Inspection Procedure 7: When the TCL Switch Is Pushed On, TCL System Is Not Canceled

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

TCL Switch System Circuit:

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.
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. 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 canceled when the TCL switch is pushed on?
YES: It can be assumed that this malfunction is intermittent.
NO: Replace the hydraulic unit (integrated with ABS/TCL-ECU). Then go to Step 7.

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