Code P088, TCC Not Disengaging: Action

PCM turn on MIL and freezes shift adapts from being updated. TCC disabled.

PCM turn on MIL.

NOTE: Test numbers refer to numbers on diagnostic chart.

Checks circuit No. 422 (Tan/Black wire) between engine harness connector C129 and PCM connector 3E13 for short to ground.
Isolates short to ground between engine harness or PCM.
Checks circuit No. 422 for short to ground inside transaxle.

Fig 1: Code P088 Schematic, TCC Not Disengaging

Courtesy of GENERAL MOTORS CORP.

Fig 2: Code P088 Diagnostic Flow Chart, TCC Not Disengaging

Courtesy of GENERAL MOTORS CORP.