Supplemental Inflatable Restraint (SIR)

CIRCUIT DESCRIPTION
The air bag indicator Circuit consists of the instrument cluster. air bag indicator. junction block 1 and the center sensor assembly. Voltage is applied to the air bag indicator (inside the instrument cluster) at all times. When the ignition switch is turned to "ACC" or "ON." the center sensor assembly grounds the LA CKT, terminal "B6" for six seconds while it performs the "Primary Check." This causes the air bag indicator to be illuminated. If the center sensor assembly detects a fault within the SRS, it will ground the LA CKT, illuminate the air bag indicator, open the safety circuit (preventing SRS operation) and store a DTC.

If there is a fault within the air bag indicator circuit. the air bag indicator may not be able to illuminate. Therefore, it is important to diagnose and repair any fault(s) within the air bag indicator circuit before continuing with other SRS diagnosis.

FAILURE CONDITIONS
DTC 22 will set if there is an open or a short to ground in the air bag indicator circuit. If there is an open in the circuit, the air bag indicator may not be illuminated.

ACTION TAKEN
The center sensor assembly will attempt to illuminate the air bag indicator and will open the safety circuit preventing SRS operation.

TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test checks for a good ECU-B fuse.
2. This test checks for an open in the power feed to the ECU-B fuse.
3. This test determines whether the fault is due to a short to ground in the SW CKT or a faulty center sensor assembly.
4. This test checks for an open in the SW CKT.
5. This test checks for an open in the instrument cluster.
6. This test checks for an open in the B CKT.
7. This test determines whether the instrument cluster fault is due to an open air bag indicator bulb or an open in the instrument cluster printed circuit.
8. This test checks or a faulty junction block 1.
9. This test determines whether the fault is due to an open in the LA CKT or a faulty center sensor assembly.
10 . This test checks for a short to ground in the instrument cluster circuit.
11. This test checks for a short to ground in the AB CKT.
12. This test determines whether the fault is due to a short to ground in the B CKT or a faulty instrument cluster printed circuit.
13. This test checks for a short to ground in the LA CKT.
14. This test checks for a faulty junction block 1.
15. This test checks for a faulty center sensor assembly.