Supplemental Inflatable Restraint (SIR)

When measurements are requested in this chart, use SA 91114NE DVM with correct terminal adapter from SA 9206Z. When a check for proper connection is requested, refer to "Intermittents and Poor Connections." When a wire connector or terminal repair is requested, use the proper repair parts and refer to "Wiring Repair."

CAUTION: BEFORE PERFORMING DIAGNOSTICS, THE IGNITION SWITCH MUST BE IN THE "OFF" POSITION FOR 10 MINUTES (REFER TO DISABLING AND ENABLING PRECAUTIONS).

NOTICE: Perform "SIR DIAGNOSTIC SYSTEM CHECK" before proceeding with this chart. SIR Diagnostic System Check

CIRCUIT DESCRIPTION
When the ignition switch is turned On, the Sensing and Diagnostic Module (SDM) will perform tests to diagnose critical malfunctions within itself. Upon passing these tests "Ignition 1," VLR, and deployment loop voltages are measured to ensure they are within their respective normal voltage ranges. The SDM then proceeds with the "Current Source Diagnostics. Passenger Side LO" terminal A4 is grounded through a resistor and the passenger current source connected to "Passenger Side HI" terminal Al allows a known amount of current to flow. After "Current Source Diagnostics" are completed the SDM removes the low resistance ground from "Passenger Side LO" and switches the driver current source at "Passenger Side HI." The SDM then measures the voltage at "Passenger Side HI" and "Passenger Side LO" during "Continuous Monitoring." By monitoring the voltage difference between "Passenger Side HI" and "Passenger Side LO" the SDM calculates the combined resistance of the passenger inflator module, harness wiring circuits 1403 and 1404 and connector terminal contact.

DTC WILL SET WHEN:
The calculated combined resistance of the passenger inflator module, harness wiring circuits 1403 and 1404 and connector terminal contact, is greater than 500 ohms for 500 milliseconds during "Current Source Diagnostic" or "Continuous Monitoring."

ACTION TAKEN:
SDM turns On the AIR BAG telltale lamp and sets DTC 17. DTC 17 takes precedence over DTCs 15, 16, 18, 21, 22 and 24.

DTC WILL CLEAR WHEN:
The voltage difference between "Passenger Side HI" terminal A1 and "Passenger Side LO" terminal A4 is less than 100 ohms for 500 milliseconds during "Continuous Monitoring." Or, the malfunction is no longer occurring an 3 the ignition switch is turned Off.

DTC CHART TEST DESCRIPTION:
Number(s) below refer to step number(s) on the diagnostic chart.
Step 1. This test determines whether the malfunction is in the passenger inflator module circuitry or in the SDM wiring harness circuitry.
Step 2. This test determines whether the malfunction is due to a high resistance in circuit 1403.
Step 3. This test determines whether the malfunction is due to a high resistance in circuit 1404.

DIAGNOSTIC AIDS:
An intermittent condition is likely to be caused by a poor connection at the passenger inflator module harness connector terminal A or B, SDM terminals A1 or A4, or an open in circuit 1403 or circuit 1404.