Reading and Clearing Diagnostic Trouble Codes

How to Troubleshoot the SRS

DTC (Diagnostic Trouble Codes)

The self-diagnostic function of the SRS system allows it to locate the causes of system problems and store this information in memory. For easier troubleshooting, this data can be retrieved with the HDS via the data link circuit.

- When you turn the ignition switch to ON (II), the SRS indicator comes on. If it goes off after 6 seconds, the system is normal with no problems detected.
- If a problem is detected, the system locates and defines the problem, stores this information in memory, and turns on the SRS indicator on. The data remains in memory even if the ignition switch is turned to LOCK (0) or the battery is disconnected.
- The data is stored in memory as a diagnostic trouble code (DTC).
- SRS DTCs are either latching or resetting depending upon the malfunction. Latching DTCs cause the SRS system to light the SRS indicator until the problem is corrected and the DTCs are cleared. Resetting DTCs cause the SRS system to light the SRS indicator until the ignition switch is turned off. If the malfunction does not occur when the ignition switch is subsequently turned to ON (II), the SRS system turns off the SRS indicator, although the DTCs are still stored until cleared.
- When you connect the HDS to the data link connector (DLC), you can retrieve a more detailed DTC in the HDS "SRS" menu.
- After reading and recording the DTC, proceed with the troubleshooting procedure for that code.

Precautions

- Use only a digital multimeter to check the system. Make sure its output is 10 mA (0.01 A) or less when switched to the smallest value in the ohmmeter range. A tester with a higher output could damage the airbag circuit or cause accidental airbag deployment and possible injury.
- Whenever the ignition switch is ON (II), or has been turned to LOCK (0) for less than 3 minutes, be careful not to bump the SRS unit; the airbags could accidentally deploy and cause damage or injuries.
- Before removing the dashboard wire harness or floor wire harness, disconnect the driver's airbag connector, the front passenger's airbag connector, both side airbag connectors, both side curtain airbag connectors, and both seat belt tensioner connectors.
- Make sure the battery is fully charged. If the battery is dead or low, electrical measurements may not be correct.
- Do not touch a tester probe to the terminals in the SRS unit or harness connectors, and do not connect the SRS unit terminals or the sensor terminals with a jumper wire. Use only the back probe set and the multimeter to back probe spring-loaded lock type connectors correctly.

How to Retrieve DTCs

NOTE: Make sure the battery is fully charged before you begin.

1. Make sure the ignition switch is in LOCK (0).

2. Connect the HDS to the data link connector (DLC) (A).

3. Turn the ignition switch to ON (II).

4. Make sure the HDS communicates with the vehicle and the SRS unit. If it does not communicate, troubleshoot the DLC circuit Testing and Inspection.

5. In the SRS MENU of the HDS, select SRS, then DTC to clear DTCs.

6. Turn the ignition switch to LOCK (0), then wait for 10 seconds.

7. Disconnect the HDS from the DLC.

Troubleshooting Intermittent Failures

If there was a malfunction that sets a DTC, but it does not recur, it will be stored in the memory as an intermittent failure, and the SRS indicator may come on depending on the malfunction detected.

NOTE:

- Check the condition of the battery Battery Test, and the charging system Alternator and Regulator Circuit Troubleshooting. Low battery voltage may cause some intermittent failures.
- A faulty cable reel can cause intermittent connections which will produce driver's airbag inflator DTCs.

After checking the DTC, troubleshoot as follows:

1. Check for DTCs with the HDS (see How to Retrieve DTCs).

2. Clear the DTCs with the HDS (see How to Clear DTCs).

3. Set the parking brake, then start the engine, and let it idle.

4. The SRS indicator comes on for about 6 seconds and then goes off.

5. Shake the related wire harnesses and the connectors. Look for loose connections and poor grounds.

6. Take a test-drive (quick acceleration, quick braking, and cornering). Turn the steering wheel fully left and right, and holding it at full lock for 5 to 10 seconds. If the problem recurs, the SRS indicator will come on.

7. If you cannot duplicate the concern, ask the customer about the conditions when it occurred, or ask the customer to demonstrate the concern.

8. If you cannot duplicate the intermittent failure, the system is OK at this time.