2007 topper brake light wiring issue

[agff]

Have a 2007 Mega 1500 I just got in April (week after picking up a 04 CTD 2500 reg cab). Found a matching leer topper to put on it and am trying to wire up the brake light.

Found a single wire outside the loom behind the spare where it comes down to the trailer plug area. Wire has 12 volts when brakes are on, (checked with volt meter) and lights up a test light. Attached a pigtail to it running up into the bed with a two pole disconnect. At the disconnect I have 12 volts and will light a test lamp. when I hook the brake light to it I get nothing. Bought a new brake light (LED) and when wire leads are placed directly to a 12v battery it lights up, when I hook it to the two prong lead - nothing.



Any ideas? Got me stumped!

 

[Missouri Mule]

Your TIPM mite not like the extra power being used.

Try putting a relay between the brake light wire and the brake light (have the brake light wire turn the relay on and have 12 volts direct from battery supply the power).

 

[HBarlow]

The camper shell is made of non-conductive fiberglass. I don't think your lamp has no ground return. You'll need to ground it.

 

[agff]

Could you explain what "TPIM" stands for / what that wire is intended for?



I have a relay that I could use back there and just tap into the 12V + feeding the trailer 7 prong in the loom behind it if I need to.



Kind of surprised that a 4-5 LED light would draw enough to matter though.

 

[agff]

The lamp has a two wire (blk/red) lead - when hooked to a separate battery it lights up fine, and i have one of them running to the chassis underneath (made a fresh ground on the chassis and brought it up with the wire I hooked onto for the feed power.

 

[Joseph Donnelly]

On newer trucks with the totally integrated power module (TIPM) you will find wires that seem to have 12 volts but they carry almost zero amps and are intended as signal wires, not load bearing wires. Splice into a brake light wire on the rear harness or the trailer wiring harness.

 

[HBarlow]

Hmmm. I don't understand. If the wire can flow sufficient current to light an ordinary incandescent bulb in a test lamp I would think it capable of lighting a four or five bulb LED lamp.

It might be worth trying a taillamp (not stoplamp) wire but I wonder if the TIPM will sense the additional current draw and open the circuit?

 

[agff]

Yea, I can't make sense of it either, test light ok, LED not? I guess the LED's could be totalling more ampreage to the point of being over the trigger point for that wire.



I'm going to just make a lead and try a 1156 bulb alone, and I always have a relay around for ag tractor projects so I'll give that a try as well.



I thought I had the "right" wire to use for a brake light since it was wrapped up / dead end sealed up outside of the main wiring loom, could there be another brake wire back there that I'm overlooking thats not part of the left/right turn signal circuits?

 

[mwilson]

Yea, I can't make sense of it either, test light ok, LED not? I guess the LED's could be totalling more ampreage to the point of being over the trigger point for that wire.



I'm going to just make a lead and try a 1156 bulb alone, and I always have a relay around for ag tractor projects so I'll give that a try as well.



I thought I had the "right" wire to use for a brake light since it was wrapped up / dead end sealed up outside of the main wiring loom, could there be another brake wire back there that I'm overlooking thats not part of the left/right turn signal circuits?

Is it White/ w Tan Stripe???



Go to page 6 of the attached PDF link. From Ram Body Builder site for 2007 Mega. Look for "Lamp CHMSL aftermarket" to the lower right of the page.



http://www.rambodybuilder.com/2007/docs/wd/dr/wiringdiagrams/8w51rearlighting.pdf



Hope this helps...



Mike.

 

[mwilson]

Is it White/ w Tan Stripe???



Go to page 6 of the attached PDF link. From Ram Body Builder site for 2007 Mega. Look for "Lamp CHMSL aftermarket" to the lower right of the page.



http://www.rambodybuilder.com/2007/docs/wd/dr/wiringdiagrams/8w51rearlighting.pdf



Hope this helps...



Mike.

Just thought of something else... MANY LED lights are polarity sensitive unlike normal lights. Reverse your wiring at the light to double check. I have had it happen to me as well.



Mike.

 

[crispyboy]

On my 09 I used this single wire for the third brake light on the truck cap - that is what it is for! Check out mwilsons body builders guide.
LED lights are have a definite polarity. You will need a ground wire. I tapped the trailer ground. If you tap the tail light then the third brake light will blink with the turn signal - which is a mistake.
I ran 3 wires up into the cap: ground, brake light and a 12v wire for interior LED lights and a power point to charge a cell phone etc...