GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2002 🢒 Eldorado 🢒 Body and Accessories 🢒 Wiring Systems 🢒 Diagnostic System Check - SIR

Caution: In order to avoid deploying the air bag when troubleshooting the SIR system, use only the equipment specified in this manual and the instructions given in this manual. Failure to use the specified equipment as instructed could cause air bag deployment, personal injury to you or someone else, or unnecessary SIR system repairs.

Caution: If any water enters the vehicle's interior up to the level of the carpet or higher and soaks the carpet, the sensing and diagnostic module (SDM) and the SDM harness connector may need to be replaced. The SDM could be activated when powered, which could cause deployment of the air bag(s) and result in personal injury. Before attempting these procedures, the SIR system must be disabled. Refer to Disabling the SIR System.

With the ignition OFF, inspect the SDM mounting area, including the carpet. If any significant soaking or evidence of significant soaking is detected, you must perform the following tasks:

  1. Remove all water.
  2. Repair the water damage.
  3. Replace the SDM harness connector.
  4. Replace the SDM.
Failure to follow these tasks could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs.

These diagnostic procedures will help you to find and repair SIR system malfunctions. For best results, use the diagnostic tables, and follow the sequence listed below:

  1. Refer to the diagnostic table as directed by the diagnostic system check-SIR. Bypassing these procedures may result in the following:
    2. • Extended Diagnostic Time
    • Incorrect Diagnosis
    • Incorrect Parts Replacement
  2. Repeat the SIR diagnostic system check after you perform any repair or diagnostic procedures. This will verify that you correctly performed the repair. This will also ensure that no other malfunctions exist.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. Test to see if AIR BAG warning indicator flashes seven times when the ignition is first turned ON.

    2.

  2. Test to see if scan tool powers up.

    3.

  3. Test to see if the scan tool can communicate with the inflatable restraint sensing and diagnostic module (SDM).

    4.

  4. Test to see if there are any current or history diagnostic trouble codes (DTCs) present.

    5.

  5. Test to see if there are any communication DTCs (U-codes) present.

Step

Action

Yes

No

1

Note the AIR BAG warning indicator while turning ON the ignition, with the engine OFF.

Does the AIR BAG warning indicator flash seven times?

Go to Step 2

Go to Symptoms - SIR

2

Install a scan tool.

Does the scan tool power up?

Go to Step 3

Go to Scan Tool Does Not Power Up in Data Link Communications

3

Attempt to establish communication with the inflatable restraint sensing and diagnostic module (SDM).

Does the scan tool communicate with the SDM?

Go to Step 4

Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

4

  1. Use the scan tool to request the SIR diagnostic trouble code (DTC) display.
  2. Record the displayed DTCs on the repair order, specifing as current or history.

Does the scan tool display any current and/or history DTCs?

Go to Step 5

System OK

5

Does the scan tool display any DTCs which begin with a "U"?

Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications

Go to Step 6

6

Does the scan tool display DTC B1327 or B1328?

Go to Diagnostic Trouble Code (DTC) List in Engine Electrical

Go to Diagnostic Trouble Code (DTC) List