Inspection Procedure O-7

Column Switch: ETACS-ECU does not Receive Any Signal from the Taillight Switch, the Headlight Switch, the Passing Light Switch, the Dimmer Switch, the Turn-signal Light Switch or Switch.

Turn-signal Light And Lighting Switch Input Circuit:

NOTE: This troubleshooting procedure requires the use of scan tool MB991958 and SWS monitor kit MB991813. For details on how to use the SWS monitor, refer to "How to use SWS monitor." How To Use SWS Monitor

CIRCUIT OPERATION
The ETACS-ECU operates the following equipment or functions according to signal from the column switch (turn-signal light and lighting switch):
- Light reminder tone alarm function
- Headlight
- Turn-signal light

TECHNICAL DESCRIPTION (COMMENT)
If the signal is not normal, the equipment or functions, which are described in "CIRCUIT OPERATION", do not work normally. If the signal is not normal, the column switch (turn-signal light and lighting switch) or the ETACS-ECU may be defective.

TROUBLESHOOTING HINTS
- The column switch (turn-signal light and lighting switch) may be defective
- The ETACS-ECU may be defective
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector

DIAGNOSIS

Required Special Tools:
- MB991223: Harness Set
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: Vehicles communication interface (V.C.I.)
- MB991827: MUT-III USB cable
- MB991911: MUT-III Main harness B
- MB991813: SWS monitor kit
- MB991806: SWS monitor cartridge
- MB991812: SWS monitor harness (for column-ECU)
- MB991922: Probe harness

STEP 1. Use scan tool MB991958 to select "ECU COMM CHK" on the SWS monitor display.
Check the column-ECU.

CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958. Connect special tool MB991910 before connecting special tool MB991812. Be sure to connect special tool MB991806 after turning on special tool MB991824.







1. Connect the special tool. Refer to "How to connect SWS monitor." How to Connect SWS Monitor
2. Turn the ignition switch to the "ON" position.
3. Operate the scan tool according to the procedure below to display "ECU COMM Check."
a. Select "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "ECU COMM Check."

4. Scan tool (MUT-III) should show "OK" on the "ECU COMM Check" menu for the "COLUMN ECU" menu.

Q: Is "OK" displayed on the "COLUMN ECU" menu?

YES: Go to Step 2.

NO: Refer to Inspection Procedure A-2 "Communication with column switch (column-ECU) is not possible."







STEP 2. Check the turn-signal light and lighting switch.
Remove the turn-signal light and the lighting switch.Then check continuity between the switch terminals.

Q: Is the turn-signal light and lighting switch in good condition?

YES: Go to Step 3.

NO: Replace it. The input signal from the column switch (turn-signal light and lighting switch) should be able to be checked and the functions, which are described in the "Technical Description (comment)," should work normally.

STEP 3. Replacement of ECU

1. Replace the column switch.
2. The input signal from the column switch (turn-signal light and lighting switch) should be able to be checked and the functions, which are described in the "Technical Description (comment)," should work normally.

Q: Is the input signal from the column switch (turn-signal light and lighting switch) input normally?

YES: No action is necessary and testing is complete.

NO: Replace the ETACS-ECU. The input signal from the column switch (turn-signal light and lighting switch) should be able to be checked and the functions, which are described in the "Technical Description (comment)," should work normally.