Torque Converter Clutch (TCC) Circuit Check: Notes

WARNING: This page does not describe the selected car, but rather 24 other vehicles, including the 1992 GMC Yukon, 1992 GMC Vandura Special, 1992 GMC Vandura, 1992 GMC Value Van, and 1992 GMC Suburban. However, it is still accessible from the selected car via links, so may be relevant.

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.