Diagnostic Aids
When class 2 serial data line is shorted to ground, U1300 will be set. Go to DTC U1300: SERIAL DATA LINE SHORT TO GROUND under DIAGNOSTIC TESTS. When class 2 serial data line is shorted to voltage, U1301 will be set. Go to DTC U1301: SERIAL DATA LINE SHORT TO BATTERY under DIAGNOSTIC TESTS. Disconnecting modules and turning the ignition switch to RUN may cause DTCs to set in these modules. Check for DTCs in each module after repair.