Diagnostic Aids

BCM detects that ignition switch is in RUN position and sends appropriate power mode message to other control modules. Therefore, BCM must be connected to DLC for any other module to communicate with scan tool. When class 2 serial data circuit is shorted to ground, U1300 or U1305 will be set. When class 2 serial data circuit is shorted to voltage, U1301 or U1305 will be set. Disconnecting modules and turning ignition switch to RUN position may cause DTCs to be set in these modules. Check for DTCs in each module upon completion of repairs.