DTC 76

DTC 76: Right Hand Side-Airbag Module (Squib) System Fault Ground Circuit (Short-Circuit to Ground)

Side-Airbag Module (RH) (Squib) Circuit:

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

DTC SET CONDITIONS
- These DTC is set if there is abnormal resistance between the input terminals of the side-airbag module (RH) (squib).

TROUBLESHOOTING HINTS
- Damaged wiring harnesses or connectors
- Short to ground in the side-airbag module (RH) (squib) harness
- Malfunction of the SRS-ECU

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: Vehicle Communication Interface
- MB991827: MUT-III USB Cable
- MB991911: MUT-III Main Harness B
- MB991865: Dummy resister
- MB991866: Resister harness

STEP 1. Check the side-airbag module (RH) (Using scan tool MB991958, read the diagnostic trouble code).




1. Disconnect the negative battery terminal.
2. 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.

3. Disconnect the side-airbag module (RH) connector D-19, and insert special tool MB991866 into the harness side connector by backprobing.
4. Connect the negative battery terminal.
5. Erase the DTC memory, and then recheck the DTC.

Q: Is DTC 76 output?

YES: Go to Step 2.

NO: Replace the seat back assembly of the front seat (RH). Refer to Front Seat. Then go to Step 4.

STEP 2. Check the harness for short circuit to ground between SRS-ECU and the side-airbag module (RH).




1. Disconnect SRS-ECU connector C-74.




2. Disconnect side-airbag module (RH) connector D-19.
3. Measure at the wiring harness side.

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




4. Check for continuity between terminals 23, 24 and body ground.
- There should be open circuit.

Q: Does continuity exist?

YES: Go to Step 3.

NO: Erase the DTC memory, and recheck if any DTC sets. If DTC 76 sets, replace the SRS-ECU. Then go to Step 4.







STEP 3. Check the harness wires for short circuit to ground between SRS-ECU connector C-74 (terminal No.23 and 24) and side-airbag module (RH) connector D-19 (terminal No.1 and 2).

Q: Are the harness wires between SRS-ECU connector C-74 (terminal No.23 and 24) and side-airbag module (RH) connector D-19 (terminal No.1 and 2) in good condition?

YES: Go to Step 4.

NO: Repair the harness wires between SRS-ECU connector C-74 and side-airbag module (RH) connector D-19. Then go to Step 4.

STEP 4. Recheck for diagnostic trouble code.

Q: Is DTC 76 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).