HyperFlash Troubleshooting for 2005 BMW X3 Towing Trailer with LED Lights

Question:

I just installed the curt class III hitch and decided to go with BMW wiring harness since all BMWs in the e83 generation are pre-wired for it, no need to splice. The wiring harness has a trailer moduleinch no idea what this does in the harness package so this might be the issue. I am getting both a pulse when no signal is activated ie. just sitting no brakes no indicators. The pulse is really low but steady. When I use my indicators I get a hyper- flash. I What shall I do? I no longer have access to the the trailer led lights to add resistors for each light bulb well not without doing a major demo. Can I add a relay or trick it somehow? Your post said I shouldnt have trouble but I am or maybe I misread it? Trailer lights work perfectly on the 2016 Toyota Tacoma but I am assuming thats because its all LED. Please help.

asked by: Trinity K

Expert Reply:

German vehicles with factory wiring that do not want to work right with LED trailer lighting require the adapters # C57003 for a 7-way to 7-way or part # C35FR for 7-way to 4-way.

These adapters have the diodes wired into them so you would not need to hardwire additional ones in. The issue is that German vehicles have sensors built into the taillight harnesses to detect when a bulb has burned out. Since LED trailer lights only put a very slight amount of draw on the taillight circuits they think that a bulb has blown out. Using an adapter like what I referenced allows the circuit to have the same amount of draw on the circuit that incandescent bulbs put on it which allows the vehicle to not have the error message.

expert reply by: Jameson C