DTC 25

DTC 25: Passenger's (Front) Air Bag Module (Squib) System Fault 2 (Open in the Squib Circuit)

Passenger's (Front)Air Bag Module (Squib) Circuit:

CIRCUIT OPERATION
- The SRS-ECU judges how severe a collision is by detecting signals from the front air bag analog G-sensor. If the impact is over a predetermined level, the SRS-ECU outputs an ignition signal. At this time, if the front air bag 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
This DTC is set if there is abnormal resistance between the input terminals of the Passenger's (front) air bag module (squib). However, if no DTC reset, the SRS warning light will be switched off (DTC will be retained).

TROUBLESHOOTING HINTS
- Open circuit in the Passenger's (front) air bag module (squib) circuit
- Improper connector contact
- Malfunction of the SRS-ECU

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991911: M.U.T.-III Main Harness B
- MB991865: Dummy resister
- MB991866: Resister harness

STEP 1. Check the Passenger's (front) air bag module (Using scan tool MB991958, read the diagnostic trouble code).

1. Disconnect the negative battery terminal.




2. Disconnect Passenger's (front) air bag module connector C-106.




3. Connect special tool MB991865 to special tool MB991866.

CAUTION: Do not insert a test probe into the terminal from its front side directly, as the connector contact pressure may be weakened.

4. Disconnect the Passenger's (front) air bag module connector C-106, and insert special tool MB991866 into the harness connector by backprobing.
5. Connect the negative battery terminal.
6. Erase the diagnostic trouble code memory, and check the diagnostic trouble code.

Q: Is DTC 25 set?

YES: Go to Step 2.

NO: Replace the Passenger's (front) air bag module. Then go to Step 3.

STEP 2. Check the harness for open circuit between SRS-ECU connector C-12 (terminal No.9 and 10) and the Passenger's (front) air bag module connector C-106 (terminal No.1 and 2).




1. Disconnect Passenger's (front) air bag module connector C-106.




2. Disconnect SRS-ECU connector C-12 and Passenger's (front) air bag module connector C-106.

CAUTION: Do not insert a test probe into the terminal from its front side directly, as the connector contact pressure may be weakened.




3. Check for continuity between the following terminals. It should be less than 2 ohms.
- SRS-ECU connector C-12 (terminal No.9) and the Passenger's (front) air bag module connector C-106 (terminal No.2)
- SRS-ECU connector C-12 (terminal No. 10) and the Passenger's (front) air bag module connector C-106 (terminal No.1)

Q: Does continuity exist?

YES: Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC 25 set, replace the SRS-ECU. Then go to Step 3.

NO: Repair the harness wires between SRS-ECU connector C-12 and Passenger's (front) air bag module connector C-106. Then go to Step 3.

STEP 3. Recheck the diagnostic trouble code.
Check again if the DTC is set.




1. Erase the DTC.
2. Turn the ignition switch to the "ON" position.
3. Check if the DTC is set.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is DTC 25 set?

YES: Return to Step 1.

NO: The procedure is complete (If no malfunctions are found in all steps, an intermittent malfunction is suspected. Refer to How to Use Troubleshooting/INSPECTION Service Points - How to Cope with Intermittent Malfunction).