Trailer brakes issue.

[Classic-Al]

Hi guys. Got 2000 Z-71 K1500 std cab, short bed. 4.8l
Tekonsa/Reise brake control unit ("brake-even"). Works fine until parking lights or drive lights activated. Then trailer brakes will drag. Wheb cranked down to "0" gain, no drag. Also, no brakes. The more gain I use, the more drag. (Using factory connector from dash to control unit.) Daytime driving, no problem. Nighttime, NG.
Any ideas?
Classic-Al.

 

[Cadillacmak]

That's an odd one, I don't know but it will be interesting to find out if someone else knows.

 

[ORVietVet]

Do you per chance use LED lights? Seems like every time some uses LED's, there is voltage and ground feedback problems.

 

[Classic-Al]

Truck has an "aftermarket" flatbed on it for now. I'd have to check all the lights, to be sure, but it's a thought. I'll have a chance to mess with it some more, tomorrow. In detail! (Check all connections/grounds).
Thanks.

 

[Classic-Al]

Got a little more feedback on this; first, no LEDs on truck. Yes, on trailer (new, 2 yr old). Decided to measure voltages under varying conditions; the fuse panel connector under left side of dash is starting point. Note the trailer was not connected for this test. Four wires at the trailer (jumper) connection, blue=trailer brakes. red=stop light, blk=power, wt=grnd. Voltage measurements at blue wire as follows:
1) at panel, lights off, trailer control disconnected, 7v
2) at panel, lights on, trailer control disconnected, 7v
3) at trailer connector (on bumper), w/trailer control disconnected, lights off, 7v
4) at trailer connector, w/trailer control disconnected, lights on, 7v
5) at trailer connector, w/trailer control connected, lights off, 0v
6) at trailer connector, w/trailer control connected, lights on, "0" gain, 0v
7) at trailer connector, lights on, increase gain to "5", 1.6v
8) at trailer connector, lights on, increase gain to "7", 2.2v
9) finally, at trailer connector, lights off, gain at "7", 0v.
All these figures are without activating the brakes or brake pedal. Go figure.
Also, removed all the light bulbs from the bed, then disconnected the entire bed circuit from the truck, just to be sure. Got same results as above. And.. initially disconnected the fuse panel jumper from the system, checked the "blue wire" terminal, and got 7v. (Is this normal?) All by itself.
So; bottom line, right now I can tow normally, and reliably if I don't turn on any lights. Note, signals or brake lights don't affect it, and it's normal.
So: any ideas? What am I missing here? Got a head-scratcher, for sure.
Thanks, Classic-Al.

 

[AuroraGirl]

 

[Classic-Al]

Thanks, I was aware that there was a running change in these trucks w/respect to the trailer wiring. Just wasn't sure what it was. I'll chase this down, next couple days. Big thanks! Classic-Al.

 

[Classic-Al]

One of the things that bothers me about this situation is the constant 7v (more or less) signal at the blue trailer brake wire (and terminal) under the dash. Is there supposed to be a trace signal here? Don't think so. I'll have to dig up an under-dash schematic and study it. Thanks, all. Classic-Al.

 

[Classic-Al]

Well, guys, (and gals) I chased this situation down, and found that the connector that i have (from Tekonsha) is intended for the '03-'06 truck. So, I ordered the connector for the '00-'02 truck. Should be in Tues/Wed and I'll see if this one works properly. Let you all know on this. Thanks, Classic-Al.

 

[Classic-Al]

I should also make a note, here, that I had originally assumed that i was using the factory connector, but was wrong on that one. It's a Tekonsha. (just to be clear). Thanks.

 

[Cadillacmak]

Glad you found the problem, hope it saves the next guy time.

 

[AuroraGirl]

I think the trucks only come with the blunt cut if the truck is ordered with a hitch , but a ball hitch(bumper) wouldn’t unless it was equipped a certain way. But no Chevy harness would come with a proper end on the plug so if youurs is a one piece assembly then it would be aftermarket

Glad my tsb could help

 

[Classic-Al]

Yep, that's right. Got the new connector harness yesterday, did a quick hookup, and it looks like it might work. After testing, can find no trace voltage at the trailer (brake circuit) connection. Will finish reinstalling the controller today, hopefully, and then test it out on the trailer. Only difference is one relocation of a wire. (Yes, I could have just moved one wire! But I wanted to be sure.) At the connection panel under the dash, I have noticed that where the trailer "jumper" connection goes, there are five terminals, but only four are used. At least in this application. Wonder what the fifth is for?
Anyway, I'll chime back in later after I finish it.
Classic-Al

 

[Classic-Al]

It worked! Finished the re-install, tested it in the garage, then hooked it up to the trailer and it all seems to work just fine. No activation at the trailer brakes when any of the lights are on, including signals or 4-way flashers. So, it turns out it was the connector after all. Well, I learned a lot in the process. (Mostly, try not to "overthink" the issue!) Thanks, all, for your help. It steered me in the right direction.
CA