Initial Inspection and Diagnostic Overview

DIAGNOSTIC INSTRUCTIONS - AIR BAG AND SAFETY BELT PRETENSIONER SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
The symptom chart can be used to help locate the air bag supplemental restraint system (SRS) concerns if no diagnostic trouble codes (DTCs) are retrieved and the listed symptoms are observed. Whether or not the listed symptoms are observed, always carry out the following.
1. Retrieve all DTCs stored in the restraints control module (RCM) memory and occupant classification sensor (OCS) module memory. See Retrieve/Clear Continuous DTCs.
2. Run the On-Demand self-test to determine what DTCs are currently being sensed by the RCM and OCS module. See on-demand self-test.
3. If the stored DTCs are different than the current DTCs, always repair the current DTCs first.
4. If memory displays different continuous DTCs than the on-demand self-test, carry out in the following order:
- On-demand self-test.
- Memory (Retrieve/Clear Continuous DTCs).

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.

The SRS diagnostics can be divided into 3 sections.
- Diagnostic test modes
- PID/data monitor and record
- Active command modes

Diagnostic Test Modes
Two menu options are available under the diagnostic test modes.
- Retrieve/Clear Continuous DTCs.
- On-Demand Self-Test.

Retrieve/Clear Continuous DTCs
During vehicle operation, the RCM and OCS module will detects and stores both intermittent and hard fault DTCs in nonvolatile memory. The DTC strategy employed by the RCM/OCS module 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/OCS module will detect it For the RCM/OCS module to determine that a concern no longer exists, the concern must be absent for up to 1 minute. The actual detection time-outs vary with each DTC. The DTCs can be retrieved with the IDS or equivalent tester. Any DTCs stored in the RCM/OCS are displayed on the IDS or equivalent tester along with a brief description of the DTC. If no DTCs are present, the IDS or equivalent tester displays a SYSTEM PASSED message. This option can also be used to clear DTCs from the RCM/OCS memory, as long as the concern no longer exists. Once 128 key cycles have been recorded by the OCS module since the concern was last detected, the DTC will automatically be removed from memory.

Once 75 hours of operation have been recorded by the RCM since the concern was last detected, the DTC will automatically be removed from memory.

To retrieve or clear DTCs, follow these steps.
1. Connect the IDS or equivalent tester to the data link connector (DLC).
2. Turn the ignition switch to the ON position.
3. Follow manufacturer's instructions for the IDS or equivalent tester being used.
4. Select either the RCM or OCS module.

NOTE: Before proceeding with the clearing operation, make note of the DTCs displayed. Once cleared, DTCs cannot be retrieved.

5. All continuous DTCs will be displayed on the screen.
6. Clear the DTCs. After clearing the DTCs, cycle the key OFF, then ON.
- Continuous DTCs that have been cleared will not reoccur as continuous" in the same key cycle. Only new DTCs which were not present before clearing can occur as "continuous" after cleaning.

On-Demand Self-Test
The on-demand self-test option is used to verify that no electrical concerns exist with the air bag SRS. Upon entering the self-test, the restraints control module (RCM) makes an electrical check of each electrical component in the system. When entering the self-test for the occupant classification sensor (OCS) module, and electrical check is made of the OCS system components and circuits as well as functional checks of the OCS system. If a concern is detected, a DTC is displayed on the IDS or equivalent tester with a brief description of the DTC. Concerns detected during the self-test are not stored in memory, unless the same concern was also detected during normal vehicle operation. Run the self-test after any repair to verify that the repair was successful.
To run the on-demand self-test, follow these steps:
1. Connect the IDS or equivalent tester to the data link connector (DLC).
2. Turn the ignition switch to the ON position.
3. Follow manufacturer's instructions for the IDS or equivalent tester being used.
4. Select either the RCM or OCS module.
5. The module will run the on-demand self-test and display on-demand DTCs (reflecting hard system concerns) on the screen.

Bit-Mapped Diagnostic Trouble Codes (DTCs)
Many of the continuous and on-demand DTCs that can be present in the RCM 1 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 devices and fault condition. Fault PIDs are available for both on-demand (active) and continuous (historic) DTCs.

A IDS or equivalent tester must be used to view DTCs and their fault PIDs. Once a IDS or equivalent tester has retrieved a DTC, use the IDS or equivalent tester 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 IDS or equivalent tester can display the PIDs associated with that DTC, including the status or state that exists (on-demand DTC) or existed (continuous DTC). Refer to the manufacturer's instructions for the IDS or equivalent tester being used on how to view fault PIDs.

PID/Data Monitor and Record
The PID/Data monitor and record option allows the IDS or equivalent tester operator to read the state of several parameter IDS (PIDs) to aid in diagnosing the system. PIDs are real time measurements of parameters such as voltages and resistances calculated by the restraints control module (RCM) and occupant classification sensor (OCS) and sent to the IDS or equivalent tester for display. Many of the PIDs supported by the modules are calculated periodically and are, therefore, not true real time readings.

To retrieve PIDs, follow these steps:
1. Connect the IDS or equivalent tester to the data link connector (DLC).
2. Turn the ignition switch to the ON position.
3. Follow manufacturer's instructions for the IDS or equivalent tester being used.
4. Select either the RCM or OCs module.
5. Record all PIDs that are to be retrieved and initiate PID retrieval. PIDs are updated continuously on the display.

Active Commands
Occupant Classification Sensor (OCS) System Reset. This command allows the technician to reset the OCS system. The OCS System Reset active command sets the zero set point of the OCS system.

Inspection and Verification
1. Verify the customer concern by checking the air bag indicator in the instrument cluster. Refer to Prove Out the System.

Visual Inspection Chart:

2. Visually inspect for obvious signs of mechanical or electrical damage using the following chart.
3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.

NOTE: Make sure to use the latest scan tool software release.

4. If the cause is not visually evident, connect the scan tool to the data link connector (DLC).

NOTE: The vehicle communication module (VCM) LED prove out confirms power and ground from the DLC are provided are provided to the VCM.

5. If the scan tool does not communicate with the VCM:
- Check the VCM connection to the vehicle.
- Check the scan tool connection to the VCM.
- See COMMUNICATIONS NETWORK, No power to the scan tool or to the diagnose no communication with the scan tool.

6. If the scan tool does not communicate with the vehicle: See COMMUNICATIONS NETWORK, No response from the powertrain control module (PCM).
7. Carry out the network test
- If the scan tool responds with no communication for one or more modules, see COMMUNICATIONS NETWORK.
- If the network test passes, retrieve and record continuous memory diagnostic trouble codes (DTCs).

8. Clear the continuous DTCs and carry out the self-test diagnostics for the RCM and OCS module.
9. If the DTCs retrieved are related to the concern, see DIAGNOSTIC TROUBLE CODE (DTC) INDEX - RESTRAINTS CONTROL MODULE (RCM). Diagnostic Trouble Code Descriptions
10. If no DTCs related to the concern are retrieve, SYMPTOM TROUBLESHOOTING CHART - AIR BAG SYSTEM. Symptom Related Diagnostic Procedures

Lamp Fault Codes
This vehicle line does not utilize lamp fault codes (LFC).