Left Blinker on Trailer works when Right or Left on Truck is on!

[Scuda11]

Hi all, I am puzzled. I did some searching to try and find a solution to my dim trailer lights and found this:

[FONT=&quot]To check the trailer use a battery charger. Connect the negative lead to the trailer frame. Touch each of the other three terminals and the appropriate light should turn on. Turn signals obviously won't blink because there is no flasher but it proves the circuit is good. [/FONT]

I did that test the best I could by myself (put a nail in the light and connected it to my pos on the charger so it would stay put) and I had NOTHING on either light. So I went back to looking for a ground problem.

Not seeing my white ground under the bumper going to anything, I went uder the hood of my truck (99 Chevy Silverado) I found the green ground wire (master maybe?-pic attached) and it did appear a bit loose. Tightened it up a bit just with my hand and when I tried my lights again, the left blinker on the trailer works when EITHER right or left blinker on the truck is on!!!

Any ideas? Thanks in advance.

 

[Silvertip]

Re: Left Blinker on Trailer works when Right or Left on Truck is on!

You probably have a bad gound on the trailer -- and/or the truck. Why is the ground wire run all the way to the front of the truck anyway? The battery charger test is very valid. But the trailer and truck still need a good ground on the white wire in the connectors. Otherwise the hitch becomes the ground and that's not a very good one.

 

[Scuda11]

Re: Left Blinker on Trailer works when Right or Left on Truck is on!

You probably have a bad gound on the trailer -- and/or the truck. Why is the ground wire run all the way to the front of the truck anyway? The battery charger test is very valid. But the trailer and truck still need a good ground on the white wire in the connectors. Otherwise the hitch becomes the ground and that's not a very good one.

Thanks Silvertip. I looked under the bumper and from the trailer light wires forward (I uncovered the black wire casing) I could not see the white step out of that anywhere.

I did the test without the trailer hooked up to the truck but I grounded the neg clip to my trailer, did I do it wrong?

Another question: If I take off the ground in the front of my truck (in the other picture) do I need to disconnect my batteries first?

Thanks again.

 

[tashasdaddy]

Re: Left Blinker on Trailer works when Right or Left on Truck is on!

scuda, many years ago i stopped having trailer light problems, by not relying on the trailer frame for the ground. i always run a ground wire around my trailer, and attach it to every fixtures mounting bolts, then to the white wire on the harness. this solved all my problems except blown bulbs. here a good link: http://www.easternmarine.com/em_store/tech_info/light_tech.html

 

[Silvertip]

Re: Left Blinker on Trailer works when Right or Left on Truck is on!

You did right to connect the ground clip to the trailer frame. But remember, if its painted, you don't get a good connection. If you don't have a white wire in the truck end of the trailer connector you need to fix that. Ground - Ground - Ground. Got to have it.

 

[BrianS.]

Re: Left Blinker on Trailer works when Right or Left on Truck is on!

Place a meter or connector light indicator at your truck connection and first see if the problem is there.

 

[burroak]

Re: Left Blinker on Trailer works when Right or Left on Truck is on!

If you have a tilt trailer, the pivot can be the culprit. A solid ground connection from the tongue to the A-frames will solve much of the errant electrical problems.

I suppose you could run 14-2 w/ground in Romex. But, why? If your grounding points are clean and covered with liquid electrical tape when done, you should have no problem. I have never seen a 14 gauge trailer wire that could carry as much current as a 2 1/2" X 4" iron C-channel.

 

[Scuda11]

Re: Left Blinker on Trailer works when Right or Left on Truck is on!

Thanks guys. What should i be getting for voltage coming out of my truck, should it be 12 or near 12 volts on each blinker?

 

[BrianS.]

Re: Left Blinker on Trailer works when Right or Left on Truck is on!

What you are really looking for is the signal. Make sure is coming out of only 1 connector for Left, then the other for Right, then one for Running Lights.

Thanks guys. What should i be getting for voltage coming out of my truck, should it be 12 or near 12 volts on each blinker?

 

[kwikrnu]

Re: Left Blinker on Trailer works when Right or Left on Truck is on!

You know the ground is working if the lights are bright on the trailer. If they are dim or not working or even intermittant there could be a ground problem.

