Diagnosis code 91: Side Impact Sensor (LH) Power Supply Circuit System

OPERATION

The side impact sensor includes an analog G sensor and CPU, etc. The CPU monitors the analog G sensor output signal. If the CPU judges that the side air bags should be deployed, it sends a fire signal to the SRS-ECU to deploy the side air bags. Besides that, the CPU diagnoses the internal components of the side impact sensor. If a malfunction occurs, it requests the SRS-ECU to set a diagnosis code.

DIAGNOSIS CODE SET CONDITIONS

This diagnosis code will set when the power supply voltage to the side impact sensor (LH) remains less than a predetermined value for 5 seconds. However, if the system returns to normal condition, code number 91 will be erased automatically and the SRS warning lamp will go out.

PROBABLE CAUSES

Damaged wiring harness or connectors

Malfunction of the side air bag module (LH) (squib)

Malfunction of the SRS-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check the side impact sensor (LH) power supply circuit at the side impact sensor (LH) connector D-27.

Disconnect the negative battery terminal.

Disconnect side impact sensor (LH) connector D-27, and measure at the wiring harness side.

Connect the negative battery terminal.

Turn the ignition switch to the "ON" position.

CAUTION

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

Measure the voltage between D-27 harness side connector terminal 2 and the earth.

OK: 9 V or more

Q: Is the check result normal?

YES: Replace the side impact sensor (LH) (Refer to

). Then go to Step 3

.
NO: Go to Step 2

STEP 2. Check the harness wires for open circuit or short circuit between SRS-ECU connector C-114 (terminal No.34 and 36) and side impact sensor (LH) connector D-27 (terminal No.1 and 2).

NOTE: After inspecting intermediate connector D-50 inspect the wiring harness. If the intermediate connector D-50 is damaged, repair or replace it. Then go to Step 3

Q: Are the harness wires between SRS-ECU connector C-114 (terminal No.34 and 36) and side impact sensor (LH) connector D-27 (terminal No.1 and 2) in good condition?

YES: Erase the diagnosis code memory, and check the diagnosis code. If diagnosis code 91 sets, replace the SRS-ECU (Refer to

). Then go to Step 3

.
NO: Repair the harness wires between SRS-ECU connector C-114 and side impact sensor (LH) connector D-27. Then go to Step 3

STEP 3. Check whether the diagnosis code is reset.

Q: Is diagnosis code 91 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 91: Side Impact Sensor (LH) Power Supply Circuit System

OPERATION The side impact sensor includes an analog G sensor and CPU, etc. The CPU monitors the analog G sensor output signal. If the CPU judges that the side air bags should be deployed, it sends a fire signal to the SRS-ECU to deploy the side air bags. Besides that, the CPU diagnoses the internal components of the side impact sensor. If a malfunction occurs, it requests the SRS-ECU to set a diagnosis code.
DIAGNOSIS CODE SET CONDITIONS This diagnosis code will set when the power supply voltage to the side impact sensor (LH) remains less than a predetermined value for 5 seconds. However, if the system returns to normal condition, code number 91 will be erased automatically and the SRS warning lamp will go out.
PROBABLE CAUSES Damaged wiring harness or connectors Malfunction of the side air bag module (LH) (squib) Malfunction of the SRS-ECU
	DIAGNOSIS PROCEDURE

	STEP 1. Check the side impact sensor (LH) power supply circuit at the side impact sensor (LH) connector D-27. Disconnect the negative battery terminal. Disconnect side impact sensor (LH) connector D-27, and measure at the wiring harness side. Connect the negative battery terminal. Turn the ignition switch to the "ON" position.
	CAUTION Do not insert a test probe into the terminal from its front side directly as the connector contact pressure may be weakened. Measure the voltage between D-27 harness side connector terminal 2 and the earth. OK: 9 V or more Q: Is the check result normal? YES: Replace the side impact sensor (LH) (Refer to ). Then go to Step 3. NO: Go to Step 2.
	STEP 2. Check the harness wires for open circuit or short circuit between SRS-ECU connector C-114 (terminal No.34 and 36) and side impact sensor (LH) connector D-27 (terminal No.1 and 2). NOTE: After inspecting intermediate connector D-50 inspect the wiring harness. If the intermediate connector D-50 is damaged, repair or replace it. Then go to Step 3 . Q: Are the harness wires between SRS-ECU connector C-114 (terminal No.34 and 36) and side impact sensor (LH) connector D-27 (terminal No.1 and 2) in good condition? YES: Erase the diagnosis code memory, and check the diagnosis code. If diagnosis code 91 sets, replace the SRS-ECU (Refer to ). Then go to Step 3 . NO: Repair the harness wires between SRS-ECU connector C-114 and side impact sensor (LH) connector D-27. Then go to Step 3.
	STEP 3. Check whether the diagnosis code is reset. Q: Is diagnosis code 91 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 .