Trailer Wiring

Tiny
HMAC300
  • EXPERT
See pic red is hot wire and make sure you have a good ground. Yellow is lh t/s and dk green rh t/s brown is tailights
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Monday, May 22nd, 2017 AT 12:30 PM (Merged)
Tiny
DAVIDSLUSHERMCGMAILCOM
  • MEMBER
The diagram says W/O crew cab. Mine is a crew cab. Does it make a difference? Thanks
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Monday, May 22nd, 2017 AT 12:30 PM (Merged)
Tiny
HMAC300
  • EXPERT
Is it a 2500 or 3500 you didn't say. Besides that is only the ground that they are talking about not the connector
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Monday, May 22nd, 2017 AT 12:30 PM (Merged)
Tiny
DAVIDSLUSHERMCGMAILCOM
  • MEMBER
Sorry, it's a 2500hd Duramax. Thanks
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Monday, May 22nd, 2017 AT 12:30 PM (Merged)
Tiny
THOMAS2323
  • MEMBER
  • 1999 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 216,490 MILES
Electrical problem
1999 Chevy Silverado V8 Two Wheel Drive Automatic 216490 miles

I hook my trailer up to my truck and plug in the lights. I check the lights to make sure they work, check the blinkers, brake lights and tail lights and they all work correctly. Here is where the problem starts, when I hit my brakes or turn my lights on and hit my blinkers, the lights on my trailer flash like lights at a rail road crossing.
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Monday, May 22nd, 2017 AT 12:30 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
First, I have to tell you, I laughed when I read your description. The RR crossing lights got to me.

Explaine this. Do they flash left, right, left. Or do they all seem to go haywire? Also, you mentioned first you checked them and they all work. Do you have to turn the key on or something for this to happen or does it do it all the time? Finally, are you sure the wiring on the trailer is good? Have you checked the plug on the truck to make sure everything is working properly using a test light? To be honest, it sounds like either you have a bad trailer ground or mice may have gotten into the wiring.

Let me know.
Joe
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Monday, May 22nd, 2017 AT 12:30 PM (Merged)
Tiny
THOMAS2323
  • MEMBER
Yes, this happens when the key is turned on. When doing a basic check of the lights, the left blinker works, the right blinker works and the brake lights work, it is only when I turn on the lights or hit the brake and then check the blinkers that they flash left, right left, right. I completely traced the wires on the trailer and all is well. I checked the plug on the truck and it checks out as well. I'm about ready to pull my hair out.
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Monday, May 22nd, 2017 AT 12:30 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Don't pull your hair out. I know it is frustrating. Have you tried running a seperate ground wire from the trailer to the battery itself in the truck? I still think it is a ground problem.
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Monday, May 22nd, 2017 AT 12:30 PM (Merged)
Tiny
THOMAS2323
  • MEMBER
O.K. So before I run a seperate ground I take another look at my wireing harness just to make sure everything checks out, when my wife yells at me telling me that they just started working. So my guess would be in the harness some where. Now my nest question is when I jiggled the wireing harness and the lights started working why would my plug so to be working properly before I Jiggled the harness. I hope you understand the question.
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Monday, May 22nd, 2017 AT 12:30 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
I wish I could meet you. You sound just like me and my wife. (LOL)

If that is the case, either you have a short in the wiring itself, or there is a ground that is now making a better connection.

I know if sounds crazy, but a weak ground will do strange things. I have an old Hi Lo that I refuse to pull any more. The last time I worked on it, when I put on the brakes, the lights inside the camper would turn on. Believe it or not, it was a bad ground that caused me to loose more hair than I had to loose. That is why I am pushing you in that direction.

Check it out and let me know if it helps.

