DTC P0742 - TCC System Stuck On
Circuit Description
The torque converter clutch (TCC) solenoid is used to apply and release the TCC. The TCC can be applied in all forward gears. The powertrain control module (PCM) controls TCC by pulse width modulating (PWM) an internal driver that pulls the solenoid circuit to ground. When the TCC solenoid is commanded ON, circuit grounded, the TCC is applied, which works opposite to all other 4 transaxle solenoids. The TCC solenoid circuit is monitored for low and high voltage faults. The PCM uses the crankshaft position sensor (CKP) and input speed sensor (ISS) to calculate RPM slip across torque converter. The PCM will use this information to determine torque converter clutch (TCC) slip. DTC P0742 sets when the TCC solenoid is commanded OFF and engine speed equals input shaft speed, indicating TCC is locked.
DTC Parameters
DTC P0742 will set if speed difference across torque converter is less than 84 RPM, indicating TCC stuck ON, when:
| • | The TCC has been commanded OFF for longer than 0.25 seconds. |
| • | The condition exists longer than 4 seconds (2001)*. |
| • | The condition exists for longer than 4 seconds, 1 minute is allowed to elapse, then condition exists again for longer than 4 seconds (2000). |
| • | The engine speed is less than 3,200 RPM. |
| • | The input speed is between 224-2,800 RPM. |
| • | The engine torque is greater than 100 N·m (74 lbs ft). |
| • | DTCs P0336, P0716 or P0717 have not been set. |
DTC P0742 diagnostic runs continuously when the above conditions have been met.
DTC P0742 is a type A DTC for 2000, type B DTC for 2001.*
*Applicable to vehicles built after June 2000.
Diagnostic Aids
Important: If DTCs P0740, P0743, or P0789 is set, diagnose that DTC first. A diagnosed TCC solenoid circuit DTC may have caused DTC P0742 to set.
Refer to Part Description for component location and description.
Ensure that the TCC solenoid is not intermittently sticking. Audible sound should be similar for all solenoids. A muffled tone indicates the need for replacement.
An intermittent short to ground on circuit 422 will cause the TCC to be constantly applied. Use scan tool to command TRANS. SOLENOID POWER ON, while monitoring the TCC SOLENOID - LOW VOLT or TCC SOLENOID - OPEN test. Wiggling wires while monitoring the test may locate a problem.
If the TCC is stuck ON, engine will stall in drive when coming to a stop. After engine has started and a drive gear is selected, transaxle will start in 3rd or 4th gear.
TCC solenoid resistance: 3.8-7.2 ohms
Nominal value: 4.5 ohms at 68°F
