Diagnostic Aids

NOTE: The ANTI-LOCK warning light works in conjunction with a remote light driver in the instrument cluster. Grounding circuit No. 1290 turns warning light off. Opening circuit No. 1290 turns warning light on.

Intermittents or opens suspected to be at connectors can be detected by using diagnostic service probe. Voltage can be read on wires without disconnecting any connectors. When diagnosing intermittent problems, select MALF HISTORY from Tech 1 scan tester ABS menu. Supplemental data can be used to duplicate problem. Check tightness of terminal grip with spare terminal.

Fig 1: CODE 12 M/T Schematic

Courtesy of GENERAL MOTORS CORP.

Fig 2: CODE 12 M/T Flow Chart

Courtesy of GENERAL MOTORS CORP.