SIR SYSTEMS DIAGNOSIS REVISED FACING PAGES. Geo Storm 1991

For 1990-2009 cars

# SIR SYSTEMS DIAGNOSIS REVISED FACING PAGES

#### Subject: SUPPLEMENTAL INFLATABLE RESTRAINT (SIR) SYSTEM DIAGNOSIS REVISED FACING PAGES

#### Model and Year: 1990-91 STORM WITH 1.6L SOHC AND 1.6L DOHC

THIS BULLETIN CANCELS AND SUPERSEDES DEALER SERVICE BULLETIN NO. 91-219-9, DATED FEBRUARY 1991. THE ENGINE APPLICATIONS HAVE BEEN CHANGED. ALL COPIES OF 91-219-9 SHOULD BE DISCARDED.

This bulletin serves to make updates in the 1990-1991 Geo Storm (VIN 5 and 6) "R" Carline Service Manual, Section 9J-A "SIR System Diagnosis". The following pages should be replaced.

Page 9J-A-28 Facing Page, Code 21 Steering Column Resistance Too High Page 9J-A-29 Diagnosis Chart, Code 21 Steering Column Resistance Too High Page 9J-A-30 Facing Page, Code 22 Steering Column Resistance Too Low Page 9J-A-31 Diagnosis Chart, Code 22 Steering Column Resistance Too Low Page 9J-A-32 Facing Page, Code 21 and Code 22 Both Current Page 9J-A-33 Diagnosis Chart, Code 21 and Code 22 Both Current

#### CODE 21 STEERING COLUMN RESISTANCE TOO HIGH

#### Test Conditions:

Tested once each ignition cycle during the "Steering Column Resistance Test" if: 1) No faults are detected during "Turn-ON"; 2) No faults are detected during "Continuous Monitoring" for 1 second: 3) No Crank signal present.

#### Failure Conditions:

Code 21 will set if the combined resistance of the Inflator Module, SIR Coil, harness wiring and connector terminal contact in the steering column is greater than a specified value.

#### Conditions To Clear:

Current Code 21 will be cleared each time the Ignition Switch is turned "OFF."

#### Action Taken:

DERM turns "ON" the "INFLATABLE RESTRAINT" indicator lamp.

#### Description:

-------------- The DERM injects a current of 75 milliamperes through the steering column from the "Force Hi" output terminal "A4" to the "Force Low" input terminal "A10". By monitoring the voltage at the "Sense Hi" input terminal "A7" and the "Sense Low" input terminal "A6" the DERM calculates the combined resistance of the Inflator Module, SIR Coil, harness wiring (CKTs 347, 348 and 349) and connector terminal contact in the steering column. Code 21 will set if the resistance is greater than 4.37 ohms value or the 100 ohm resistors within the Resistor Module is shorted.

#### Notes on Fault Tree:

1. Checks if fault is in steering column. The SIR Load Tester simulates the resistance of good steering column wiring and components.

2. Determines if fault is in Inflator Module or in the SIR Coil. The SIR Load Tester simulates the resistance of a good Inflator Module.

3. Checks if 430 ohm resistor in the Resistor Module is shorted

4. Checks the Resistor Module for internal shorts.

5. Checks the resistance of circuits between the Resistor Module and the DERM.

6. CHECKS FOR "SENSE HI" SHORTED TO VOLTAGE.

#### CODE 22 STEERING COLUMN RESISTANCE TOO LOW

#### Test Conditions:

Tested once each ignition cycle during the "Steering Column Resistance Test" if: 1) No faults are detected during "Turn ON"; 2) No faults are detected during the "Continuous Monitoring" for 1 second; 3) No "CRANK" signal present.

#### Failure Conditions:

Code 22 will set if the combined resistance of the Inflator Module, SIR oil. harness wiring and connector terminal contact in the steering column is greater than a specified value.

#### Conditions To Clear:

Current Code 22 will be cleared each time the ignition switch is turned "OFF."

#### Action Taken:

DERM turns "ON" the "INFLATABLE RESTRAINT" indicator lamp.

#### Description:

The DERM injects a current of 75 milliamperes through the steering column from the "Force HI" output terminal "A4" to the "Force Low" input terminal "A10". By monitoring the voltage at the "Sense Hi" input-terminal "A7" and the "Sense Low" input terminal "A6" the DERM calculates the combine resistance of the Inflator Module, SIR Coil, harness wiring (CKTs 347, 348 and 349) and connector terminal contact in the steering column. Code 22 will set if: o The steering column resistance is less than a specified value. o The 430 ohm resistor in the Resistor Module is shorted. o The resistance of the 100 ohm resistor in the Resistor Module is too high. o The high side of the deployment loop is shorted to the low side of the deployment loop.

Notes on Fault Tree:

1. Checks if fault is in steering column. the SIR Load Tester J 37808 simulates the resistance of good steering column wiring and components. 2. Determines if fault is in Inflator Module or in the SIR Coil. The SIR Load Tester J 37808 simulates the resistance of a good Inflator Module. Use adapter kit J 37808-50. 3. Determines if fault is on deployment loop side or DERM side of resistor module. 4. Checks for open in "Sense Hi" (CKT 753). 5. CHECKS FOR A SHORTED CKT 688 TO CKT 753.

#### CODE 21 AND 22 BOTH CURRENT STEERING COLUMN RESISTANCE UNDETERMINED

#### Test Conditions:

Tested once each ignition cycle during the "Steering Column Resistance Test" if: 1) No faults are detected during "Turn-ON"; 2) No faults are detected during "Continuous Monitoring" for 1 second; 3) No "CRANK" signal present.

#### Failure Conditions:

Code 21 and 22 will set if the voltage at the "Sense Low" input terminal "A6" is less than 5 volts during the first portion of the steering column resistance test. This will occur when the "Force Hi" output terminal "A4" is open and results in an undetermined steering column resistance.

#### Conditions To Clear:

Current Code 21 and 22 will be cleared each time the Ignition Switch is turned "OFF."

#### Action Taken:

DERM turns "ON" the "INFLATABLE RESTRAINT" indicator lamp.

#### Description:

------------ The DERM injects a current of 75 milliamperes through the steering column from the "Force Hi" output terminal "A4" to the "Force Low" input terminal "A10". By monitoring the voltage at the "Sense Hi" input terminal "A7" and the "Sense Low" input terminal "A6" the DERM calculates the combine resistance of the Inflator Module, SIR Coil, harness wiring and connector terminal contact in the steering column. Code 22 and 21 will set if the "Force Hi" output terminal "A4" is open.

#### Notes on Fault Tree:

1. Checks for opening "Force Hi" wiring. 2. Checks for open 50 ohm resistor in Resistor Module. 3. Checks for proper values in Resistor Module. 4. Checks for short in Resistor Module wiring harness. 5. Checks for short in Resistor Module wiring harness.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.