Diagnostic Instructions

AIR BAG AND SAFETY BELT PRETENSIONER SUPPLEMENTAL RESTRAINT SYSTEM (SRS) DIAGNOSTIC INSTRUCTIONS

The Symptom Chart can be used to help locate Supplemental Restraint System (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.

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 see the pinpoint test corresponding to the DTC to determine where the concern lies and to repair the concern correctly.

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 non-volatile memory. The DTC strategy employed by the RCM incorporates a time-out scheme for determining when a concern exists in the system. This requires a concern 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 continuous memory DTCs will automatically be removed from memory.Once 128 key cycles have been recorded by the OCSM since the concern was last detected, all OCSM continuous memory DTCs 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, example: DTC B1317 (Battery Voltage High). The 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, 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.

Lamp Fault Codes (LFCs)

This vehicle supports 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 the ignition switch from the OFF to the ON position and visually monitor the air bag warning indicator with all SRS components connected. The IC will illuminate the air bag warning indicator continuously for approximately 6 seconds and then turn off. If a 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.