Trailer Wire Connector issue - Chevy Colorado & GMC Canyon
 
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post #1 of 11 (permalink) Old 05-03-2016, 06:39 PM Thread Starter
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Trailer Wire Connector issue

Hello All,
Last night after picking up my boat from the shop I noticed the trailer lights kept flickering. the lights seem to go in and out if I wiggled the connector at the truck but i'm thinking that could still mean truck or trailer.

Anyway, I believe this is due to a bad ground but am having a hard time narrowing it down to the trucks ground or the trailer.

I had trouble earlier this year and discovered that quite a few of the wires were at least somewhat damaged going from the I believe "converter box" to the harness 4way plug. I spliced them all with new heatshrunk splices.

This morning I hooked up a test light on the truck and all seemed to be happy maybe one of the turn signals i had to probe around a bit but not sure if that matters or means that's the issue as all the lights turn on just flicker in and out.

I started to look for the ground on the truck but I don't see it as it seems like most kits they sell have a ground wire coming out of the converter pack.

So can anyone tell me what tests I can further to to figure out if it's the trailer or the truck. Or can anyone tell me where to find the ground wire?

Thanks in Advance!
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'04 Colorado LS ext cab 5 cylinder
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post #2 of 11 (permalink) Old 05-03-2016, 07:02 PM
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Originally Posted by jessb_55 View Post
Hello All,
Last night after picking up my boat from the shop I noticed the trailer lights kept flickering. the lights seem to go in and out if I wiggled the connector at the truck but i'm thinking that could still mean truck or trailer.

Anyway, I believe this is due to a bad ground but am having a hard time narrowing it down to the trucks ground or the trailer.

I had trouble earlier this year and discovered that quite a few of the wires were at least somewhat damaged going from the I believe "converter box" to the harness 4way plug. I spliced them all with new heatshrunk splices.

This morning I hooked up a test light on the truck and all seemed to be happy maybe one of the turn signals i had to probe around a bit but not sure if that matters or means that's the issue as all the lights turn on just flicker in and out.

I started to look for the ground on the truck but I don't see it as it seems like most kits they sell have a ground wire coming out of the converter pack.

So can anyone tell me what tests I can further to to figure out if it's the trailer or the truck. Or can anyone tell me where to find the ground wire?

Thanks in Advance!
You're on the right track… If you're not blowing fuses sounds like a ground or contact issue at the plug (i assume you're talking about the 7 prong trailer plug on the bumper)

Can be a tedious procedure.

Don't know where the ground is, somewhere in the harness.

You can always run another ground splicing into the existing ground wire and grounding to a clean surface on the frame. Make sure you ground the right wire or you'll short it and blow a fuse…. or worse

If its occurring when you wiggle the plug, clean all the plug ends with some electrical contact cleaner (even WD40 and a hobby wire brush if necessary) and then apply that electrical grease.

For the bumper plug, If you're able to remove the plug, take the plug cover off to view where the wires connect to the plug internally. Check out the contacts. Vibration may loosen the wires or the wires may break causing a bad connection.

It can be a process of elimination and seriously make you question your sanity at times.

After looking at your pic, looks like you're using the logic box and a 4 or 5 prong flat plug. Same procedure except you won't have to take apart the 7 prong bumper plug.

Could be your Box. I've had a logic box go bad but no flickering, just lost a circuit of lights.

Looks like some corrosion down there. May be time to freshen it up and re-connect.

Good luck!

2016 Canyon SLT 2.8 Duramax 4x4 SBCC White

Last edited by Vinolush; 05-03-2016 at 07:10 PM.
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post #3 of 11 (permalink) Old 05-03-2016, 07:18 PM
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If you have the OEM harness with the 4 pin trailer connector, there are two white wires coming out of the converter. They are both ground wires. One goes aft to the trailer connector. The other wire goes to a splice, changes color to black, and goes forward to the ground splice pack, G105, in the engine compartment, left side aft of the battery. All of the lights on the rear of the truck ground at G105.

There have been a lot of problems with the OEM tow harness converter.

This is a picture of the ground G105. It would probably be a good idea to remove the one bolt and clean the contact surfaces of the box tab and the fender wall.

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post #4 of 11 (permalink) Old 05-03-2016, 09:51 PM Thread Starter
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thanks

Thanks so much for the responses. I am using a 4 prong plug. I'm starting to think that I have the OEM harness and that's why there is no ground wire to the frame. I'll look for corrosion, etc up at the front G105 ground pack. As for cleaning up the plug on the truck I did take a lot of contact cleaner, wire brush and dieletric grease to it as well, In fact several times last year f my memory serves me right I don't think I could get the trailer lights to work at times without dieletric grease. Like Vinolush mentioned this stuff can make a person crazy.... Last summer while on vacation I had my father in law hook up my boat to his truck and the lights worked fine....so I was starting to think it was definitely the truck especially cause there are many splice repairs between the converter and the trailer plug, but what throws me off is the fact that the ground light up my test light real well.



