Scan Tool Testing and Procedures
SRS General Diagnosis / Diagnostic Trouble CodesCaution: In order to avoid deploying the air bag when troubleshooting the Supplemental Restraint System (SRS), use only the equipment specified and the instructions given. Failure to use the specified equipment as instructed could cause air bag deployment, personal injury to you or someone else, or unnecessary SRS repairs.
The SRS Diagnostic System Check SRS Diagnostic System Check must always be the starting point of any SRS diagnosis. The SRS a Diagnostic System Check checks for proper AIR BAG warning lamp operation and checks for SRS Diagnostic Trouble Codes (DTC) using the scan tool. The following describes the difference between current and history DTCs:
Current DTCs - Malfunctions that are presently being detected. Random Access Memory (RAM) stores the current DTCs. Turning the ignition switch to the OFF position erases current DTCs. The presence of a current DTC will cause the supplemental restraint Sensing and Diagnostic Module (SDM) to turn ON the AIR BAG warning lamp.
History DTCs - All malfunctions detected since last clearing of history memory. Electrically Erasable Programmable Read Only Memory (EEPROM) stores the history DTCs. A scan tool clear codes command will erase history DTCs.
Some DTCs are latched and can not be cleared. Latched DTCs will require replacement of the SDM after proper diagnostics.
Use of Special Tools
You should be familiar with the tools listed. You should know how to measure voltage and resistance. Diagnosis requires proper use of the following tools:
- The Scan Tool
- The J 38715-A SRS Driver/Passenger Load Tool
- The J 35616-A Connector Test Adapter Kit
- The J 39200 Digital Multimeter
- The J 38715-96 SRS Shorting Bar Tool