Diagnostic Instructions
Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS)
Diagnostic Instructions
The symptom chart can be used to help locate SRS concerns if no DTCs are retrieved and the listed symptoms are observed. Whether or not the listed symptoms are observed, always carry out the following:
1. Run the Self Test to determine what on-demand and continuous memory DTCs are being sensed by the RCM and OCSM.
2. Retrieve all SRS DTCs and fault PIDs stored in the RCM and OCSM memory.
3. If on-demand DTCs are different than continuous memory DTCs, always diagnose the on-demand DTCs first.
A DTC can indicate several concerns. The DTCs are to assist in system diagnosis and are not to be considered definitive. Always refer to the pinpoint test corresponding to the DTC to determine where the concern lies and to repair the concern correctly.
Lamp Fault Codes (LFCs)
This vehicle supports Lamp Fault Codes (LFCs) only when the RCM is in plant mode. A new RCM installed to a vehicle will be in plant mode until:
- Programmable Module Installation (PMI) has been carried out.
- the RCM sees a fault-free SRS (no DTCs present).
If a LFC is present after completing Programmable Module Installation (PMI), a fault is present in the SRS and on-demand DTCs must be retrieved and diagnosed.
Fault PIDs
There are 2 types of fault PIDs that can be reported by the RCM. The first type, considered conventional, has only one level of fault reporting and identifies a specific concern for a given component and points to a particular diagnostic path, example: DTC B1317 (Battery Voltage High).
The second type uses a process within the software of the controller that maps the byte and bit to name a specific device and fault condition. This process is called Bit-mapping and referred to as fault PIDs in the diagnosis of the vehicle. This type does not identify the specific concern or component on the first level of fault reporting, Example: DTC B2293 (Restraint system - Airbag Fault). DTC B2293 can have up to 28 specific on-demand fault PIDs (areas of concern) associated with this DTC.
Those associated fault PIDs are an extension of the information provided by the DTC and are identified by the same DTC number. A scan tool must be used to view DTCs and their fault PIDs. Once a scan tool has retrieved a DTC, use the scan tool to view the fault PIDs. In the diagnostic path, other types of PIDs are sometimes used to determine the root cause (example: resistance or voltage PIDs).
When viewing of fault PIDs has been carried out, the scan tool can display the PIDs associated with that DTC, including the status or state that exists (on-demand [active] DTC) or existed (continuous memory [historic] DTC). Refer to the manufacturer instructions for the scan tool being used on how to view fault PIDs.
Prove Out Procedure
Turn the ignition switch from the OFF to the ON position and visually monitor the air bag warning indicator with all SRS components connected. The air bag warning indicator will light continuously for approximately 6 seconds and then turn off. If an SRS fault is present, the air bag warning indicator will:
- fail to light.
- remain lit continuously.
- flash.
When the ignition is cycled (turned OFF and then ON), the IC module will prove out the air bag warning indicator by lighting for 6 seconds and then turn off. If a current SRS fault exists, the RCM requests illumination of the air bag warning indicator and will remain illuminated for the rest of the key cycle. The RCM will communicate on-demand (current) and continuous (historical) DTCs through the DLC, to the scan tool. If the RCM requests illumination of the air bag warning indicator and the air bag warning indicator does not function, the IC module will automatically activate an audible chime. The chime is a series of 5 sets of 5 tone bursts. If the chime is heard, the SRS and the air bag warning indicator require repair.
The air bag warning indicator may not illuminate until approximately 30 seconds after the ignition switch has been turned from the OFF to the ON position. This is the time required for the RCM to complete the testing of the SRS. If the air bag warning indicator is inoperative and an SRS fault exists, a chime will sound in a pattern of 5 sets of 5 beeps. If this occurs, the air bag warning indicator will need to be repaired before diagnosis can continue.