Inspection Procedure 6
INSPECTION PROCEDURE 6: The Neutral Position Learning of the Steering Angular Velocity Sensor is not Detected.
CIRCUIT OPERATION
The ABS system detects the neutral position learning of the steering angular velocity sensor by the signal from the stoplight.
TECHNICAL DESCRIPTION (COMMENT)
The diagnosis is difficult because it depends on driving condition and road surface, if the diagnostic trouble code has not been set, carry out the following checks (refer to TROUBLESHOOTING HINTS).
TROUBLESHOOTING HINTS
The most likely causes for this case are:
^ Damaged wiring harness or connector
^ Malfunction of the stoplight switch system
^ Tires are not all the same diameter
^ Malfunction of suspension
^ Malfunction of the steering angular velocity sensor installation
^ Malfunction of the brake modulator hydraulic unit (integrated with ABS-ECU)
DIAGNOSIS
Required Special Tools:
^ MB991223: Harness Set
^ 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
STEP 1. Check the front tires.
Q: Are the tire diameters different?
YES: Replace the appropriate tire and then go to Step 13.
NO: Go to Step 2.
STEP 2. Check the front suspension.
Q: Is the front suspension abnormal?
YES: Repair the front suspension and then go to Step 13.
NO: Go to Step 3.
STEP 3. Using scan tool MB991958, check data list.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the LOOK (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958 as shown in the illustration.
2. Start the engine.
3. Set scan tool MB991958 to data reading mode for following item.
^ Item 37: Steering angular sensor neutral position learning
4. Confirm the indicated ON/OFF state as follows:
Q: Is the steering angular velocity sensor straight ahead position learning input normal?
YES: Go to Step 5.
NO: Confirm the steering angular velocity sensor is correctly installed. Then go to Step 4.
STEP 4. Check for steering angular velocity sensor output voltage.
1. Connect steering angular velocity sensor connector C-230.
2. Turn the ignition switch to the ON position.
3. Measure the voltage, by backprobing, between terminal 1 and ground, terminal 4 and ground, and terminal 5 and ground. The voltage should measure as indicated in the figure.
Q: Is the steering angular velocity sensor output voltage normal?
YES: Go to Step 13.
NO: Replace the steering angular velocity sensor and then go to Step 13.
STEP 5. Check the stoplight.
Q: Does the stoplight turn on and off normally?
YES: Go to Step 9.
NO: Go to Step 6.
STEP 6. Check the stoplight switch installation condition.
Q: Is the stoplight switch installed correctly?
YES: Check the stoplight switch. Then go to Step 7.
NO: Repair the installation of the stoplight switch. Then go to Step 13.
STEP 7. Check the following connectors.
^ Intermediate connectors C-129
^ Stoplight switch connector C-102
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: Go to Step 8.
NO: Repair it and then go to Step 13.
STEP 8. Check the following harness wires.
^ The wire between relay box in engine compartment (fuse No.10) and stoplight switch connector C-102 (terminal 2)
^ The wire between stoplight switch connector C-102 (terminal 1) and stoplights
Q: Is any harness wire damaged?
YES: Repair or replace it and then go to Step 13.
NO: Go to Step 9.
STEP 9. Check the stoplight switch circuit. Measure the voltage at ABS-ECU connector B-118.
1. Disconnect ABS-ECU connector B-118 and measure at the harness side.
2. Depress the brake pedal to turn on the stoplight switch.
3. Measure the voltage between terminal 19 and ground. It should measure battery voltage (approximately 12 volts).
Q: Is battery positive voltage (approximately 12 volts) present?
YES: Go to Step 12.
NO: Go to Step 10.
STEP 10. Check the following connectors.
^ ABS-ECU connector B-118
^ Joint connector C-105
^ Intermediate connector C-124
^ Stoplight switch connector C-102 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: Go to Step 11.
NO: Repair it and then go to Step 13.
STEP 11. Check the following harness wire.
The wire between stoplight switch connector C-102 (terminal 1) and ABS-ECU connector B-118 (terminal 19)
Q: Is the harness wire damaged?
YES: Repair or replace it and then go to Step 13.
NO: Go to Step 13.
STEP 12. Check the following connector.
ABS-ECU connector B-118
Check the connector for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Are the connector and terminals in good condition?
YES: Replace the brake modulator hydraulic unit (integrated with ABS-ECU). Then go to Step 13.
NO: Repair it and then go to Step 13.
STEP 13. Retest the system.
Q: Is the neutral position learning of the steering angular velocity sensor detected by the ABS system?
YES: The procedure is complete.
NO: Return to Step 1.