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Brake Lights are Dim With Turn Signal Flashing Using Converter 118158 On a Trailer


1994 GMC K2500 / 1997 Ford Ranger primary tow vehicles I have this converter TowReady #118158 currently wired to my trailer I really wanted amber turn signals and very much like it, and would like to purchase another one but have a few questions and a possible issue. First, the possible issue: I originally purchased this a few years ago and a few months ago noticed my brake lights red dim substantially when the turn signals amber are on, not quite to regular running light brightness, but noticeably dimmer. To put it another way, they basically flash with the turn signals. Im unfortunately unsure if it did this from the start and I just didnt notice it until recently. I cant tell any difference in the turn signal amber bulb / incandescent brightness with the brakes on or off. Without the turn signals the running/brake brightness is quite distinct and steady, and has no problems, nor complaints in that particular aspect. Ive done a fair share of wiring things and Im quite certain I hooked the wires up correctly, the sticker on the converter makes it pretty dang clear which wire goes to what. When I installed the converter the trailer already had LED brake lights I re-used them obviously, but I purchased regular incandescent amber turn signals for the project. I noticed it says it Will not work with vehicles that have LED taillights I didnt notice that at the time of purchase. Is the LEDs why my brake lights dim? Is there a version with an aux-battery power supply like from a 7-way plug that could give it some extra amperage? Would going to all incandescent bulbs help? Is there a problem with my converter? Is it just the current draw of the incandescent turn signals? Should I have installed the diodes? I didnt really think I needed to with a trailer application Whew, I think the covers everything. Generic use question: I was hoping to use this on another trailer Id like to build with all LED lights, including a 3rd brake light, is there a better/more-suitable converter for this? Would all incandescent be better? Last minute edit: Just re-read the features on the converter and thought I could have mis-interpreted things. Neither the GMC or the Ford Ranger have LEDs installed in their tail lights. They both have regular incandescent bulbs. Ive seen a couple use this for strictly trailer use in the reviews/questions, and they dont seem to mention this particular issue. Thank you the great service over the years, Ill be ordering a bunch more stuff in the late fall for the new trailer build.


Expert Reply:

The LED light warning is in reference to flat towing a vehicle that has LED lights. So basically for your situation the trailer (vehicle) LED lights could be the issue. An easy way to determine if it works better with incandescent bulbs would be to replace an LED brake light with an incandescent light of some kind and see if the problem persists.

If it does persist then the issue could be related to the fact that converter # 118158 is not rated very high. This is just the nature of this converter since it was meant for flat towing setups where amperage draw isn't very high. I do recommend checking the wiring to make sure there are no pinched or broken wires or corrosion on the trailer connectors that could be causing the issue.

To use it with a third brake light set up I do recommend sticking with incandescent bulbs.

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