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Home >> GMC >> 1999 >> Forward Control 6.5 F, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Tests W/Codes - DTC P1537-U1193 >> DTC P1641 >> DTC P1641: A/C Relay Control Circuit (3.1L "W" Body) >> Circuit Description
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Circuit Description

Output Driver Modules (ODMs) are used by Powertrain Control Module (PCM) to turn on current driven devices that are needed to control various engine and transaxle functions. Each ODM can control up to 7 separate outputs by grounding the device that PCM is commanding on. ODMs can diagnose each output circuit individually. DTC P1641 indicates an improper voltage level has been detected on Malfunction Indicator Light (MIL) driver circuit.

DTC will set when ignition is on, improper voltage level detected on output circuit controlling A/C compressor control relay and conditions are present for at least 30 seconds.