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View Full Version : Trailer lights won't work


Jim1982
03-04-2012, 06:11 PM
I have a 1998 Jeep Grand Cherokee. I recently had a hitch installed and want to pull my boat. When I hooked my trailer up the lights worked. But when I turned the car head lights on nothing works. I have no clue what the problem is. Any suggestions?

Stutsman230
03-04-2012, 06:27 PM
Do the trailer lights work when the headlights are turned back off? I have found that when trailer lights go off and on with different combinations of car light switches it's always a problem with poor grounding. Check to see where the they have connected the ground wires on the car as well as on the trailer. Some hitch installation places think that the ground will work through the hitch ball!

mikeg205
03-04-2012, 07:08 PM
+1 on the towing vehicle ground. My installer clipped the ground to a corroded screw...poos connection....Make all the ground on the vehicle side is good. Get a voltmeter... and check the connections.

Good way to isolate towing vehicle or trailer issue.

Jim1982
03-05-2012, 06:37 PM
I have a 1998 Jeep Grand Cherokee. I recently had a hitch installed and want to pull my boat. When I hooked my trailer up the lights worked. But when I turned the car head lights on nothing works. I have no clue what the problem is. Any suggestions?

As soon as I turn the headlights back off the lights on the trailer work again.

ctjahn
03-05-2012, 06:48 PM
Try hotwiring the ground to the trailer off a light and/or off the hitch... (just an idea). Or test it by connecting the trailer wiring to the +/- to be sure (educated guess). Put the white on the ground of a battery, then then try the yellow, green, and brown....

OR; get one of those cheap inline wiring testers from the auto parts place that shows the LEDs... inline and you can use that to test. OR a "driver" with a light bulb on the vehicle harness...

Its worth a shot.

Cj

thatsmrmastercraft
03-05-2012, 08:28 PM
Strange trailer light issues are almost always related to a bad ground. Start by ensuring the trailer wiring on the tow vehicle is working properly with a cheap tester ($5 at West Marine and lots of other places). Next step would be to check the trailer ground wire on the trailer tongue. Grounds can be faulty even when they look perfectly fine. Usually worth cutting the wire end and crimping on a new connector and replacing the screw going into the tongue.

While you are at it, I would clean both battery connections as well as the ground connection at the block on your truck.

mayo93prostar
03-05-2012, 08:44 PM
take it back to the hitch place and make them fix it.