Joe
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Monday, May 22nd, 2017 AT 12:30 PM (Merged)
Tiny
THOMAS2323
  • MEMBER
I checked the ground, and it looked good but to make sure I disconnected it sanded the area on the frame to make sure of a good ground and re grounded it. Every thing is still working, so it has to be in the wireing harness somewhere I would think. P.S. Just like you said.
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Monday, May 22nd, 2017 AT 12:30 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
They are a pain. Chances are there is a wire that has the insulation worn through and is shorting. Last year I went nuts with mine. Like I said, when I hit the brakes, the lights inside the trailer turned on. You should have seen that at night. It was like someone was living in there as I drove them around.
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Monday, May 22nd, 2017 AT 12:30 PM (Merged)
Tiny
ZOLI
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • 4WD
  • 313,000 MILES
Randy,

I have the exact same problem with the right turn signal on my trailers. I have 2 trailers and they both do the same thing. In addition hooked up a differnt truck and the lights worked fine. Got ripped off by a trailer place in Salinas, CA ($190.00) bucks worth of BS Left turn blinks just find. Right turn blinks emergency on the trailer but right turn on the truck. Replaced the truck plug in with a new one. Did you ever figure out what was causing your problem. Z.
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Monday, May 22nd, 2017 AT 12:30 PM (Merged)
Tiny
HMAC300
  • EXPERT
Check ground from trailer to truck
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Monday, May 22nd, 2017 AT 12:30 PM (Merged)
Tiny
JOHN16115
  • MEMBER
  • 2005 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 37,700 MILES
Electrical problem
2005 Chevy Silverado V8 Four Wheel Drive Automatic 37700 miles

I keep blowing my trailer fuse when I connect my seven plug connector from my small horse trailer to the truck. I have checked all the lights and grounding on the trailer. The lights work fine off a battery, however, when I connect the trailer cable with the truck running, the fuse will blow. If I connect with the truck off, it will work for 5 minutes and then blow. I'm not sure if I can increase the fuse size or not. I have a utility trailer with a four plug connector that works fine. The hitch is a GM hitch with the prewired cabling.
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Monday, May 22nd, 2017 AT 12:30 PM (Merged)
Tiny
DJENSEN7
  • MEMBER
  • 2003 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 154,000 MILES
Electrical problem
2003 Chevy Silverado V8 Two Wheel Drive Automatic 154000 miles

Does the 2003 Silverado have a snap in trailer light harness or do I have to splice into the taillight wiring?

What about trailer brake wiring?
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Monday, May 22nd, 2017 AT 12:30 PM (Merged)
Tiny
DENNYP
  • EXPERT
You should be able to purchase a quick connect trailer harness kit for it.
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Monday, May 22nd, 2017 AT 12:30 PM (Merged)
Tiny
DENNYP
  • EXPERT
Sounds like the problem is with the trailer. Make sure all of your connections in the trailer wiring are good clean connections.
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Monday, May 22nd, 2017 AT 12:30 PM (Merged)
Tiny
ZOLI
  • MEMBER
Ok

As I wrote, I had a new plu put on the trailer and the problem is still occurring with two differnt trailers. But when I hooked up a differnt truck everything was ok . So now I just have to find the ground. I always heard that 90% of electrical problems are bad gounds.
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Monday, May 22nd, 2017 AT 12:30 PM (Merged)
Tiny
CKHS
  • MEMBER
  • 2004 CHEVROLET SILVERADO
I have a 2004.5 Chevy Silverado crew cab 4x4 with the duramax diesel and the alison trans with 29,995 miles on it. I just started having problems with the factory trailer wiring circut. When I step on the brakes I only get the right brake, and when I turn on the right blinker, I get power to both right and left blinker. This test was done with the trailer hooked up and also without being hooked up using a test light. This problem is at the rear on the factory 7 wire plug and at the fithwheel wire assimbly between the cab and the bed.

Any ideas? Chevy said maybe a bad relay under the hood but which one? It's not marked for trailer on any of the relays under hood, only fuses which are all good. This truck does not go off road and is very clean.

Thanks,
Corby
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Monday, May 22nd, 2017 AT 12:30 PM (Merged)

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