DTC 21

DTC 21 - Driver's Side Air Bag Module (Squib) System

DTC 21, 22, 61, 62 - Driver's Side Air Bag Module (squib) Circuit:

Connector - C-72, C-81, C-85:

CIRCUIT OPERATION
The SRS-ECU judges how severe a collision is by detecting signals from the left and right side impact sensors and the analog G-sensor. If the impact is over a predetermined level, the SRS-ECU outputs an ignition signal. At this time, if the safing G-sensor is on, the SRS air bag will inflate.

The ignition signal is input to the air bag module via the clock spring to inflate the air bag.




DTC SET CONDITIONS
These diagnostic trouble codes are output if there is abnormal resistance between the input terminals of the driver's side air bag module (squib). The most likely causes for this code to be set are shown in the table.

However, if no diagnostic trouble code resets, the SRS warning light will be switched off (The diagnostic trouble code will be retained).

TROUBLESHOOTING HINTS
- Malfunction of the clock spring
- Damaged wiring harnesses or connectors
- Malfunction of the driver's side air bag module (squib)
- Malfunction of the SRS-ECU

DIAGNOSIS

Required Special Tools:
MB991502: Scan Tool (MUT-II)
MB991613: SRS Check Harness

STEP 1. Check the driver's side air bag module line using the scan tool and MB991613 SRS Check harness.
1. Remove the driver's side air bag module.
2. Connect connector (4) of special tool MB991613 to clock spring connector C-63.
3. Connect connector (1) of special tool MB991613 to connector (2).
4. Connect terminals 22 to 24, and terminals 23 to 25 of special tool MB991613 connector (5).
5. Connect the clock spring to the body wiring harness.
6. Connect the negative battery terminal.
7. Erase the diagnostic trouble code memory. Is code number 21, 22, 61 or 62 output?

If yes, go to Step 2.
If no output, replace the driver's side air bag module. Then go to Step 4.

STEP 2. Check the clock spring.
Then go to Step 4.
If the clock spring is normal, go to step 3.

STEP 3. Check the harness wires between SRS-ECU connector C-72 and clock spring connector C-85.
If harness wires are in good condition, go to Step 4. If any harness wires between SRS-ECU connector C-72 and clock spring connector C-85 are damaged, repair them. Then go to Step 4.

Connector - C-85:

STEP 4. Check the diagnostic trouble codes.
Confirm that diagnostic trouble code 21, 22, 61 and 62 are not output.