Cart7881 in terms of there being many issues with the OEM tow harness converter, can you elaborate some?

Vinolush, you mention some corrosion down there, which I agree but which area you referring to and would like me to clean up?

Thanks again!
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post #5 of 11 (permalink) Old 05-04-2016, 08:15 AM
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The problems posted were mostly related to the truck lighting, the brake lights and turn signals. I think the converter boxes were developing cracks and the electronics were exposed to moisture. I tried finding some Threads to link to, but the problems showed up under so many different titles that it was difficult to find much without scrutinizing all of the posts. These are a couple of tow harness problems:

Wierd issue with rear lights - Chevrolet Colorado & GMC Canyon Forum

Problem - Chevrolet Colorado & GMC Canyon Forum
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post #6 of 11 (permalink) Old 05-04-2016, 10:02 AM
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Any chance you can get a test truck or test trailer. A different trailer on your truck will prove your truck to be faulty, or clear it.
A test truck will do same in reverse.
How about a u-haul trailer as a test trailer?
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post #7 of 11 (permalink) Old 05-04-2016, 10:32 AM
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Originally Posted by jessb_55 View Post
Thanks so much for the responses. I am using a 4 prong plug. I'm starting to think that I have the OEM harness and that's why there is no ground wire to the frame. I'll look for corrosion, etc up at the front G105 ground pack. As for cleaning up the plug on the truck I did take a lot of contact cleaner, wire brush and dieletric grease to it as well, In fact several times last year f my memory serves me right I don't think I could get the trailer lights to work at times without dieletric grease. Like Vinolush mentioned this stuff can make a person crazy.... Last summer while on vacation I had my father in law hook up my boat to his truck and the lights worked fine....so I was starting to think it was definitely the truck especially cause there are many splice repairs between the converter and the trailer plug, but what throws me off is the fact that the ground light up my test light real well.

Cart7881 in terms of there being many issues with the OEM tow harness converter, can you elaborate some?

Vinolush, you mention some corrosion down there, which I agree but which area you referring to and would like me to clean up?

Thanks again!
As 08 and Cart say, check that ground that was identified. If no luck….

Hook up a test light as if it was a trailer using only the contacts on the trailer side of the plug. Then move the ground to the truck and check. The idea is to use different ground locations (plug and frame) at different times with the same wire.

Maybe then try that double ground.
That should let you know if the factory ground is at fault.

Better check the ground on the trailer as well in the same manner

I know, Ive had plenty of miserable moments searching for shorts, etc.

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post #8 of 11 (permalink) Old 05-04-2016, 12:59 PM Thread Starter
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Quote:
Originally Posted by Vinolush View Post
As 08 and Cart say, check that ground that was identified. If no luck….

Hook up a test light as if it was a trailer using only the contacts on the trailer side of the plug. Then move the ground to the truck and check. The idea is to use different ground locations (plug and frame) at different times with the same wire.

Maybe then try that double ground.
That should let you know if the factory ground is at fault.

Better check the ground on the trailer as well in the same manner

I know, Ive had plenty of miserable moments searching for shorts, etc.
So I worked on this a little bit more this morning, it seems I can get the lights to act up by wiggling the boat plug end. One time while the lights weren't working I took a wire and connected it to the frame of the truck and then to the frame of the boat and the lights kicked on. ( without having the trailer ball hooked up to the boat. I'm assuming this is telling me indeed that there is a ground issue.

I also doublechecked and didn't see any ground wires coming out of the harness by the logic box that were ground to the frame, so I'm assuming it is using the ground under the hood.I checked out the ground under the hood and cleaned it up some even though it looked good.


I was thinking shouldn't I be able to ohm out the ground plug on the truck to the frame and see that's no resistance, because unless I was doing it wrong I couldn't get that to be the case?

Next question is maybe my ground on the trailer isn't good, visually does this look like a bad place to ground it? (photo attached)

I did add some dielectric grease to the truck plug and it didn't seem to cut out as bad when I'd wiggle the plug end.

Unfortunately I don't have many friends near by that have vehicles with a hitch or have a trailer, I guess I'm a loser :(

I also doublechecked and didn't see any ground wires coming out of the harness by the logic box that were ground to the frame, so I'm assuming it is using the ground under the hood.

