Inspection Procedure 4

INSPECTION PROCEDURE 4: Steering wheel sensor power supply circuit system





















CIRCUIT OPERATION

- The steering wheel sensor is energized by the ignition switch (IG1) through multi-purpose fuse No.2 and the steering wheel sensor terminal 2.
- If the power supply to the steering wheel sensor has failed, scan tool (M.U.T.-III Sub Assembly) will not be able to communicate with it.

TROUBLESHOOTING HINTS (THE MOST LIKELY CAUSES FOR THIS CASE:)

- Damaged wiring harness or connector
- Defective battery
- Charging system failed
- Malfunction of the steering wheel sensor

DIAGNOSIS

Required Special Tools:

- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A
- MB991997: ASC Check Harness

STEP 1. Measure the voltage at steering wheel sensor connector C-312.





(1)Disconnect the connector C-312.
(2)Turn the ignition switch to the "ON" position.
(3)Measure the voltage between terminal 2 and ground. It should measure approximately 12 volts (battery positive voltage).

Q. Is battery positive voltage (approximately 12 volts) present?

YES Go to Step 3.

NO Go to Step 2.

STEP 2. Check the following connectors.

















- Joint connectors (2) C-01
- Junction block connectors C-202 and C-215
- Ignition switch connector C-308
- Steering wheel sensor connector C-312
Check the connectors, for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Are the connectors and terminals in good condition?

YES An open or short circuit may be present in the power supply line to the steering wheel sensor. Repair the wiring harness between steering wheel sensor connector C-312 terminal 2 and ignition switch connector C-308 terminal 4. Go to Step 8.

NO Repair or replace the damaged component(s). Harness Connector Inspection. Then go to Step 8.

STEP 3. Measure the resistance at steering wheel sensor connector C-312.





(1)Disconnect the steering sensor connector C-312, and measure at the harness side connector.
(2)Measure the resistance between terminal 5 and body ground.

Q. Is the measured resistance 2 ohms or less?

YES Go to Step 5.

NO Go to Step 4.

STEP 4. Check steering wheel sensor connector C-312 for loose, corroded or damaged terminals, or terminals pushed back in the connector.





Q. Are the connectors and terminals in good condition?

YES An open circuit may be present in the ground circuit. Repair the wiring harness between steering wheel sensor connector C-312 terminals 5 and the body ground. Then go to Step 8
.

NO Repair or replace the damaged component(s). Harness Connector Inspection. Then go to Step 8.

STEP 5. Check the battery.

Check the battery Battery Test).

Q. Is the battery in good condition?

YES Go to Step 6.
NO Charge or replace the battery. Then go to Step 8.
STEP 6. Check the charging system.

Check the charging system Initial Inspection and Diagnostic Overview).

Q. Is the charging system in good condition?

YES Go to Step 7.
NO Repair or replace the charging system component(s).Then go to Step 8.
STEP 7. Retest the system.

Q. Can the steering wheel sensor communicate with the scan tool (M.U.T.-III Sub Assembly)?

YES It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.
NO Replace the steering wheel sensor. Then go to Step 8.
STEP 8. Retest the system.

Q. Can the steering wheel sensor communicate with the scan tool (M.U.T.-III Sub Assembly)?

YES The procedure is complete.
NO Go to Step 1.