Inspection Procedure 26: Brake Monitoring Switch System <CVT>

OPERATION

Battery voltage is applied to the stop lamp switch from the engine-ECU connector terminal BRK.

FUNCTION

The brake monitoring switch detects whether the brake pedal is depressed or not, and sends a signal to the engine-ECU. The engine-ECU compares the stop lamp signal sent from the ETACS-ECU via the CAN with the brake monitoring switch input signal, and determines whether the input information is reliable. In addition, it sends the brake monitoring switch signal information to other ECUs (such as ETACS-ECU or CVT-ECU) via the CAN.

PROBABLE CAUSES

Failed brake monitoring switch
Open/short circuit or harness damage in brake monitoring switch circuit or loose connector contact
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check for height of brake pedal.

Check for height of brake pedal (Refer to GROUP 35A - On-vehicle Service - Brake Pedal Check And Adjustment ).

Q. Is the check result normal?

	Go to Step 2.

	Adjust.

STEP 2. Check the brake monitoring switch.

Check the stop lamp switch (Refer to GROUP 35A - Brake Pedal - Inspection - Stop Lamp Switch Check ).

Q. Is the check result normal?

	Go to Step 3.

	Replace the stop lamp switch.

STEP 3. Perform voltage measurement at brake monitoring switch connector

Disconnect connector, and measure at the harness side.
Ignition switch: ON
Voltage between terminal BRK line and earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 6.

	Go to Step 4.

STEP 4. Check of short to earth, and open circuit in BRK line between stop lamp switch connector and engine-ECU connector.

Q. Is the check result normal?

	Go to Step 5.

	Repair the connector(s) or wiring harness.

STEP 5. Check the trouble symptom.

Q. Does the trouble symptom persist?

	Replace the engine-ECU.

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 6. Check of open circuit, short circuit, and damage in earth line between stop lamp switch connector and body earth.

Q. Is the check result normal?

	Go to Step 7.

	Repair the connector(s) or wiring harness.

STEP 7. Perform voltage measurement at engine-ECU connector.

Measure engine-ECU terminal voltage.
Engine: Idling
Voltage between terminal BRK and earth.

OK:
1 V or less (Brake pedal: Released)
System voltage (Brake pedal: Depressed)

Q. Is the check result normal?

	Go to Step 5.

	Go to Step 8.

STEP 8. Check of damage in BRK line between brake monitoring switch connector and engine-ECU connector.

Q. Is the check result normal?

	Replace the stop lamp switch.

	Repair the connector(s) or wiring harness.