Are you using the factory trailer light connections? Behind the spare tire (towards front of truck along the bed support) there is a wire loom which contain ground, power, brake, blinker and runnin light wires. The chevy has both amber and red rear lights so seperate wires for the brake and blinker.

Good luck.

 

[dad's boat]

Re: Left Blinker on Trailer works when Right or Left on Truck is on!

Just an idea
I had to get this isolator box thing (can't remeber offical term right now) from napa auto parts, but that was for a toyota. mine was doing the same thing tell I instaled that box.

 

[azlakes]

Re: Left Blinker on Trailer works when Right or Left on Truck is on!

I had something similar. After some testing and skull scratching, found that the trailer light bulb had been twisted inplace to far and making to much contact causing a short when the signal lights were applied. Try reinstalling the bulbs carefully and see if anything changes.

 

[freddyray21]

Re: Left Blinker on Trailer works when Right or Left on Truck is on!

provided the sockets at the trailer have a good ground you can check the trailer lights and the harness using the battery charger. Hook the ground to the white wire. Then each in turn hook the + to each wire. I think brown is common for tail and brake lights. I can never remember if green or yellow is the left of right, but if you run voltage one at a time to them only the left or the right should come on not both. If both come on you have a wire crossed somewhere. Doing the test not hooked to the vehicle tells you if the trailer is wired right. If you hook it up to the vehicle you can't tell if the problem is in the trailer or the vehicle. Once you have determined the trailer is right hook it to the vehicle if you have a problem then it's in the vehicle wiring. Some cars with the separate bulb for the turn signal will need an adaptor when wiring new lights. Factory trailer wiring already has this built in, but they do go bad.

 

[tymtogo69]

Re: Left Blinker on Trailer works when Right or Left on Truck is on!

Brown is parking,yellow is left turn and brake,green is rigt turn and brake. You do not need a converter for your truck as the factory installed trailer wiring harness is on it's own seperate circuit and is not at all tied into the vehicle light circuit.Also 99% of all trailer wiring problems can eventually be traced to a bad ground.

 

[Bt Doctur]

Re: Left Blinker on Trailer works when Right or Left on Truck is on!

re-read # 4 again.
Had similiar issues until i ran a sep. ground for each light.the stud that uses the ground to the frame on the light may be bad.

 

[freddyray21]

Re: Left Blinker on Trailer works when Right or Left on Truck is on!

Brown is parking,yellow is left turn and brake,green is rigt turn and brake. You do not need a converter for your truck as the factory installed trailer wiring harness is on it's own seperate circuit and is not at all tied into the vehicle light circuit.Also 99% of all trailer wiring problems can eventually be traced to a bad ground.

from his pic I would not say that is a factory installed wiring harness.

 

[Silvertip]

Re: Left Blinker on Trailer works when Right or Left on Truck is on!

Remove the bulbs and take a careful look at the two nubs on each side of the bulb. You will see that they are not in-line with each other. That's to prevent the bulb from being inserted in only one way. However, many a persons simply stick the bulb in and force it in the wrong orientation. The sockets are made so sloppy that they can actually insert the bulb wrong. That can cause some real weird light responses.

 

[Scuda11]

Re: Left Blinker on Trailer works when Right or Left on Truck is on!

Hello everyone, I am trying to finally fix my ground problem (boats been in the water). I was thinking I would just cut the ground wire on my truck off of the connector and ground it myself to the truck bed. Can you tell me again which one is my ground? I know stupid question, but I forgot, is it the green one or the white one in this picture.

Thanks again.

 

[Scuda11]

Re: Left Blinker on Trailer works when Right or Left on Truck is on!

Ok, a little update. I tried some stuff when it was dark. Again, left blinker works fine. When right blinker is on, left blinker goes off (just as bright) and the right blinker is going off too, but REAL dim.

 

[wire2]

Re: Left Blinker on Trailer works when Right or Left on Truck is on!

White is the ground in your plug in the pic.

http://www.accessconnect.com/trailer_wiring_diagram.htm

I have no idea what that under hood green wire in an earlier pic is, but I don't think it's anything to do with your trailer wiring. It's not factory, someone has added something.