P1870 is not present, repair is complete. If DTC P1870 is still present, repeat test.

Verify final drive ratio is correct for specific vehicle. Check for vehicle overloading or trailer towing beyond vehicle capacity (if applicable).

COMPONENT & WIRING HARNESS RESISTANCE & VOLTAGE CHECK

1. Disconnect transaxle wiring harness connector. Turn ignition switch to ON position. Using a DVOM, measure voltage between ground and Pink wire terminal at engine side of transaxle wiring harness connector. Voltage should be 12 volts. If voltage is as specified, go to next step. If voltage is not as specified, repair fuse or wiring as necessary.
2. Turn ignition off. Using an ohmmeter, measure resistance at transaxle side of wiring harness connector between TCC solenoid terminal "A" (Pink wire) and 3rd gear pressure switch terminal "D" (Tan/Black wire). Resistance should be 19-31 ohms.
3. If resistance is as specified, go to next step. If resistance is not as specified, 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 transaxle wiring harness connector.
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.

1995 "A" Body - 2.2L (Century, Cutlass Ciera & Cutlass Cruiser) Wiring Diagram. Scheme 201

1995 "J" Body - 2.2L (Cavalier & Sunfire) Wiring Diagram. Scheme 202

1995 "L" Body - 2.2L (Beretta & Corsica) Wiring Diagram. Scheme 203

1995 "N" Body - 2.3L (Achieva, Grand Am & Skylark) Wiring Diagram. Scheme 204

1995 "U" Body - 3.1L (Lumina APV, Silhouette & Trans Sport) Wiring Diagram. Scheme 205

1996 "A" Body - 2.2L (Century & Cutlass Ciera) Wiring Diagram. Scheme 206

1996 "J" Body - 2.2L (Cavalier & Sunfire) Wiring Diagram. Scheme 207

1996 "L" Body - 2.2L (Beretta & Corsica) Wiring Diagram. Scheme 208

See also:
• COMPONENT TESTS
• CLEARING TROUBLE CODES
• P0502
• P0719
• P0724
• P0742
• P1870
• RETRIEVING CODES