Could Roadmaster Diode be Used to Power Auxiliary Vehicle Lights on Front of Vehicle
Updated 07/24/2025 | Published 05/03/2025
Question:
Not knowing of your response here, I recently posed the question to RoadMaster and was told that I should not have power going to both inputs of the RoadMaster Hy-Power diode at the same time. My use would be, on a Ford F350 Limited, if that makes a difference having one input powered by an Upfitter switch Switch A, and the other input being powered by a separate Upfitter switch Switch B. The output goes to a pair of auxiliary LED lights on the front of the vehicle. If Switch A is on then the auxiliary lights are on. If Switch B, which runs through a relay is on, the auxiliary lights will only come on if the relay is triggered by a feed from the high beam headlight circuit. It is conceivable that both Switch A and Switch B could, inadvertently, be turned ONinch at the same time, and I dont want amps flowing back into the headlight high beam circuit. Could you verify whether your information is correct, that the diode would not allow current to flow backward if both switches are in the ONinch position and my intended use is fine, or whether RoadMaster is correct and I should not use the Hy-Power as I intend?
asked by: Jeff H
Expert Reply:
Hey Jeff, I don't see why you could use the Roadmaster diode part # RM-790 the way you mentioned. Sounds like you are looking for a way to have aux lights come on with either a remote switch from your cab or to come on anytime the high beams are on which this diode could work for that. This would also prevent backfeeding to the headlight circuit as well like you mentioned.
Product Page this Question was Asked From
Roadmaster Hy-Power Diode - (Qty 1)
- Accessories and Parts
- Flat Tow Wiring Harness
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Jeff H.
7/24/2025
In another post on eTrailer, it was stated these diodes are rated for up to 24V and can carry up to 85A. I connected one to a pair of LED auxiliary lights that were pulling about 8A. After 15-minutes of continuous use, the output side of the diode was at 140 degrees. If the diode is going to run that hot, shouldn't it be attached to a heat sink to draw some of that heat away so it doesn't damage the diode?