operation abnormality of the taillight/stoplight function

1. Operation abnormality of the taillight/stoplight function diagnostics

1. Pre-check and visual inspection

1) Check the illumination status of the tail stoplight.

Confirm that the clearance light and license plate light illuminate.

2) Check for any interference from aftermarket electronic components such as two-way radios or lights.

Turn OFF or remove any aftermarket electronic components to ensure that there is no influence on inspections or operations.

2. Components inspection

1) Inspect the fuse.

If an abnormal condition such as a fuse blowout is found, inspect or repair the cause of the abnormal condition before replacing the fuse.

2) Inspect the taillight relay function.

If a malfunction is found in the relay, replace it.

3) Inspect the stoplight switch.

Refer to "4.Brakes 4B.Brake System stoplight switch inspection".

Replace the stoplight switch if a malfunction is found.

Refer to "4.Brakes 4B.Brake System stoplight switch removal".

Refer to "4.Brakes 4B.Brake System stoplight switch installation".

4) Inspect the tail stoplight bulb.

If any abnormal conditions are found in the tail stoplight bulb, replace it.

Caution

For models with LED tail stoplights, it is not possible to replace only the LED bulb.
When replacing the LED bulb, replace it as a set with the tail stoplight.

Refer to "9.Body, Cab, Accessories 9A.Lighting Systems tail stoplight bulb removal".

Refer to "9.Body, Cab, Accessories 9A.Lighting Systems tail stoplight bulb installation".

5) Inspect the BCM.

Observe the DTC information, and replace the BCM if a malfunction is found.

Caution

Perform programming after replacing the BCM.

Refer to "9.Body, Cab, Accessories 9Z.Body, Cab, Accessories Electrical Control BCM removal".

Refer to "9.Body, Cab, Accessories 9Z.Body, Cab, Accessories Electrical Control BCM installation".

Refer to "9.Body, Cab, Accessories 9Z.Body, Cab, Accessories Electrical Control BCM setting".

3. Circuit inspection

1) Check that the ground point is normal.

Repair or clean any ground points that are improperly installed or significantly dirty.

2) Check that the harnesses and connectors are normal.

Inspect for the following circuits for an open circuit, short, poor connections at the connectors, and abnormal conditions such as worn or bent harnesses.

Models with BCM

Between the BCM and the rear combination light
Between the BCM and the combination switch

Models without BCM

Between the fuse and the stoplight switch
Between the stoplight switch and the rear combination light
Between the rear combination light and the taillight relay
Between the taillight relay and the combination switch

Caution

When checking the continuity between the harnesses, disconnect the battery negative terminal.

Refer to "201.General Information 14A.Service Information Guide Preliminary and post procedures".