Help with trailer wiring

Joined
Sep 20, 2014
Messages
2,452
Location
Seattle-ish, WA
I have not used the trailer connector/towed with my truck in quite a few years. The other day I went to use it and the trailer lights did not operate properly. I verified the trailer was a-ok by plugging another vehicle into it. I cleaned my connector thoroughly with solvent and a bore brush so the connection is sound.

The problem is I do not have, and cannot locate, a factory wiring diagram to positively decipher the factory wiring harness - it has a five wire connector installed and goes through a typical 3-2 adapter to give the 4-way flat wire output. This was wired in when I got it and "I think" it worked properly but I can't be 100% sure.

IMG-3713.jpg


Here is how it is working now:

brake lights: only right, no left
Turn signals: only left, no right
tail lights: OK
Turn signals w/tail lights on: both work correctly

I am wondering if there is a way the wires could be mis-wired to create this, or it's a fault in the adapter. I am thinking it must be the adapter. I checked all connections and they were good; I tried swapping some wires w/o any improvement (brake for R. turn, l. turn and R.turn, etc.) Without the wiring diagram I'm stuck. I can get another adapter but don't know if it will work, either. Since it's the stop/turn functions, which is what the adapter modifies, I can't be sure if it's the input or the circuitry inside.

The truck is a 1998 Acura SLX, which is a 1998 Trooper re-badged. I've looked online and also asked at planetisuzoo and searched back 15+ years of threads with no success in finding a wiring diagram for this.


Thanks!
 
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Joined
Apr 9, 2008
Messages
15,046
Location
Central NY
My vote is on fault in the adapter. Those things go bad all the time. I had one in my Cherokee that was doing all sorts of weird things. Hooked the trailer up to another friend's cherokee and it did the same thing. After I rewired the trailer it still didn't work right. Turns out the adapter boxes in both of ours went bad.
 
Joined
Nov 9, 2008
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18,647
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NH
Sure sounds broken to me. The blinking should be controlled by the vehicle's blinker; I believe this box, where it has no power in it, is nothing but some steering diodes.

I would check where it goes into your vehicle's wiring, likely it plugs into or taps the bulbs next to the housing. Just to verify. But I vote broken. I had one of those units and it took nothing to break it seemed.
 

Oro_O

Thread starter
Joined
Sep 20, 2014
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Seattle-ish, WA
OK, good advice. That helps me know these are less reliable than I imagined.

Other vehicles I have wired I wired in directly myself, haven't used one of these before and I did not wire this one up. I did not know these were so fragile. It's 10+ years old so I'll order a direct-plug Curt one - Autozone had them for $24, so that's pretty reasonable IMO.
 
Joined
Mar 21, 2004
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26,382
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Upstate NY
Those blue connectors suck. They make it easy but are trouble prone that day after they are installed. Is there a adapter made for your specific vehicle that plugs into something or goes between two ends of an existing connector? Do you have a DVM? You need one and know how to use it.

Lastly bad ground is always a good possibility with trailer wiring.
 
Joined
Sep 7, 2011
Messages
67
Location
CA
Use a 12V test light and poke the wires near that adapter to see if you have power on the lines when you should. It could be your adapter, it could be those wire taps not making a good connection. A test light should help you to figure out why your lights are not working correctly. Don't forget to check the ground wires as well.
 
Joined
Jan 25, 2008
Messages
4,452
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Guilford, CT
Use a 12V test light and poke the wires near that adapter to see if you have power on the lines when you should. It could be your adapter, it could be those wire taps not making a good connection. A test light should help you to figure out why your lights are not working correctly. Don't forget to check the ground wires as well.
^^This! I was about to say the same thing. A test light will verify that you're hooked up to the correct wires, and will verify that the vehicle wiring is good and functioning. Then use the test light to test the output of the adapter. If the wiring on the vehicle-side of the adapter works, but the trailer-side of the adapter doesn't work, then the problem is definitely a bad adapter. And I agree that you should lose the Scotch-locks! Crimp or solder and heat shrink only!
 
Joined
Nov 9, 2008
Messages
18,647
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NH
So... I cobbled together my own convertor this past weekend for my newer car, as my old Camry has a very similar looking, non-powered convertor. Wow! I did not know the trailer lights could be so bright. My homebrew convertor uses auto relays and a direct battery feed for power, wire is undersized but it doesn't matter, the lights are now ON. I was going to convert to LED lights but now maybe I don't need to.

Anyhow. If the right wires are tapped then I wonder if a new convertor is recommended, and in which case, I'd get one with a power wire on it.
 
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