Inspection Procedure 12: The stop lamp switch signal is not received.

caution

Before replacing the ECU, ensure that the power supply circuit, the earth circuit and the communication circuit are normal.
When the ETACS-ECU of vehicles without KOS is replaced, the encrypted code of the ignition key needs to be registered to the ETACS-ECU. (If the encrypted code is not registered, the engine cannot be started. Register the encrypted code as described in Immobilizer System - How to Register Key ID .)

COMMENTS ON TROUBLE SYMPTOM

The stop lamp switch input signal is used for the operation judgment of the functions below. If the signal is abnormal, these functions will not work.

ABS, ASC
Shift lock mechanism
OSS
Cruise control system

PROBABLE CAUSES

Malfunction of stop lamp switch
Malfunction of stop lamp relay^*
Malfunction of ETACS-ECU
Damaged harness wires and connectors

note

^*: The stop lamp relay cannot be inspected because it is a semiconductor relay.

DIAGNOSIS PROCEDURE

STEP 1. Check the stop lamp switch.

Check the stop lamp switch. Refer to GROUP 35A - Brake Pedal

Q. Is the check result normal?

Go to Step 2.

Replace the stop lamp switch.

STEP 2. Voltage measurement at ETACS-ECU connector (BKLP terminal).

(1)Measure by backprobing without disconnecting the ETACS-ECU connector and stop lamp switch connector.

(2)Check the voltage between the ETACS-ECU connector (BKLP terminal) and body earth.
OK:
When the brake pedal is released: Approximately 0 V - 5 V (pulse)
When the brake pedal is depressed: Approximately system voltage

Q. Is the check result normal?

Go to Step 5.

Go to Step 3.

STEP 3. Check of short to power supply, short to earth, and open circuit in BKLP line between ETACS-ECU connector and stop lamp switch connector.

Q. Is the check result normal?

Go to Step 4.

Repair the connector(s) or wiring harness

STEP 4. Check of short to power supply, short to earth, and open circuit in STP line between ETACS-ECU connector and stop lamp switch connector.

Q. Is the check result normal?

Go to Step 5.

Repair the connector(s) or wiring harness

STEP 5. M.U.T.-III data list

Temporarily replace the stop lamp relay, and then depress the brake pedal.

Item No.	Item name	Normal condition
Item 290	Stop lamp switch	ON

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.