Inspection Procedure 1: The Tail Lamps do not Illuminate Normally.



caution Whenever the ECU is replaced, ensure that the input and output signal circuits are normal.






COMMENTS ON TROUBLE SYMPTOM


If all the tail lamps do not illuminate, the tail lamp switch input circuit or the front-ECU may be defective.

PROBABLE CAUSES




DIAGNOSIS PROCEDURE


STEP 1. ECU check by using the SWS monitor.


Check that the power supply and earth lines to the column switch (column-ECU) and the front-ECU and the SWS communication lines are normal.

ECUS TO BE CHECKED
OK: "OK" are displayed for all the items

Q. Is the check result normal?

YES ("OK" are displayed for all the items) : Go to Step 2.

NO ("NG" is displayed on the "COLUMN ECU" menu) : Refer to GROUP 54C - Trouble Symptom Chart .

NO ("NG" is displayed on the "FRONT ECU" menu) : Refer to GROUP 54C - Trouble Symptom Chart .

STEP 2. Function diagnosis by using the SWS monitor.


Check the SWS communication signal, which are related to the tail lamps.
<Selected item> LIGHTING - TAIL LAMP
Item No.
Item name
Normal condition
Item 00
HEADLAMP SW
ON when the lighting switch is at HEAD
Item 01
TAIL LAMP SW
ON when the lighting switch is at TAIL
Item 03
PASSING SW
OFF
Item 30
IG SW(IG1)
ON
Item 35
HD AUTO-CUT
OFF
Item 70
FRONT ECU ACK
NORMAL ACK
OK: Normal conditions are displayed for all the items

Q. Is the check result normal?

YES (Normal conditions are displayed for all the items) : Go to Step 3.

NO (Normal condition is not displayed for item Nos.00, 01 or 03) : Refer to ETACS - Input Signal Chart .

NO (Normal condition is not displayed for item No.30) : Refer to ETACS - Input Signal Chart .

NO (Normal condition is not displayed for item No.35) : Refer to Headlamp - Inspection Procedure 6 "The headlamp automatic-shutdown function does not work normally .

NO (Normal condition is not displayed for item No.70) : Replace the front-ECU.

STEP 3. Connector check: A-08X front-ECU connector


Q. Is the check result normal?

Go to Step 4.

Repair the defective connector.

STEP 4. Voltage measurement at A-08X front-ECU connector.


(1)Remove the front-ECU, and measure at the relay box side.
(2)Voltage between A-08X front-ECU connector terminal Nos.3, 4, 5 and body earth
OK: System voltage

Q. Is the check result normal?

Go to Step 6.

Go to Step 5.

STEP 5. Check the wiring harness between A-08X front-ECU connector terminal No.3, 4, 5 and the battery.



Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).

Repair the wiring harness.

STEP 6. Retest the system.


Check that the tail lamps illuminate normally.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).

Replace the front-ECU.