Towing Harness, bad ground? -
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Unread 06-01-2009, 07:01 PM   #1
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1999 TJ Wrangler 
Join Date: Jul 2008
Location: BC, Canada, eh?
Posts: 181
Towing Harness, bad ground?

I attached my wiring harness to my tail lights and then to my trailer. During my light check, I noticed the brake lights on my trailer were more dim than usual. also, it seems my blinkers were reversed. Left on the steering column resulted in right on the trailer and vice versa. I thought I may have had the wiring harness reversed but that wasn't the case. Could there possibly be a bad ground somewhere in my tail lights on my 99 TJ? I have used the trailer with a different vehicle recently and did not experience any of the above mentioned. I have yet to try a different harness as well.

Any ideas as where to begin the search?

Thank you for your time and I appreciate the assistance.


funky_boss23 is offline   Reply With Quote Quick reply to this message
Unread 06-01-2009, 07:47 PM   #2
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1998 XJ Cherokee 
Join Date: Oct 2007
Location: portland
Posts: 166
a bad ground could definitely cause dim lights but the reversed blinkers still doesnt make sense because they are different wires and there is no way a ground could flip them around. I would definitely try a different harness, it sounds like some of your pins may be out of order.
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Unread 06-05-2009, 05:37 AM   #3
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2006 LJ Wrangler 
Join Date: May 2009
Location: SE Michigan
Posts: 1,559
sounds like either your tailight harness or your trailer is wired backwards. if the trailer works correctly on other vehicles, you need to flip the R/L wires on the tj to make it work with your trailer. R/L is a wiring issue, not ground issue. dim lights=poor ground, weak signal

make sure the ground wire on the tj side and the trailer side are good/clean/tight. also, make sure theres not alot of surface rust/grease on your trailer ball and cupler. the ground on the harness is usually in most cases is just a secondary and the trailer is actually primarily grounded through the ball to the vehicle. the white wire supplies a constant ground so that your lights dont flash when you hit a bump and the coupler rattles, or if your ball doesnt make good connection.

on a 4 way flat harness:
yellow-left side blinker/brake
green-right side blinker/brake
brown-running lights

hope this helps. if you need more info just ask.
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