Reading and Clearing Diagnostic Trouble Codes
How to Troubleshoot the SRS
DTC (Diagnostic Trouble Codes)
The self-diagnostic function of the SRS unit 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 data link circuit.
- When you turn the ignition switch to ON (II), the SRS indicator should come on. If it goes off after 6 seconds, the system is normal, and is not currently detecting any problems.
- If there is a problem, the system locates and defines the problem, stores this information in memory, and turns on the SRS indicator. 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).
- DTCs are either latching or resetting depending on the malfunction. With resetting DTCs, the SRS indicator goes off the next time the ignition switch is turned to ON (II) and the system is normal, but the DTC is still stored. With latching DTCs, the SRS indicator does not turn OFF until the malfunction is repaired and the DTC is cleared.
- When you connect the HDS to the data link connector (DLC), you can retrieve a more detailed DTC in the HDS "SRS" menu.
NOTE: Only read DTCs from the SRS menu, not from SWS menus unless instructed to check SWS DTCs. SWS (ODS unit) DTCs are subcodes of SRS unit DTCs. Only troubleshoot the corresponding SRS DTCs. Also these SWS DTCs are cleared by turning the ignition switch to LOCK (0).
- After reading and recording the DTC, go to the troubleshooting procedure for that code.
Precautions
- Make sure the battery is fully charged. If the battery is dead or low, electrical measurements values may not be correct.
- 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 in 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 SRS wire harness, disconnect the driver's airbag inflator connector, the front passenger's airbag inflator connector, both side airbag inflator connectors, both side curtain airbag inflator connectors, both seat belt tensioner connectors, and both seat belt buckle tensioner connectors.
- 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. Back probe spring-loaded lock type connectors correctly.
How to Read 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, inspect the power line of SRS unit, fuses, and ground, and if there is not any abnormality found, then go to the DLC circuit troubleshooting Testing and Inspection.
5. Use the HDS to check for DTCs.
6. Read and record the DTC.
NOTE:
- Only read DTCs from the SRS menu, not from SWS menus unless instructed to check SWS DTCs. SWS (ODS unit) DTCs are subcodes of SRS unit DTCs. Only troubleshoot the corresponding SRS DTCs. Also these SWS DTCs are cleared by turning the ignition switch to LOCK (0).
- Do not clear the DTC until instructed by the troubleshooting procedure.
7. Turn the ignition switch to LOCK (0), then wait for 10 seconds.
8. Disconnect the HDS from the DLC.
9. Do the troubleshooting procedure for the DTC.
How to Clear DTCs in the HDS
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, go to the DLC circuit troubleshooting 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.
How to Clear DTCs Using the MES Connector Without the HDS
Special Tools Required
- SCS Service Connector 07PAZ-001010A
NOTE: Make sure the battery is fully charged before you begin.
To clear the DTCs from the SRS unit, use the HDS or the following procedure.
1. Make sure the ignition switch is in LOCK (0).
2. Connect the SCS service connector (A) to the yellow MES 2P connector (B). Do not use a jumper wire.
3. Turn the ignition switch to ON (II).
4. The SRS indicator will come on for about 6 seconds, and then go off. Remove the SCS service connector from the MES connector (2P) within 4 seconds after the indicator goes off.
5. The SRS indicator will come on again. Reconnect the SCS service connector to the MES connector (2P) within 4 seconds after the indicator comes on.
6. When the SRS indicator goes off, remove the SCS service connector from the MES connector (2P) within 4 seconds.
7. The SRS indicator blinks two times, indicating that the memory has been cleared.
8. Turn the ignition switch to LOCK (0), then wait for 10 seconds.
9. Turn the ignition switch to ON (II) again. If the SRS indicator comes on for 6 seconds, and then goes off, the system is OK.
Troubleshooting Intermittent Failures
If there was a malfunction that sets a DTC, but it does not recur, a DTC will be stored in the memory, and the SRS indicator may come 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 or damaged cable reel can cause intermittent problem related to the driver's airbag inflator DTCs.
After checking the DTC, troubleshoot as follows:
1. Check for DTCs with the HDS (see How to Read 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, and look for loose connections, poor pin fits, and poor grounds.
6. Take a test-drive (quick acceleration, quick braking, and cornering), turn the steering wheel fully left and right, and hold it there for 5 to 10 seconds. If the problem recurs, the SRS indicator will come on.
7. If you cannot duplicate the concern, ask the client about the conditions when it occurred, or ask the client to demonstrate the concern.
8. If you cannot duplicate the intermittent failure, the system is OK at this time.