Step 1. ECU check on 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.

• Ignition switch: OFF

ECUS TO BE CHECKED

• COLUMN ECU

• FRONT ECU

OK: "OK" are displayed for all the items

Q: Are the check result normal?

"OK" are displayed for all the items:  Go to Step 2.
"NG" is displayed on the "COLUMN ECU" menu.:  Refer to Inspection Procedure A-2 "Communication with the column switch (column-ECU) is not possible" .
"NG" is displayed on the "FRONT ECU" menu.:  Refer to Inspection Procedure A-4 "Communication with the front-ECU is not possible" .

Step 2. Function diagnosis by using the SWS monitor

Check the SWS communication signal, which is related to the tail lamps.

<Selected item> LIGHTING - TAIL LAMP

• Ignition switch: ON

• Lighting switch: TAIL

Item No.	Item name	Normal conditions
Item 00	HEADLAMP SW	OFF
Item 01	TAIL LAMP SW	ON
Item 03	PASSING SW	OFF
Item 30	IG SW(IG1)	ON
Item 35	HD AUTO-CUT	OFF

OK: Normal conditions displayed for all the items

Q: Are the check result normal?

Normal conditions are displayed for all the items.:  Go to Step 3.
Normal condition is not displayed for item 00, 01 or 03.:  Refer to inspection procedure P-5 "The column switch (lighting and turn-signal lamp switch) signal is not received ."
Normal condition is not displayed for item No.30.:  Refer to inspection procedure P-2 "The ignition switch (IG1) signal is not received ."
Normal condition is not displayed for item No.35.:  Refer to Inspection Procedure K-6 "The headlamp automatic shutdown function does not work normally ."

Step 3. Connector check: A-11X front-ECU connector

Q: Is the check result normal?

YES:  Go to Step 4.
NO:  Repair the defective connector.

Step 4. Measure the voltage at A-11X front-ECU connector.

1. Remove the front-ECU, and measure at the relay box side.

2. Voltage between A-11X front-ECU connector terminal No.7 and body earth
OK: Battery positive voltage

Q: Is the check result normal?

YES:  Go to Step 6.
NO:  Go to Step 5.

Step 5. Check the wiring harness between A-11X front-ECU connector terminal No.7 and the battery.

• Check the power supply line for open circuit.

Q: Is the check result normal?

YES:  The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
NO:  Repair the wiring harness.

Step 6. Retest the system.

Check that the tail lamps illuminate normally.

Q: Is the check result normal?

YES:  The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
NO:  Replace the front-ECU.