DTC 91

DTC 91: Left Hand Side-Impact Sensor 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 SRS-ECU judges how severe a collision is by detecting signals from the side impact sensor. 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.

DTC SET CONDITIONS
- This DTC will set when the power supply voltage to the left-side impact sensor 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-airbag module (LH) (squib)
- 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
- MB991223 (MB991222): Harness set (Probe)

STEP 1. Check the side impact sensor (LH) line at the SRS-ECU connector C-74.




1. Disconnect the negative battery terminal.
2. Disconnect side impact sensor (LH) connector D-12, 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 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-74 (terminal No.34 and 36) and side impact sensor (LH) connector D-12 (terminal No.1 and 2).

Q: Are the harness wires between SRS-ECU connector C-74 (terminal No.34 and 36) and side impact sensor (LH) connector D-12 (terminal No.1 and 2) in good condition?

YES: Erase the DTC memory, and recheck if any DTC sets. If DTC 91 steps. Replace the SRS-ECU.

NO: Repair the harness wires between SRS-ECU connector C-74 and side impact sensor (LH) connector D-12. 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).