Chart C8A - 700-4R TCC (F Body)

The purpose of automatic transmission/transaxle torque converter clutch feature is to eliminate power loss of torque converter stage when vehicle is in cruise condition. This allows convenience of automatic transmission/transaxle and fuel economy of a manual transmission. Fused battery ignition is supplied to TCC solenoid through brake switch, and transmission 3rd gear apply switch. The ECM will engages TCC by grounding circuit No. 422 to energize solenoid.

TCC will engage when vehicle speed is above 20-22 MPH, engine at normal operating temperature (above 158°F/70°C), throttle position sensor output not charging (indicating a steady road speed), transmission 3rd gear switch closed, and brake switch closed.

1. Checks continuity through brake switch, TCC solenoid, and 4-3 downshift switch.
2. Checks capability of ECM to energize solenoid. Grounding diagnostic connector should energize relay and cause light to go out.
3. This test bYpasses TCC solenoid and 4-3 switch and checks for an open or short in circuit No. 422.
4. Solenoids are turned on or off by ECM internal electronic switches called drivers. Each driver is part of a group of 4 called quaDdrivers. Failure of one can damage another driver within a set. Solenoid coil resistance must measure more than 20 ohms. Less resistance will cause early failure of ECM driver. Using an ohmmeter, check solenoid coil resistance before installing a replacement ECM.