Trailer lights not working...lil help

(crracer) · (crracer) **Join Date: Nov 2003** 09-14-2006, 2:34 PM

Hey WWers,
Just hooked up the old truck to the boat for the first time in a while and i noticed i have no trailer lights except when i push on the brakes, i get a left brake light. Dont think its a fuse issue due to the one light however maybe the connection is bad, what should i clean the connections with
Thanks

(flux) · (flux) **Join Date: Jun 2003** 09-14-2006, 3:04 PM

Wire brush or some fine grit sand paper or emory cloth.

Take a look at the female plug (truck side). Sometimes those sockets are not tight enough. you can give them a bit of a pinch with a pliers and get them snug on the pins.

(rodmcinnis) · (rodmcinnis) **Join Date: Sep 2002** 09-14-2006, 3:42 PM

It could be a fuse.

On the trailer, left brake and left turn are the same light. The fact that you get left brake means the bulb and wires to the left light are okay.

If you get left brake but not left turn then there could be a problem on the truck. A lot of SUVs and trucks that came with a "tow package" have a set of relays and fuses specifically for the trailer and it is possible to blow one of those fuses. Truck lights work okay but trailer lights don't.

Before you do anything, however, the first thing I would do is check the ground connection between the truck and trailer. If you don't have a good ground the lights can get screwy.

Does the trailer light connector have a specific ground wire, or does it rely on the hitch for ground? If you have the common four/five pin flat rubber connector then the ground wire it the one odd connector and should have a white wire associated with it.

If you don't have a ground wire then I would add one! Old rusty hitches and/or receivers are notorious for making a bad ground. If you are not sure of the ground grab a pair of jumper cables and connect from truck to trailer frame and try the lights again.

The next thing you should do is test the lights at the truck connector. You can use a voltmeter but a test light is easier. Clip the ground lead to the odd pin (which will be the bare connector on the truck side). Turn the head lights on, test to the next pin over. Turn the left turn signal on, test the second connection over. Turn the right turn signal on, test the 3rd (last) connection.

Here is a good website for a wiring diagram:
http://www.championtrailers.com/4%20pole%20wiring%20dia.pdf

If you don't have power at the connector then check the truck wiring and fuses.

If you have power at the connector, and you have good ground to the trailer, the it is either the trailer wiring, a burnt out bulb or the light fixture has gotten flakey.

(lmtwa) · (lmtwa) **Join Date: May 2001** 09-14-2006, 3:43 PM

Bad grounds are a major source of light (trailer)) problems. Make sure there is a good ground - if the ground is attached to the trailer with a screw - loosen it - clean the connection and retighten....also - first check all light bulbs (trailer side) for continuity (VOM meter - if you have one) - otherwise you end up chasing problems with a bad bulb. If you don't have a Volt meter - swap bulbs into a good socket.Also use the VOM to check voltage at the trailer connection (from the car side) to see if you are getting voltage in each. Good luck/.
PS I am assuming your tailights on the truck are working correctly.. If so - I think that rules out any fuses problem.

(lmtwa) · (lmtwa) **Join Date: May 2001** 09-14-2006, 3:46 PM

Sorry Rod
I didn't see (for some reason) your response until after I posted - you pretty much covered it.
Also - I assumed that his truck lights were OK - just the trailer was a problem.

(crracer) · (crracer) **Join Date: Nov 2003** 09-14-2006, 5:32 PM

Thanks
you guys rock

(7890303) · (7890303) **Join Date: Sep 2006** 09-17-2006, 10:40 AM

if your all of your truck lights work, the problem is more likely on the trailer. If the trailer wiring & connector has been cut spliced several times, I suggest going to Napa Auto parts & buying 30' of 4 trailer light wiring harness. rip all the old stuff out & re wire to new lites. This can be done in less than an hour. buy a test light at the same time, the 4 wire harness can be used for left, right, brake & ground. use test light to I.D. wiring from truck, ie blinkers, turn signals, etc. for as much time & money as most people put into their stereos, this can done & worry free for less than $75. & in about 1 hour. voltmeters test how much power is coming in, test lights just tell if there is power, & thats usually all you need.
If your stil having problems take it to your local auto repair facility, like Duncans Automotive in Roseville CA. feel free to call me at the shop 916-789-0303, ask for Marc