11 replies to this topic

[quetranpa]

I have to hook up the brake light on the camper shell but the brake lights on the truck all are stop/turn even the ones on the trailer wiring, so I think I can bring a wire from the truck's third brake light all the way to the camper brake light
this is what I'm trying to do: I want to tap a wire from the MBEC x9 pin 3 which is "Stop Lamp Supply Voltage signal" and bring it to the back of the truck to the camper shell brake light, I tested and this one doesn't blink with the blinkers but lights with the brake pedal


but I don't know if this is the right way to do it, I have been scratching my head trying to find an easy way to do this
any help is greatly appreciated guys!!! thanks

Edited by quetranpa, 17 April 2011 - 02:14 AM.

[MikeNH]

Isn't there a capped off wire near the 7 pin trailer plug that is specifically for a brake lamp on a top?

[quetranpa]

thanks mike you know you might be right,
I'm going to look under the truck and look for that wire 'cause it might be there, that is how the previous owner had it hooked up but I didn't have a chance to see it closely, we just cut the wire behind the brake light wondering why the people who hook it up did it right behind the 7 pin connector, until now that I want to hook it up is starting to make sense, so I will see if there is such a connector and let you guys know for all of those who want to do the same thing.
for what is worth I read about a guy who was pulling a trailer with electric brakes and he had some weird breaking in the trailer even without a trailer brake controller, until he found that the guy that hooked up his camper shell brake light had cheated, he some how got power on another wire in the 7 pin connector and hook up the shell brake light there, and that is exactly what I wanted to do but I had no luck when I attempted to do that, so I guess I will keep on looking, any other thoughts?

Edited by quetranpa, 17 April 2011 - 11:53 PM.

[montyss]

its the orange wire in the harness for the aftermarket trailer brake controller ,
TRUCK WIRING Trailer Brake Controller Side
Dk Blue - Aux--------------->Blue Wire Brake Output to trailer.
Red/Black - BATT----------->+ Black Wire Positive
LT Blue/WHT-CMHSL-------->
ORN - CHMSL---------------->X Red Wire
WHITE - GND- --------------->WHITE Wire Negative

[quetranpa]

thanks montyss but the problem is that I don't have a trailer brake controler, but what mikenh is saying makes sense and by the way another guy told me the same thing but I haven't have the chance to look under my truck and see if I find it!!!

[montyss]

its up there between the steering column and the park brake on trucks that do not have the factory brake controller , it has tape all over it and the blunt ends taped to

[quetranpa]

now wait a minute montyss, the wire that mikenh is talking about is not powered? so I guess that if I find it just behind the trailer plug in back of my truck I will find the other end of it inside the truck like you said and then plug it in the x9 pin 3 in the junction box? well that makes a lot of sense!!!!
I will look in to it this weekend since I have been busy all this week and will tell you the results!!!!
thanks

[quetranpa]

update: I was able to find the orange wire near the steering column and it has power already, yes it works with the brake pedal and it doesn't blink with the blinkers, I think that I will finally hook up a wire (with a 5 amp fuse) on that orange wire and run it all the way to the back of the truck and hook up the topper brake light to it
on the other hand I was able to find a plug in the same bundle of wires as the 7 pin trailer plug near the spare tire, but it has no power at all, and then I also found a similar plug right above the ebrake pedal, so I'm wondering if this is the other end of the wire near the spare tire, and I have to provide power to it and then just hook up my lights on the other end instead of running a new wire, here are some pics of the wires, I don't have a pic of the plug right above the ebrake pedal but I will post it asap

Edited by quetranpa, 14 May 2011 - 08:50 PM.

[montyss]

could it be for a truck that has rear park assist sensors or a trailer brake module (relay) ?

[quetranpa]

well I'm still trying to find the answer to that question
on the other hand I think I will run a new wire from the orange one by the knee booster all the way to the back of the truck and hook up the topper light on it since my inspection is now due and I don't feel like taking the topper off the truck just to pass inspection since the bed is full of tools
I will post the way I hook up the lights once I finally do it!!!

[Tucson_02Silverado]

This might not help since you're asking about a GMT-900.....
On the GMT-800 factory optioned towing harness, at the back of the 7-pin connector there is a capped light blue pigtail. That is the CHMSL circuit.


Also reference an official GM site for upfitters

Edited by Tucson_02Silverado, 02 June 2011 - 02:06 AM.

[quetranpa]

thank you "Tucson"
I'm looking at the website you suggested, hopefully I can get a clear answer
on the other hand I already run a wire from the orange wire by the steering wheel (like montys suggested) all the way to the back of the truck and to the brake light on the topper 'cause my inspection was past due, the truck passed inspection but I'm not happy with the wire I run, I know there's has to be a better way, the way upfitters do it at the truck accessories stores
I will post if I find the right way to do it for others to see