Lamp Fault Codes (LFCs)
Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS)
Lamp Fault Codes (LFCs)
This vehicle supports LFCs only when the RCM is in plant mode. A new RCM installed in 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.
Diagnosing Customer Concerns With On-Demand DTCs
NOTE: Most SRS diagnostic procedures will require depowering and repowering of the SRS. Depowering and repowering requires disconnecting of the battery and removal of the RCM fuse. This reduces the risk of accidental deployment of SRS components while diagnostic procedures are being carried out.
If the air bag warning indicator is reported ON by the customer when the vehicle comes in for service, connect the scan tool and follow the Diagnostic Instruction procedures to identify the concern.
Once the DTC is known, read the Normal Operation of the pinpoint test for the DTC involved.
Using the scan tool with the use of PIDs and active command(s) may be of assistance in diagnosing the concern.
- Follow the depowering procedure as directed.
- Determine the location of components involved in creating the DTC.
- Carry out a thorough visual inspection of:
- components.
- connectors.
- splices and wiring harnesses.
- insulation on conductors.
Diagnosing Customer Concerns With Continuous Memory DTCs
If an air bag warning indicator ON is reported by the customer but is not present when the vehicle comes in for service, follow the Diagnostic Instruction procedures to identify the intermittent DTC.
Once the DTC is known, read the Normal Operation section of the pinpoint test for the DTC involved.
- Follow the depowering procedure as directed.
- Determine the location of components involved in creating the DTC.
- Carry out a thorough visual inspection of:
- components.
- connectors.
- splices and wiring harnesses.
- insulation on conductors.
Refer to the Normal Operations section of the pinpoint test for the DTC involved, which lists the common concerns that relate to the DTC. Concerns are listed according to priority.
Bit-Mapped DTCs
Many of the continuous memory and on-demand DTCs that can be present in the RCM provide general fault information and require accessing the associated bit-mapped PIDs (fault PIDs) to identify the specific concern. DTCs that use fault PIDs are conceptually different from conventional DTCs.
Conventional DTCs identify a specific concern for a given component and point to a particular diagnostic path. In the diagnostic path, PIDs are sometimes used to determine the root cause.
DTCs that use fault PIDs do not identify the specific concern. The DTC identifies the component(s) or type of components in which the concern exists. The next level, fault PIDs, identifies the specific device and fault condition. Fault PIDs are available for both on-demand (active) and continuous memory (historic) DTCs. Those associated PIDs are an extension of the information provided by the DTC and are identified by the same DTC number. Using both DTC and the fault PID is necessary to define the specific fault present (in the same manner as normal DTCs do).
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. Viewing the fault PIDs must be carried out to identify the specific concern that is present. When the 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 DTC) or existed (Continuous Memory Diagnostic Trouble Code (CMDTC)). Refer to the manufacturer's instructions for the scan tool being used on how to view fault PIDs.