Troubleshooting No Trailer Lights Working and Hopkins Tester Showing Multiple Functions Active
Updated 04/04/2019 | Published 04/03/2019
Question:
My travel trailer lights running lights and brake lights are no longer working. A couple days ago I had confirmed they worked when beginning a tow and sometime mid-drive they went out. There was some wet/snowy weather so I suppose its possible water got in somewhere and messed with a connection, but days later and still issues after trying multiple ways to troubleshoot. First, all truck lights are working on their own. I have validated the truck fuses are good visual confirmation referring to the owners manual for their confirmation checks and function - Focused on the Towing fuses. I have a Hopkins 7 way with LED display. The LEDs are lit basic connection is good between trailer and truck but the results are unexpected. I used https://www.youtube.com/watch?v=Lpxze9XzC24 for understanding what to expect on the Hopkins Display. The Hopkins display is as follows: TM EB BJ LT RT AX I am expecting the following on the Hopkins display to happen based on that video: - no lights on truck = AX lit - LT signal on truck = LT blink - RT signal on truck = RT blink - Hazard lights on truck = LT and RT Blink - Lights on truck = TM lit Instead, I observe the following: - no lights on truck = AX lit - LT signal on truck = TM, RT, and LT blink AX solid - RT signal on truck = TM, RT, and LT blink AX solid - Hazard lights on truck = TM, RT, and LT blink AX solid - Lights on truck = TM, RT, LT, and AX solid Definitely different behavior from the video. I cant understand why TM, RT, and LT all blink for a turn signal. I cant understand why all are lit when the truck lights are on. And, I cant understand why nothing is lit at all on the trailer when the LED display shows good connection. I have a suspicion the issue is on the truck side of this connection like wires are touching, but I can not see a problem with the truck. Please advise.
asked by: JoshF
Expert Reply:
The LED lights that are appearing on the Hopkins 7-Way # HM48503 are at least letting you know that power is reaching the 7-Way on your truck. The strange part as you mentioned is that it is essentially indicating that all lighting functions are being powered with any single function activated on the Tacoma.
This along with the fact that none of the lights on the trailer are working means that your best option at this point is going to be to first manually test the 7-Way on the truck side with a circuit tester like # PTW2993. Test each pin on the 7-Way individually, one at a time, while you have a buddy activate the corresponding function in the truck. Make sure you get power at the appropriate pin and that you aren't getting power on the others.
If you get similar results to what the Hopkins Connector was showing (power going to multiple pins for a single function like left turn signal) then there is likely a short somewhere on the truck side. You will want to inspect the 7-Way itself for any debris or corrosion that might be built up around and inside the pins, cleaning out as needed. Also try and inspect any wiring that you can gain access to behind the connector to make sure there aren't any pinched or exposed areas.
If manually testing the 7-Way reveals that everything is working as it should, then the issue is on the trailer side. You will want to start by inspecting the trailer side 7-Way for debris/corrosion. Then make sure its main ground is securely attached to a clean, bare metal surface.
If after this you are still unable to locate and resolve the issue, please let me know and we can continue to troubleshoot.
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