U1300 Serial Data Line Class 2 Shorted to Ground - SRS

CIRCUIT DESCRIPTION
While the ignition switch is in the RUN position, The inflatable restraint Sensing and Diagnostic Module (SDM) sends messages to other module communicating on the Serial Data Line Class 2. The SDM monitors the Serial Data Line Class 2 (CKT 1807) on terminals 5 and 17 for shorts to voltage and shorts to ground. For more detailed information about the data lines, refer to Computer System Diagnosis.

CONDITIONS FOR SETTING THE DTC
The SDM detects a short to ground at terminals 5 or 17.

ACTION TAKEN WHEN THE DTC SETS
The SDM sets (a) diagnostic trouble code. The SDM does NOT turn on the AIR BAG warning lamp for this DTC. Other SIR DTCs will set that turn the AIR BAG warning lamp ON when a malfunction occurs on the Serial Data Line Class 2.

CONDITIONS FOR CLEARING THE DTC
Current DTC One of the following must occur to clear the DTC:
- The ignition switch is turned OFF.
- The SDM does NOT detect a short to ground at terminals 5 and 17.
^ History DTC.
- You issue a scan tool CLEAR CODES command.
- 250 malfunction-free ignition cycles have occurred.

DIAGNOSTIC AIDS
If DTC U1300 is set you must isolate CKT 1807 and determine where a short to ground is occurring. Disconnecting modules on the Serial Data Line Class 2 and check each individual circuit is the fastest way to find the short. It is highly unlikely that the inflatable restraint Sensing and Diagnostic Module (SDM) will set a State Of Health (SOH) message if the SDM is faulty. Other State Of Health (SOH) DTCs may set in addition to DTC U1300. These DTCs should clear once the short-to-ground condition is repaired.