DTC 91

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

Side Impact Sensor (LH) Power Supply Circuit Part 1:

Side Impact Sensor (LH) Power Supply Circuit Part 2:

CIRCUIT 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-airbags should be deployed, it sends a fire signal to the SRS-ECU to deploy the side-airbags. 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 diagnostic trouble code.

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

TROUBLESHOOTING HINTS
- Damaged wiring harness or connectors
- Malfunction of the side air bag module (LH) (squib)
- 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)
- MB991223 (MB991222): Harness set (Probe)

STEP 1. Check the side impact sensor (LH) power supply circuit at the side impact sensor (LH) connector D-17.




1. Disconnect the negative battery terminal.
2. Disconnect side impact sensor (LH) connector D-17, and measure at the wiring harness side.
3. Connect the negative battery terminal.
4. 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.




5. Measure the voltage between D-17 harness connector terminal 2 and the ground. Voltage should measure 9 volts or more.

Q: Is the measured voltage within the specified range?

YES: Replace the side impact sensor (LH). 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-13 (terminal No.34 and 36) and side impact sensor (LH) connector D-17 (terminal No.1 and 2).

NOTE: After inspecting intermediate connector C-128 inspect the wiring harness. If the intermediate connector C-128 is damaged, repair or replace it. Refer to Harness Connector Inspection. Then go to Step 3.

Q: Are the harness wires between SRS-ECU connector C-13 (terminal No.34 and 36) and side impact sensor (LH) connector D-17 (terminal No.1 and 2) in good condition?

YES: Erase the diagnostic trouble code memory, and check the diagnostic trouble code. If DTC 91 sets, replace the SRS-ECU. Then go to Step 3.

NO: Repair the harness wires between SRS-ECU connector C-13 and side impact sensor (LH) connector D-17. Then go to Step 3.

STEP 3. Recheck for diagnostic trouble code.

Q: Is DTC 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 How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction).