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.

Suspected intermittents or opens at connectors can be detected with diagnostic service probe which permits voltage to be measured on wires without unplugging connectors. Ensure terminals make good connection.
When diagnosing intermittent problems, select MALF HISTORY from Tech 1 scan tester ABS menu. Supplemental data can be used to duplicate problem.

Fig 1: Code 12 - Schematic

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Fig 2: Code 12 - Diagnostic Flowchart (1 Of 3)

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Fig 3: Code 12 - Diagnostic Flowchart (2 Of 3)

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Fig 4: Code 12 - Diagnostic Flowchart (3 Of 3)

Courtesy of GENERAL MOTORS CORP.