Code 86 - Analog/Digital Error (3.1L CALIF. "W" Body): Notes
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If any other codes are present, use those charts first. The Analog/Digital (A/D) multiplexer chip is an internal part of the ECM. Some ECM sensor inputs lead to the A/D multiplexer. If any one of them shorts to battery voltage for more than 15 seconds, the A/D error diagnostic code will set, resulting in a Code 86.