Inspection Procedure 3

Inspection Procedure 3: Stoplight does not illuminate or go out normally.














COMMENTS ON TROUBLE SYMPTOM

If the stoplights do not illuminate or go out normally, the stoplight relay power supply, ground circuit system, stoplight switch, or the stoplight relay * may be defective.
NOTE:
*: The stoplight relay cannot be inspected because it is a semiconductor relay.

PROBABLE CAUSES

- Malfunction of stoplight switch

- Malfunction of stoplight relay

- Damaged harness wires and connectors

DIAGNOSIS

Required Special Tools:

- MB992006: Extra fine probe

- MB991223: Harness set

STEP 1. Check stoplight relay connector C-133 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is stoplight relay connector C-133 in good condition?

YES Go to Step 2.
NO Repair the damaged parts
STEP 2. Resistance measurement at stoplight relay connector C-133.

(1)Disconnect the connector, and measure at the wiring harness side.





(2)Measure the resistance between stoplight relay connector C-133 (terminal No. 8) and the body ground.
The measured value should be continuity exists (2 ohms
or less).

Q. Does the measured resistance value correspond with this range?

YES Go to Step 4.

NO Go to Step 3.

STEP 3. Check the wiring harness between stoplight relay connector C-133 (terminal No. 8) and ground.

Check the ground line for open circuit.

Q. Is the wiring harness between stoplight relay connector C-133 (terminal No. 8) and ground in good condition?

YES Go to Step 4.
NO Repair the wiring harness.
STEP 4. Check the stoplight switch.

Remove the stoplight switch.

- Check for continuity between the terminals of the switch.





Q. Is the stoplight switch in good condition?

YES Go to Step 5.
NO Replace the stoplight switch.
STEP 5. Check the battery power supply circuit to the stoplight relay.
Measure the voltage at stoplight relay connector C-133.

(1)Disconnect stoplight relay connector C-133 measure the voltage available at the wiring harness side of the connector.





(2)Measure the voltage between stoplight relay connector C-133 terminal 6 and ground.

- The voltage should measure approximately 12 volts (battery positive voltage).
(3)Stoplight
switch: ON





(4)Measure the voltage between stoplight relay connector terminal No. 2 and the body ground.

- The voltage should measure approximately 12 volts (battery positive voltage).

Q. Is the measured voltage approximately 12 volts (battery positive voltage)?

YES Go to Step 7.

NO Go to Step 6.

STEP 6. Check ETACS-ECU connector C-304 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is ETACS-ECU connector C-304 in good condition?

YES Go to Step 7.
NO Repair the damaged parts
STEP 7. Check the wiring harness between stoplight relay connector C-133 (terminal No. 2/6) and ETACS-ECU connector C-304 (terminal No. 1).

- Check the power supply line (battery supply) for open circuit and short circuit.

Q. Is the wiring harness between stoplight relay connector C-133 (terminal No. 2/6) and ETACS-ECU connector C-304 (terminal No. 1) in good condition?

YES Go to Step 8.
NO Repair the wiring harness.
STEP 8. Check ETACS-ECU connectors C-312 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is ETACS-ECU connectors C-312 in good condition?

YES Go to Step 9.
NO Repair the damaged parts.
STEP 9. Check the battery power supply circuit to the ETACS-ECU. Measure the voltage at ETACS-ECU connector C-312.

(1)Disconnect connector measure the voltage available at the wiring harness side of the connector.

(2)Disconnecting the ETACS-ECU connector C-312.

(3)Stoplight switch: ON





(4)Measure the voltage between ETACS-ECU connector C-312 terminal No. 16 and the body ground.

- The voltage should measure approximately 12 volts (battery positive voltage).

Q. Is the measured voltage approximately 12 volts (battery positive voltage)?

YES Go to Step 11.

NO Go to Step 10.

STEP 10. Check the wiring harness between ETACS-ECU connector C-312
(terminal No. 16) and stoplight relay connector C-133 (terminal No. 2).

- Check the signal line for short circuit.

Q. Is the wiring harness between ETACS-ECU connector C-312 (terminal No. 16) and stoplight relay connector C-133 (terminal No. 2) in good condition?

YES Go to Step 11.
NO Repair the wiring harness.
STEP 11. Check the wiring harness between stoplight relay connector C-133 (terminal No. 4) and intermediate connector C-131 (terminal No. 9).

Check the communication line for open or short circuit.

Q. Is the wiring harness between stoplight relay connector C-133 (terminal No. 4) and intermediate connector C-131 (terminal No. 9) in good condition?

YES Go to Step 12.
NO Repair the wiring harness.
STEP 12. Retest the system

Check that the stoplight illuminates normally.

Q. Does the stoplight relay work normally?

YES The trouble can be an intermittent malfunction How to Cope With Intermittent Malfunctions).
NO Replace the stoplight relay.