Diagnosis code 86: Side Air bag Module (LH) (Squib) System Fault Earth Circuit (Short-Circuited to Earth)

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 air bag safing G-sensor is on, the SRS side air bag will inflate.

The ignition signal is input to the side air bag module to inflate the side air bag.

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code is set if there is abnormal resistance between the input terminals of the side air bag module (LH) (squib).

PROBABLE CAUSES

Damaged wiring harnesses or connectors

Short to earth in the left hand side air bag module (squib) harness

Malfunction of the SRS-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check the side air bag module (LH) (Check whether the diagnosis code is reset).

Disconnect the negative battery terminal.

Disconnect the side air bag module (LH) connector D-08.

Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991866).

CAUTION

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

Insert special tool MB991866 into the D-08 harness side connector by backprobing.

Connect the negative battery terminal.

Erase the diagnosis code memory, and check the diagnosis code.

Q: Is diagnosis code 86 set?

YES: Go to Step 2

.
NO: Replace the seat back assembly of the front seat (LH) (Refer to GROUP 52A - Front Seat

). Then go to Step 4

STEP 2. Check the side air bag module (LH) circuit at the SRS-ECU connector C-114.

Disconnect SRS-ECU connector C-114.

Disconnect side air bag module (LH) connector D-08.

CAUTION

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

Check for continuity between C-114 harness side connector terminals 21, 22 and body earth.

OK: Open circuit

Q: Is the check result normal?

YES: Erase the diagnosis code memory, and check the diagnosis code. If diagnosis code 86 sets, replace the SRS-ECU (Refer to

). Then go to Step 4

.
NO: Go to Step 3

STEP 3. Check the harness wires for short circuit to earth between SRS-ECU connector C-114 (terminal No.21 and 22) and side air bag module (LH) connector D-08 (terminal No.1 and 2).

Q: Are the harness wires between SRS-ECU connector C-114 (terminal No.21 and 22) and side air bag module (LH) connector D-08 (terminal No.1 and 2) in good condition?

YES: Go to Step 4

.
NO: Repair the harness wires between SRS-ECU connector C-114 and side air bag module (LH) connector D-08. Then go to Step 4

STEP 4. Check whether the diagnosis code is reset.

Q: Is diagnosis code 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 GROUP 00 - How to Use Troubleshooting/Inspection Service Points


Diagnosis code 86: Side Air bag Module (LH) (Squib) System Fault Earth Circuit (Short-Circuited to Earth)

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 air bag safing G-sensor is on, the SRS side air bag will inflate. The ignition signal is input to the side air bag module to inflate the side air bag.
DIAGNOSIS CODE SET CONDITIONS This diagnosis code is set if there is abnormal resistance between the input terminals of the side air bag module (LH) (squib).
PROBABLE CAUSES Damaged wiring harnesses or connectors Short to earth in the left hand side air bag module (squib) harness Malfunction of the SRS-ECU
	DIAGNOSIS PROCEDURE

	STEP 1. Check the side air bag module (LH) (Check whether the diagnosis code is reset). Disconnect the negative battery terminal. Disconnect the side air bag module (LH) connector D-08.
	Connect special tool dummy resistor (MB991865) to special tool resistor harness (MB991866). CAUTION Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened. Insert special tool MB991866 into the D-08 harness side connector by backprobing. Connect the negative battery terminal. Erase the diagnosis code memory, and check the diagnosis code. Q: Is diagnosis code 86 set? YES: Go to Step 2. NO: Replace the seat back assembly of the front seat (LH) (Refer to GROUP 52A - Front Seat ). Then go to Step 4.
	STEP 2. Check the side air bag module (LH) circuit at the SRS-ECU connector C-114. Disconnect SRS-ECU connector C-114. Disconnect side air bag module (LH) connector D-08.
	CAUTION Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened. Check for continuity between C-114 harness side connector terminals 21, 22 and body earth. OK: Open circuit Q: Is the check result normal? YES: Erase the diagnosis code memory, and check the diagnosis code. If diagnosis code 86 sets, replace the SRS-ECU (Refer to ). Then go to Step 4 . NO: Go to Step 3.
	STEP 3. Check the harness wires for short circuit to earth between SRS-ECU connector C-114 (terminal No.21 and 22) and side air bag module (LH) connector D-08 (terminal No.1 and 2). Q: Are the harness wires between SRS-ECU connector C-114 (terminal No.21 and 22) and side air bag module (LH) connector D-08 (terminal No.1 and 2) in good condition? YES: Go to Step 4 . NO: Repair the harness wires between SRS-ECU connector C-114 and side air bag module (LH) connector D-08. Then go to Step 4.
	STEP 4. Check whether the diagnosis code is reset. Q: Is diagnosis code 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 GROUP 00 - How to Use Troubleshooting/Inspection Service Points .