Vinolush I did hook up a test light to each connection on the truck and then grounded it to the frame, most of the time it would work but sometimes I'd really have to move the probe around, not sure if that again is a sign of the plug having an issue or that it's hard to find a good ground on the truck. As far as your comment "Hook up a test light as if it was a trailer using only the contacts on the trailer side of the plug. Then move the ground to the truck and check. The idea is to use different ground locations (plug and frame) at different times with the same wire.

Maybe then try that double ground.
That should let you know if the factory ground is at fault.

Better check the ground on the trailer as well in the same manner"

I'm not sure I follow, any chance you could elaborate a bit more on what you mean and how to do so?

Again, thanks to you all!
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post #9 of 11 (permalink) Old 05-04-2016, 03:12 PM
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I would not rule out the connector. If you wiggle the connector from the trailer and you get full contact, the contact points of the connector may be loose internally or corroded or anything else I don't know about (because I'm not really that smart).

If you can get a uhaul trailer, or similar, and the lights work fine then you can rule out the truck plug and truck system.

Or lastly, cut both plugs off and solder all connections. Then no matter where the poor connection is (unless trailer or truck frame ground) it will work perfectly. Kidding...do not really do that of course.
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post #10 of 11 (permalink) Old 05-04-2016, 04:50 PM
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Originally Posted by jessb_55 View Post
So I worked on this a little bit more this morning, it seems I can get the lights to act up by wiggling the boat plug end. One time while the lights weren't working I took a wire and connected it to the frame of the truck and then to the frame of the boat and the lights kicked on. ( without having the trailer ball hooked up to the boat. I'm assuming this is telling me indeed that there is a ground issue.

I also doublechecked and didn't see any ground wires coming out of the harness by the logic box that were ground to the frame, so I'm assuming it is using the ground under the hood.I checked out the ground under the hood and cleaned it up some even though it looked good.


I was thinking shouldn't I be able to ohm out the ground plug on the truck to the frame and see that's no resistance, because unless I was doing it wrong I couldn't get that to be the case?

Next question is maybe my ground on the trailer isn't good, visually does this look like a bad place to ground it? (photo attached)

I did add some dielectric grease to the truck plug and it didn't seem to cut out as bad when I'd wiggle the plug end.

Unfortunately I don't have many friends near by that have vehicles with a hitch or have a trailer, I guess I'm a loser :(

I also doublechecked and didn't see any ground wires coming out of the harness by the logic box that were ground to the frame, so I'm assuming it is using the ground under the hood.

Vinolush I did hook up a test light to each connection on the truck and then grounded it to the frame, most of the time it would work but sometimes I'd really have to move the probe around, not sure if that again is a sign of the plug having an issue or that it's hard to find a good ground on the truck. As far as your comment "Hook up a test light as if it was a trailer using only the contacts on the trailer side of the plug. Then move the ground to the truck and check. The idea is to use different ground locations (plug and frame) at different times with the same wire.

Maybe then try that double ground.
That should let you know if the factory ground is at fault.

Better check the ground on the trailer as well in the same manner"

I'm not sure I follow, any chance you could elaborate a bit more on what you mean and how to do so?

Again, thanks to you all!
Sounds like you're right there……

If you grounded directly from the truck to the boat trailer and all worked its probably your ground connection on the plug or the ground contact on the trailer or truck.

Check all your connections…

if no luck….

Try using a battery charger (any 12v source will do) and connect to the trailer plug as if it is the tow vehicle. You'll have to check one wire at a time.

The ground of the 12v source to the ground on the trailer plug. White should be the ground but always double check.

Connect The positive side of the 12v source to each contact on the trailer plug, brown (markers), yellow (drivers) and green (passenger). There maybe a black or blue if there's brakes or back-up lights.

wiggle during any of those wire contacts and see if you have problems. if you do take the 12v ground source and touch to a good ground spot on the trailer. good clean grounding is important.

you're just bypassing the truck and hooking directly to trailer. by process of elimination you'll determine if its the truck or trailer. Then you can concentrate on one of those….. but don't rule out both having connection problems. Again, tedious…..


If the problem stops it's probably the ground on the plug or trailer ground.

Hope this helps… hard to explain…

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post #11 of 11 (permalink) Old 05-05-2016, 05:51 PM Thread Starter
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Alrighty so last night I took the battery out of our boat and used jumper wires to hook it up to the trailer, ground to ground then each individual wire (green, yellow, brown) to the positive and everything worked great and no fiddling was needed, so I'm thinking it's more than likely the end on the truck, mainly the ground? Am I on the right track?

If so, any recommendations on what new harness to order, Brand?

Thanks

Last edited by jessb_55; 05-06-2016 at 03:08 PM. Reason: typo
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