DTC 86

DTC 86: Side-Airbag Module (LH) (Squib) System Fault Ground Circuit (Short-Circuited to Ground)

Side-Airbag Module (LH) (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 side-airbag will inflate.
- The ignition signal is input to the side-airbag module to inflate the side-airbag.

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

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

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: MUT-III USB Cable
- MB991911: MUT-III Main Harness B (Vehicles without CAN communication system)
- MB991865: Dummy resister
- MB991866: Resister harness

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

1. Disconnect the negative battery terminal.




2. Disconnect the side-airbag module (LH) connector D-19.




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. Insert special tool MB991866 into the D-19 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 86 set?

YES: Go to Step 2.

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

STEP 2. Check the side-airbag module (LH) circuit at the SRS-ECU connector C-13.




1. Disconnect SRS-ECU connector C-13.




2. Disconnect side-airbag module (LH) connector D-19.




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 C-13 harness connector terminals 21, 22 and body ground.
It should be open circuit.

Q: Does continuity exist?

YES: Go to Step 3.

NO: Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC 86 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-13 (terminal No.21 and 22) and side-airbag module (LH) connector D-19 (terminal No.1 and 2).

Q: Are the harness wires between SRS-ECU connector C-13 (terminal No.21 and 22) and side-airbag module (LH) 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-13 and side-airbag module (LH) connector D-19. Then go to Step 4.

STEP 4. Recheck for diagnostic trouble code.

Q: Is DTC 86 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)