Trailer Lighting Control Unit Input Test (2017 2018 2019)

NOTE: 

• Before testing, check for DTCs. If any DTCs are indicated, troubleshoot those DTCs first.
• If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A .
• Before testing, make sure the fuses associated with the system is OK.

1. Turn the vehicle to the OFF (LOCK) mode.

2. Disconnect the trailer lighting control unit 12P connector.

TRAILER LIGHTING CONTROL UNIT 12P CONNECTOR (female terminals) 

Courtesy of HONDA, U.S.A., INC.

3. Inspect the connector and socket terminals to be sure they are all making good contact:

• If the terminals are bent, loose, or corroded, repair them as necessary, and recheck the system.
• If the terminals are OK, go to step 4.

4. Reconnect the connector, and do the following input tests:

• If any test indicates a problem, find and correct the cause, then recheck the system.
• If all the input tests prove OK, replace the trailer lighting control unit .

Cavity	Wire	Test condition	Test: Desired result	Possible cause if desired result is not obtained
3	WHT	Under all conditions	Measure the voltage to ground: There should be battery voltage.	An open or high resistance in the wire
6	ORN	Under all conditions	Measure the voltage to ground: There should be battery voltage.	An open or high resistance in the wire
7	BLK	In all power modes	Measure the voltage to ground: There should be less than 0.2 V.	Poor ground (G602) An open or high resistance in the ground wire
8	BLK	In all power modes	Measure the voltage to ground: There should be less than 0.2 V.	Poor ground (G602) An open or high resistance in the ground wire
12	ORN	Brake lights ON state	Measure the voltage to ground: There should be battery voltage.	Faulty brake light relay An open or high resistance in the wire
11	BLU	Right turn signal light ON state	Measure the voltage to ground: There should be battery voltage.	Faulty MICU An open or high resistance in the wire

Cavity	Wire	Test condition	Test: Desired result	Possible cause if desired result is not obtained
5	GRN	Left turn signal light ON state	Measure the voltage to ground: There should be battery voltage.	Faulty MICU An open or high resistance in the wire
2	BLU	Under all conditions	Measure the voltage to ground: There should be battery voltage.	Faulty trailer lighting control unit An open or high resistance in the wire
9	WHT	Brake lights ON state and/or left turn signal light ON state	Measure the voltage to ground: There should be about 5 V.	Faulty trailer lighting control unit An open or high resistance in the wire
10	RED	Brake lights ON state and/or right turn signal light ON state	Measure the voltage to ground: There should be about 5 V.	Faulty trailer lighting control unit An open or high resistance in the wire