Brake lights remain on - Accessories run when brake pedal pressed

chrisslondon

New member
Hello All,

I have a 2005 Sprinter 3500 (Freightliner) that carries a Gulf Stream Vista Cruiser Mini motorhome.

This winter on January 8, 2018 I noticed the brake lights on the motorhome. I had used it December 18-20 2017 and nothing was out of the ordinary then. I couldn't figure it out then so simply removed the wires from the light bulb assembly as I couldn't figure out what fuse to pull.

I took it to the mechanic on April 9th after replacing the brake light wires so I could drive it safely. No brake lights showed then and also the brake lights did not light when the brake pedal was pressed. The mechanic found a broken wire in a maze of wires that are part of the Signal/Brake system installed to allow for North American trailers to plug in.

After using the motorhome on April 13th, I noticed the brake lights on again the next morning. When I press on the brake pedal, the heater fan begins to run and the dash lights light up. That's a bit weird. If anyone can offer help with this problem, I will be more than pleased as the Sprinter goes to the mechanic next Monday.

If I have posted in the incorrect forum, please help me get it to the right place.

Thanks,
Rob
 

Aqua Puttana

Poly - Thread Finder
... The mechanic found a broken wire in a maze of wires that are part of the Signal/Brake system installed to allow for North American trailers to plug in.

...
Rob
That sounds like an OEM trailer light system. There is some history of a cluster of relays becoming wet and causing odd problems. I believe that the relays are stuffed into the right rear pillar. I think that there is at least one thread with pictures.

Couldn't find it though.

Here's one related to NCV3.

Brian, we were informed by our neighbor last night that one of our tail lights was on. I went to check it out and sure enough the left light was on, so I disconnected the batter, TA DAAA the light and everything else went dark. Connected the battery again and the light came back on, disconnected the battery again and went inside. Today I checked this great site and found your message. Went to our 2007 NCV3, found the 3" plug and pulled the DRIPPING wire harness out. I then found the drain hole and got out of the way of the steady stream of water. I connected the battery again and found one of the relays was warm, not hot AND the light did not come on unless directed by the light switch. Thank you so much for your message!
vic
 

chrisslondon

New member
Thanks Vic for this lead. Water on electric wiring or relays could well be a culprit. It was raining on Friday evening when I was driving.
 

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