Inspection Procedure 13: The rear window defogger switch signal is not received. <vehicles with automatic air conditioner>


caution Whenever the ECU is replaced, ensure that the input signal circuit is normal.

COMMENTS ON TROUBLE SYMPTOM


Input signal from the rear window defogger switch is used to operate the functions below. If the signal is abnormal, these functions will not work normally.

PROBABLE CAUSES



DIAGNOSIS PROCEDURE


STEP 1. M.U.T.-III data list for other systems


Check the A/C-ECU system data list.

Item No.
 Item name
 Normal condition
60
 Rear defogger switch
 OFF to ON (only when switch is operated)

Q. Is the check result normal?

Go to Step 2.

Replace the auto A/C controller assembly.

STEP 2. Check of short to power supply, short to earth, and open circuit in DFSW line between ETACS-ECU connector and auto A/C controller assembly (A/C-ECU) connector


Q. Is the check result normal?

Go to Step 3.

Repair the connector(s) or wiring harness.

STEP 3. M.U.T.-III data list


Check the ETACS-ECU system data list.

Item No.
 Item name
 Normal condition
103
 Rear defogger switch
 OFF to ON (only when switch is operated)
OK: Normal condition is displayed.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).

Replace the ETACS-ECU.