Sir Diagnostic System Check: Description

WARNING: This page is about a different car, the 1991 Geo Storm, 1991 Geo Metro, 1990 Geo Storm, and 1990 Geo Metro. However, it is still accessible from the selected car via links, so may be relevant.

Diagnostic procedures used in this section are designed to find and repair SIR problems. For best results, utilize diagnostic charts and follow sequence listed below.

Perform SIR DIAGNOSTIC SYSTEM CHECK. SIR DIAGNOSTIC SYSTEM CHECK should be starting point of any SIR diagnostics. SIR DIAGNOSTIC SYSTEM CHECK checks for proper INFLATABLE RESTRAINT indicator light operation and for SIR trouble codes.
Refer to proper diagnostic charts as directed by SIR DIAGNOSTIC SYSTEM CHECK. SIR DIAGNOSTIC SYSTEM CHECK will lead to correct chart to diagnose any SIR problem. By-passing these procedures may result in extended diagnostic time.
Repeat SIR DIAGNOSTIC SYSTEM CHECK after performing any repair or diagnostic procedures. Performing SIR DIAGNOSTIC SYSTEM CHECK after all repair or diagnostic procedures will ensure repair has been made correctly and no other conditions exist.

When ignition switch is first turned on, system voltage is applied through SIR fuse No. 2 (C-23) to DERM at IGNITION 1 input and through SIR fuse No. 1 (C-22) to DERM at SIR INDICATOR LOW and SIR INDICATOR HIGH inputs. DERM responds by flashing INFLATABLE RESTRAINT indicator light 7 times.

When engine is cranked, system voltage is applied to DERM at CRANK input. DERM grounds lamp circuit until system voltage is removed from CRANK input.

This results in a steady INFLATABLE RESTRAINT indicator light during cranking.

After engine is cranked, DERM will again flash INFLATABLE RESTRAINT indicator light 7 times.

NOTE: Test numbers refer to test numbers on diagnostic chart. For circuit number identification, see WIRING DIAGRAMS .

INFLATABLE RESTRAINT indicator light should flash 7 times as ignition is just turned on. If indicator does not respond, use CHART C or D to diagnose indicator malfunction.
As engine is cranked, INFLATABLE RESTRAINT indicator light should remain on steadily. If indicator does not respond, use CHART E to diagnose malfunction.
INFLATABLE RESTRAINT indicator light has completed BULB CHECK and remains on, indicating a current code has been detected. At this point, a Scan tool or INFLATABLE RESTRAINT indicator light can be used to diagnose malfunction. For FLASH CODE DIAGNOSIS, use CHART B.
After cranking engine, INFLATABLE RESTRAINT indicator light should flash 7-9 times and then go out. If indicator begins to flash a Code 12, there is a system fault. Use CHART F to diagnose malfunction.
INFLATABLE RESTRAINT indicator light has completed BULB CHECK and is indicating no current codes exist.
Record all codes (both history and current) onto repair order. If there are no codes (history or current), record this fact onto repair order. No further diagnosis is required. If Scan tool indicates no data is being received from DERM, data link will require repair.
If multiple codes are displayed (history or current), order in which codes are diagnosed is very important. Refer to recommended charts.

Fig 1: SIR Diagnostic System Check

Courtesy of GENERAL MOTORS CORP.