Problem with 3rd brake light on camper shell

[WKener]

Okay, here's the problem: I put on the shell late last week, and when I hooked up the 3rd brake light, I ran into a problem. I had the guys at the shop take a look at it also, and it is hooked up the same as all the others they have done: power from the main power lead on the left-rear brake light (labeled "Main"), and we ran a self-tapper to be positive that we have a good ground... all seems to work well when I put on the brakes, but if I hit the left turn signal, the 3rd light flashes with the signal. So we wired it up to the right taillight, and the same thing. I don't understand why there is power going to the 3rd brake light when the signal is on, there shouldn't be.

We are tapped into the brake lead, not the signal lead... when the brakes are on, the light works well, but if I use the signal at the same time, the light goes off and begins flashing.

I have replaced the flashers in the fuse panel, I am about to replace the actual brake light/signal/bulb assembly, but I am reluctant because it was the same on both sides of the truck. (I thought that maybe there was a problem in there, sending a pulse back with the turn signal, but I can't imagine both of them are bad)

Any ideas as to what I am doing wrong?

 

[Neal Cassady]

Try this

There should be a white wire with a purple tracer exiting the factory harness near the drivers side rear wheel under the bumper. Should be labeled



CHMSL



Use that to power the brake light on the cap. Works on my truck.



Dave

 

[illflem]

I was told by the fellow who installed my shell that on pre '98 Rams you have to run a wire all the way back to under the dash. That's what he did while *****ing about it, I'm sure if there was a easier way he would have known about since it didn't add to the cost of the shell. He was a very knowledgeable high volume installer. I personally haven't tried it any other way.

 

[Idaho Native]

When I had my shell installed on my '99, the CHMSL did exactly what yours was doing. I took it back to the shell dealer and he found that on '99s and newer, there is a wire in the factory harness to tap into for the stop lamp. He was told by D/C that the wire was factory installed on '99s and newer/2500 and up only. Otherwise, you'll have to do what illflem talked about. That's what the shell dealer was going to do to mine until he called the local Dodge boys... . I wasn't thrilled about another wire running along the frame.



Good luck.



Loren

 

[Dkevdog]

I just finished the exact same project so I could add additional brake lamps to some trailers. Mine is a 96- I would imagine yours is the same. The CHMSL wire does not exist in our wireloom as it does in the newer trucks. Illflem is right, the only way to do it is to run a wire all the way to the stoplight switch on the brake pedal. I ran mine to a relay becuase of the load of the additional lamps, but I would guess the load of a single lamp would be OK.



Kev

 

[WKener]

Thanks guys, I guess I will have to run it all the way back to the cab, no wonder I couldn't get it to work right...