Diesel Data: Automotive Repair

Taillight Relay Circuit








LIGHTING: LIGHTING SYSTEM: Taillight Relay Circuit

Taillight Relay Circuit

DESCRIPTION

The main body ECU controls the T-LP relay when a signal is received from the combination switch.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. PERFORM ACTIVE TEST USING TECHSTREAM (TAILLIGHT)
(a) Select the ACTIVE TEST, use the Techstream to generate a control command, and then check that the taillight illuminates.

Main body ECU





OK:
Each light comes on.
OK -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
NG -- Continue to next step.

2. CHECK DRIVER SIDE JUNCTION BLOCK (MAIN BODY ECU)




(a) Measure the voltage of the connectors.
Standard voltage:






OK -- REPAIR OR REPLACE HARNESS AND CONNECTOR (EACH TAILLIGHT CIRCUIT)
NG -- Continue to next step.

3. CHECK WIRE HARNESS (ECU - BATTERY)




(a) Disconnect the 1B junction block connector.
(b) Measure the voltage of the wire harness side connector.
Standard voltage:






NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE