P1651 GMC - Fan 1 Relay Control Circuit
- Fan 1 Relay harness is open or shorted
- Fan 1 Relay circuit poor electrical connection
Output Driver Modules (ODM) are used by Powertrain Control Module (PCM) to turn on current-driven devices needed to control various engine and transaxle functions. Each ODM can control up to 7 outputs, including fan 1 relay, by supplying ground to device PCM is commanding on. ODMs can diagnose each circuit individually.