Trailer Light Problem

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  #1  
Old 05-01-18, 04:37 PM
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Trailer Light Problem

I am sure this is the first post ever with trailer light issue. My 2000 Tracker trailer has an odd intermittent problem. I have LED lights and in normal headlights on mode, the left LED sometimes illuminates both the tail light and the brighter brake light. When in this failure condition, the turn signal will not flash on the trailer (OK on truck). As I said this is intermittent, sometimes it cures itself and works normally. No problems with the right side. No idea how to troubleshoot this. I have a flat four connector between trailer and 2002 Tundra.
 
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Old 05-01-18, 04:43 PM
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If that is a combination bulb unit (directional/parking)...... it's losing ground.
It could be the bulb socket or ground to that fixture.
 
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Old 05-02-18, 04:03 AM
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......or some bad wiring between the plug and the light.
A small plug-in trailer light tester is invaluable in ensuring problems are with the trailer and not the vehicle.

 
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Old 05-05-18, 08:33 AM
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Thanks

I've ordered an inline flat four tester. Out of town next week, but will trouble shoot the week after.
 
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Old 05-06-18, 06:54 PM
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Make Double sure you have a good ground, (probably a white wire) to a clean bolt or screw on the trailer frame. I have been pulling trailers for 40 years as part of my job, and unless you have a bad wire to the lights, or brakes, the ground is usually what causes intermittent problems.
 
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Old 05-17-18, 08:29 PM
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I got the flat four inline tester and of course since then the lights have worked perfectly. Mother Nature abhors boat trailers.
 
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Old 05-17-18, 11:29 PM
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No problems with the right side.
Since it only affects one side.... it's not the main ground to the trailer. It's the specific ground at one light fixture on the left side.
 
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Old 06-08-18, 08:14 AM
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Problem continues, but different

As a stated earlier, this worked fine for a few weeks, but yesterday the demons returned. In either right or left turn mode on truck, the right trailer light flashes. This is confirmed by the inline tester. Also no tail light power at flat four on truck. All truck lights work fine.

Should I just try a new trailer pigtail on truck? This is 2002 Tundra and this pigtail is a NAPA, about 8 yrs old. The original dealer supplied pigtail caused a bunch of electrical problems with the truck. The NAPA replacement has been good til now.

Any help appreciated.
 
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Old 06-09-18, 07:07 AM
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You are getting somewhere.
At least at the moment the tester shows a problem at the truck.

I would suggest that you begin inspecting the wiring at the connector itself then moving along the wire back to the front of the truck.
you would need to unwrap any tape or covering and look closely at the wires and connections, especially a ground connection to the truck..

Has the truck wiring been hacked or are the connections to a factory provided connector?
 
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Old 06-09-18, 08:30 AM
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The wiring has not been hacked. All connections into factory plugs. My flat four pigtail has a magic box in the middle with 4 wires out to the flat four and 6 wires in from the plug to the truck. The other side of the truck plug has 8 wires in. Logic tells me that since all lights on the truck are ok that I must have a problem inside the magic box. I have reworked the ground to the box with star washers and dialectric grease. No change. F,or under a hundred bucks at NAPA, maybe I'll just re plug and hope.
 
  #11  
Old 06-09-18, 01:23 PM
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If the lights on the truck work then it could be the 6 to 4 wire converter.
There could be a problem in wiring to the converter but it would be fairly easy to just try replacing the box rather than disturb any wiring or connections.
 
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Old 06-09-18, 01:35 PM
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Thanks, Greg. I have removed the whole pigtail from the truck and cannot get any continuity thru the 6 to 4 wire converter (Hoppy Circuit Guardian), other than the ground. No wires are visibly damaged, but I am estimating this NAPA part has been on my truck for 12-13 yrs, so it doesn't owe me much.
 
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Old 06-09-18, 03:28 PM
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Smile Thanks All

I think I have solved it. NAPA no longer carries my harness, but I found one @ Etrailer.
Then I remembered that the original Toyota harness was still installed behind my bumper. I plugged it in and the inline circuit tester shows everything good, so the failure must be in the Hopkins Circuit Protector. I abandoned the original harness in 2007 because I had intermittent dead batteries since buying the truck new. My independent Toyota shop said they had seen problems with the original harnesses and recommended the NAPA, which was great for 11yrs and no more dead batteries. Pretty boring thread, but maybe will help someone else sometime.
 
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