Inspection Procedure N-6

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.

Turn-Signal Lighting And 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 (lighting and turn-signal light 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: Vehicle Communication Interface (V.C.I.)
- MB991827: MUT-III USB Cable
- MB991910: MUT-III Main Harness A
- MB991813: SWS monitor kit
- MB991806: SWS Monitor Cartridge
- MB991812: SWS Monitor Harness (For Column-ECU)
- MB991822: Probe Harness
- MB991854: SWS Monitor Harness (For 13-pin)

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.




1. Connect scan tool MB991958 to the data link connector (16-pin).
2. Connect SWS monitor harness MB991854 to the data link connector (13-pin).
3. Turn the ignition switch to the "LOCK" (OFF) position.
4. Operate the scan tool MB991958 according to the procedure below to display "ECU COMM CHECK."
a. Select "SYSTEM SELECT."
b. Select "SWS."
c. Select "SWS MONITOR."
d. Select "ECU COMM CHK".

5. Scan tool MB991958 should show "OK" on the "ECU COMM CHK" 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 the column switch (column-ECU) is not possible."

STEP 2. Replace the ECU.

1. Replace the column switch (lighting and turn-signal light switch).
2. If the functions, which are described in "CIRCUIT OPERATION", work normally, the input signal from the column switch (lighting and turn-signal light switch) should be normal.

Q: Does the column switch (lighting and turn-signal light switch) send normal signal to the ECU?

YES: No action is necessary and testing is complete.

NO: Replace the ETACS-ECU. If the functions, which are described in "CIRCUIT OPERATION", work normally, the input signal from the column switch (lighting and turn-signal light switch) should be normal.