TORQUE CONVERTER CLUTCH (TCC) ELECTRICAL DIAGNOSIS
The purpose of the Torque Converter Clutch (TCC) is to eliminate the power loss of the torque converter stage when the vehicle is in a cruise condition. This allows the convenience of an automatic transmission and the fuel economy of a manual transmission.
Fused battery voltage is supplied to the TCC solenoid through the TCC brake switch. The ECM will engage TCC by grounding circuit No. 422 to energize the TCC apply solenoid inside the transmission. The ECM completes circuit whenever TPS exceeds a calibrated value for throttle opening.
Note. Test numbers refer to test numbers on diagnostic chart.
- This test checks for a complete circuit, from ignition switch, through solenoid, and up to test point. Test light should normally be on, since the ECM has not completed circuit.
- This test checks for continuity through TCC brake switch and TCC apply solenoid.
- This test checks for ECM to complete circuit to ground, to energize TCC apply solenoid and engage TCC. Test light should normally go out when ECM completes circuit.
- This test checks for TPS signal. If signal to ECM is correct, fault is in ECM connection or ECM. If TPS voltage signal to ECM is incorrect, proper operation will not occur.
- This test checks for ground in circuit to ECM terminal "C5". Test light should normally be off.
- This test checks for voltage to terminal "A" of TCC connector. Test light should normally be on.
- This test checks for a complete circuit from voltage to ground, via TCC test terminal in ALDL connector. Normally, test light should come on, if harness is good.
