Inspection Procedure 7: When the TLC Switch Is Pushed on, TLC System Is Not Cancelled

INSPECTION PROCEDURE 7: When the TCL Switch is Pushed On, TCL System is not Cancelled.

TCL Switch System Circuit:

Connector: A-03, C-24, C-126:

CIRCUIT OPERATION
ABS/TCL-ECU terminal 38 is grounded every time the TCL switch is pressed. ABS/TCL-ECU monitors this operation state and turns the TCL ON or OFF.

COMMENT
The cause is probably an open-circuit in the TCL switch circuit.

TROUBLESHOOTING HINTS
^ Malfunction of the TCL switch
^ Damaged harness, connector
^ Malfunction of the ABS/TCL-ECU

DIAGNOSIS

Required Special Tools:
^ MB991223: Harness Set
^ MB991997: ASC Check Harness

STEP 1. Measure the terminal voltage at ABS/TCL-ECU connector A-03.





(1) Connect special tool MB991997 between the ABS/TCL-ECU and the body-side harness connector A-03.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the terminal voltage between special tool MB991997 connector terminal 38 (ABS/TCL-ECU connector A-03 terminal 38) and ground.
^ When the TCL switch is not pressed, the voltage should measure battery positive voltage (approximately 12 volts).
^ When the TCL switch is pressed, the voltage should measure 1 volt or less.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the terminal voltage battery positive voltage when the TCL switch is not pressed, and is the terminal voltage 1 volt or less when the TCL switch is pressed?
YES: Go to Step 6.
NO: Go to Step 2.

STEP 2. Check the TCL switch.





(1) Remove the TCL switch. Refer to Wheel Speed Sensor Removal and Installation.
(2) Connect an ohmmeter to the TCL switch between terminals 1 and 2.
(3) Check for continuity between terminals 1 and 2 when the TCL switch is operated.
^ There is no continuity between terminals 1 and 2 when the TCL switch is not pressed.
^ There is continuity between terminals 1 and 2 when the TCL switch is pressed.

Q: Is there no continuity between terminals 1 and 2 when the TCL switch is not pressed, and is there continuity when the TCL switch is pressed?
YES: Install the TCL switch. Then go to Step 6.
NO: Replace the TCL switch. Then go to Step 7.

STEP 3. Check ABS/TCL-ECU connector A-03, intermediate connector C-24 and TCL switch connector C-126 for loose, corroded or damaged terminals, or terminals pushed back in the connector.








Q: Are there connectors and terminals in good condition?
YES: Go to Step 4.
NO: Repair or replace the faulty connector. Refer to Harness Connector Inspection. Then go to Step 7.

STEP 4. Check the harness wire between ABS/TCL-ECU connector A-03 terminal 38 and TCL switch connector C-126 terminal 1 for damage.








Q: Are there harness wires in good condition?
YES: Go to Step 5.
NO: Repair the damaged harness wire. Then go to Step 7.

STEP 5. Check the harness wire between TCL switch connector C-126 terminal 2 and ground for damage.





Q: Is the harness wire in good condition?
YES: Go to Step 6.
NO: Repair the damaged harness wire. Then go to Step 7.

STEP 6. Retest the system
Q: Is TCL cancelled when the TCL switch is pushed on?
YES: It can be assumed that this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction.
NO: Replace the hydraulic unit (integrated with ABS/TCL-ECU). Then go to Step 7.

STEP 7. Retest the system
Q: Is TCL cancelled when the TCL switch is pushed on?
YES: The procedure is complete.
NO: Return to Step 1.