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Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Diagnosis - A/T >> Diagnostic Flow Charts (Cars) >> Code 38, Brake Switch Circuit - 3.3L & 3.8L >> Diagnostic Aids

Diagnostic Aids

A Code 38 in conjunction with a Code 39 or 26 would mean a problem with one or more of the following components.

If brake switch has failed in an open state, TCC will not engage. Code 38 does not turn on SERVICE ENGINE SOON light on all models.

Fig 1: Code 38, Troubleshooting Diagram (3.3L & 3.8L)
G91J07336Courtesy of GENERAL MOTORS CORP.