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 Self Test to determine what DTCs are currently being sensed by the RCM and OCSM and retrieve all DTCs stored in the RCM memory and OCSM memory.
2. If on-demand DTCs are different than Continuous Memory Diagnostic Trouble Codes (CMDTCs), always repair 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 DTC charts and corresponding pinpoint test (when applicable) to determine where the concern lies and to repair the concern correctly. [1][2]Diagnostic Trouble Code Descriptions
Self-Test/Continuous Memory and Clear DTCs
During vehicle operation, the RCM and OCSM will detect and store both intermittent and hard failure DTCs in memory. The DTC strategy employed by the RCM incorporates a time-out scheme for determining when a fault exists in the system. This requires a fault to exist for up to one minute in the system before the RCM will detect it. For the RCM to determine that a concern no longer exists, the concern must be absent for up to one minute. The actual detection time-outs vary with each DTC.
Once 127 ignition cycles have been recorded by the RCM since the concern was last detected, all RCM CMDTCs will automatically be removed from memory.
Once 128 ignition cycles have been recorded by the OCSM since the concern was last detected, all OCSM CMDTCs will automatically be removed from memory.
Fault PIDs
There are 2 types of fault PIDs that can be reported by the OCSM. 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 (for example, DTC B1317 (Battery Voltage High)). The RCM does not utilize fault PIDs for this vehicle.
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 (for example, DTC B2290 (Occupant Classification System Fault)). DTC B2290 can have up to 3 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 (for 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.
Lamp Fault Codes (LFCs)
This vehicle supports Lamp Fault Codes (LFCs) only when the RCM is in plant mode, a rapid flash of the air bag warning indicator. 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 PMI, a fault is present in the SRS and on-demand DTCs must be retrieved and diagnosed.
Prove Out Procedure
Turn ignition from OFF to the ON position and monitor the air bag warning indicator with all SRS components connected. The IC module will illuminate the air bag warning indicator continuously for approximately 6 seconds and then turn off. If a SRS fault is present, the air bag warning indicator will:
- fail to light.
- remain lit continuously.
- flash.
The air bag warning indicator may not illuminate to indicate a fault is present until approximately 30 seconds after the ignition 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 a 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.