Inspection Procedure G-4

INSPECTION PROCEDURE G-4: Windshield Wiper and Washer: Windshield intermittent wiper interval cannot be adjusted.

TECHNICAL DESCRIPTION (COMMENT)
The ETACS-ECU calculates the intermittent wiper interval from the following input signals, and sends a signal to the front-ECU through the SWS communication line.
If the signal is defective, the front-ECU will ignore the signal and set the intermittent wiper interval to four seconds.

TROUBLESHOOTING HINTS
- The column switch (windshield wiper and washer switch) may be defective.
- The ETACS-ECU may be defective.
- The front-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: Test Harness Set
- MB991502: Scan Tool (MUT-II)
- MB991529: Diagnostic Trouble Code Check Harness

STEP 1. Check method of the input signal

Q: Which is to be used, the scan tool or a voltmeter to check the input signal?
Scan tool MB991502 : Go to Step 2.
Voltmeter : Go to Step 3.

STEP 2. Check the input signal (by using scan tool MB991502).
Check the input signals from the windshield intermittent wiper interval adjusting knob.

NOTE: If the windshield intermittent wiper interval adjusting knob is rotated from "FAST" to "SLOW when the ignition switch is at the "ON" position, the ETACS-ECU will send a signal around the medium knob position.

CAUTION : To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.




1. Connect scan tool MB991502 to the data link connector.
2. Check that the tone alarm of scan tool MB991502 sounds when the input signal enters.

Q: Does the tone alarm of scan tool MB991502 sound when the input signal enters?

YES : Go to Step 4.

NO : Check the revelent input circuit. Diagnosis By Symptom

STEP 3. Check the input signal (by using a voltmeter).
Check the input signals from the windshield intermittent wiper interval adjusting knob.

NOTE: If the windshield intermittent wiper interval adjusting knob is rotated from "FAST" to "SLOW" when the ignition switch is at the "Opposition, the ETACS-ECU will send a signal around the medium knob position.




1. Use special tool MB991529 to connect a voltmeter between ground terminal 4 or 5 and ETACS-ECU terminal 9 of the data link connector.
2. Check that the voltmeter indicator deflects once when the input signal enters.

Q: Does the voltmeter indicator deflect?

YES : Go to Step 4.

NO : Check the revelent input circuit. Diagnosis By Symptom

STEP 4. Replacement of ECU
1. Replace the front-ECU.
2. The windshield intermittent wiper interval should be changed.

Q: Is it possible to adjust the windshield intermittent wiper interval?

YES : No action is necessary and testing is complete.

NO : Replace the ETACS-ECU. The windshield intermittent wiper interval should be changed.