DTC P1687: NO CLUSTER BUS MESSAGE 1. Turn ignition on with engine off. Using scan tool, check for DTCs. If DTC SPECIFIC GOOD TRIP counter is displayed and equal to zero, go to next step. If DTC SPECIFIC GOOD TRIP counter is not displayed and equal to zero, go to step 5 . 2. Turn ignition off. Disconnect PCM connectors. PCM is located at passenger's side rear corner of engine compartment. Note location of connectors C1 and C2