CHART C-8, TORQUE CONVERTER CLUTCH ELECTRICAL DIAGNOSIS - 3.1L PFI A & J BODIES (2 OF 2)
The 2nd gear signal switch in this vehicle should be open in 2nd and 3rd gear. ECM uses this 2nd gear signal to disengage TCC when going into a downshift. The 3rd gear switch should be open in 3rd gear. (Схема №170)through (Схема №191).
CHART C-8A, TORQUE CONVERTER CLUTCH FUNCTIONAL CHECK - 1992 3.8L PFI (VIN 1)
When solenoid coil is activated, TCC is applied which results in a straight through mechanical coupling from engine to wheels. When solenoid coil is deactivated, TCC is released which allows torque converter to operate in conventional manner. PWN solenoid varies hydraulic pressure to make locking and unlocking of TCC smoother. TCC will engage under the following conditions
- Engine is warmed up.
- Vehicle speed above a calibrated value of about 28 MPH.
- Throttle position not changing, indicating a steady speed.
- Brake switch is closed. NOTE: Test numbers refer to test numbers on diagnostic chart. This test determines whether fault is caused by a bad solenoid or control circuit. This test checks availability of voltage on circuit No. 420. This test checks PCM's capability to pulse PWM solenoid on and off. Electrical circuits have checked out okay. Refer to appropriate AUTO TRANS DIAGNOSIS article for hydraulic and mechanical diagnosis.
TORQUE CONVERTER CLUTCH CIRCUIT CHECK - LT. TRUCK
The automatic transmission TCC eliminates power loss of torque converter stage when vehicle is in a cruise condition. This allows the convenience of the automatic transmission, and fuel economy of a manual transmission.
Fused battery ignition is supplied to the TCC solenoid, located inside valve body, to shift a spool valve in order to modulate pressure to the TCC.
The PCM/TCM will engage TCC by grounding circuit No. 422 to energize the solenoid.
TCC will engage under the following conditions
- Vehicle speed is greater than 30 MPH (48 km/h).
- Engine at normal operating temperature greater than 149°F (65°C).
- Transmission at normal operating temperature of 195°F 91°C).
- Throttle position sensor output is not changing, indicating a steady road speed.
- Brake switch is closed.
- 4th gear is indicated.
- No codes are stored. NOTE: Test numbers refer to test numbers on diagnostic chart. This step checks for a shorted internal transmission harness or TCC solenoid . This step verifies power supply to the TCC solenoid. This step checks circuit No. 422 for a short to ground. This step checks PCM/TCM s ability to control the TCC solenoid. If bidirectional Scan tester is not available, TCC may be activated by grounding ALDL test terminal "B" with ignition on and engine off.