Supplemental Inflatable Restraint (SIR)

Diagnostic Chart:

Circuit Schematic:

WARNING: During service procedures, be very careful when handling a sensing and diagnostic module (SDM). Never strike or jar the SDM. Never power up the sir system when the SDM is not rigidly attached to the vehicle. All SDM and mounting bracket fasteners must be carefully torqued and the arrow must be pointing toward the front of the vehicle to ensure proper operation of the sir system. The SDM could be activated when powered while not rigidly attached to the vehicle which could cause deployment and result in personal injury.

CIRCUIT DESCRIPTION
The SDM contains a sensing device which converts vehicle velocity changes to an electrical signal. The electrical signal generated is processed by the SDM and then compared to a value stored in memory. When the generated signal exceeds the stored value, additional signal processing is performed and the generated signals are compared to signals stored in memory. When two of the generated signals exceed the stored values or when one of the generated signals exceeds the stored value and the internal SDM sensor closes, the SDM will cause current to flow through the inflator modules deploying the air bags and causing DTC 51 to set.

DTC WILL SET WHEN:
The SDM detects a frontal crash, up to 30 degrees off the centerline of the vehicle, of sufficient force to warrant deployment of the air bags.

ACTION TAKEN:
SDM turns On the AIR BAG warning lamp, records "Crash Data," and sets a diagnostic trouble code.

DTC WILL CLEAR WHEN:
A scan tool "Clear Codes" command is received by the SDM.

DTC CHART TEST DESCRIPTION:
Number(s) below refer to step number(s) on the diagnostic chart.
1. If inflator module(s) has not deployed, DTC 51 may have set falsely.
2. If DTC 51 has set with no signs of frontal impact, the diagnostic trouble code has set falsely.
5. This test checks for an ADM malfunction setting the diagnostic trouble code.
7. This test determines whether the diagnostic trouble code was set inadvertently during diagnosis.
8. When a frontal crash has occurred, it is necessary to perform the indicated procedures to ensure the SIR system is fully functional.


DIAGNOSTIC AIDS

Was the "SIR Diagnostic System Check" performed?

When measurements are requested in this chart, use (Saturn Tool) SA 91114NE DVM with correct terminal adapter from SA 9206Z.