Electrical issue and trailer plug socket removal

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Joined
Feb 23, 2009
Threads
4
Messages
19
Location
North Van, BC
Intro, electrical issue and trailer plug socket removal

Hello all,

Been roaming around this forum for a few months now. Its been a great source of knowledge, thank you. Purchased my LC a few months ago in CO and had the boys at Slee do a once over as well as a suspension and loadbar install. Had an 01 Tacoma for a few years before this.

The LC has been on many mountain biking and camping adventures around BC, WA and OR with me already and am looking forward to driving it around in the snow this winter.

Trying to bridge the gap between off-road ability and road-trip worthiness. Keeping the weight low is important to me, as well as making sure that all mods are made for a purpose. Its hard to stay focused on what I really need when seeing all the beautifully modded trucks on here!


Now for the problem:

I removed the stock trailer hitch to install the toyota cross member integrated bumper hitch assembly. Was lucky that my 03 with tow package came with cross member insert already. Allows for much better rack clearance back there.

In the process I removed the 7 pin trailer plug socket from the truck by just un-plugging it at the first connector up from the plug itself. I did not think this would be a problem, and was planning on finding a nice rubber sealing plug for the open end down there.

About 24hrs later, as I was driving home, a very loud intermittent "incoming fax" sound came from below/behind the dash. Limped home (under a 1 km) and minutes before pulling into the parking the ABS, VSC, TRAC and handbrake light went on accompanied by a loud steady alarm beeeeeeep.

Restarted the truck a couple of hours later and the "fax sound" was gone, but the alarm and dash lights were still on.

Symptoms sound very much like the ones described in this thread: https://forum.ih8mud.com/100-series-cruisers/150705-urgent-help.html#post2088441 of the FAQ.


I did not think removing the trailer harness would cause an issue? Did lots of reading on here and found info on how to install a trailer plug, but not on the procedure to remove it. I do not see how this would cause a short?

According to the past link the problem could be that: " The buzzy sound was the main junction box for the main wiring harness, and that the Juction box shorted out and is tripping the warning system buzzer." Could this have simply been caused by removing the plug?

Now, silly question, could I plug the trailer socket plug back into its connector and reset the ECU (pull battery terminal for a few mins) and solve the problem? Or did I do permanent damage to the main junction box and have to replace the whole thing?

Going to take the truck to the dealership on Monday but want to try and understand the problem with you guy's help here first. I have not had good luck communicating with the local toyota dealership in the past.

Thank you for insights or comments!

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It could just be the the junction box problem.

OTOH the Toyota trailer wiring converters are notorious for imploding and since everything is connected it could be converter box issue.

Unfortunately it's likely the previous owner tore out the Toyota box after it failed or maybe the second time it failed. These boxes were designed to protect the vehicle's main electronics from trailer wiring shorts/spikes ect... and apparently usually die trying. They are often replaced by cheap aftermarket converters that provide no protection but only convert the signals for the lights.

Start by inspecting the converter. See if it's a Toyota or Aftermarket unit. It's glued inside the left rear quarter panel behind the bottle jack storage. A literal black box. Check the output wires to see if it's working. If any of the outputs aren't working take it out and install an aftermarket converter. The best kind is an independently power "isolated" system that will protect your trucks electronics.

A list of Trailer wiring threads is at the end of this post.
https://forum.ih8mud.com/100-series-cruisers/225174-2000-trailer-wiring-questions-advise.html

6gun's Isolated Converter Install

Nice truck too!
 
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Thank you for your help.

I checked the converter behind the bottle jack and it is a toyota.

I am not knowledgeable with electronics: how do you check if the output wires are working ?

From what I understand, if the converter is not working properly, it would have allowed damage to the junction box (?)

Could just removing the socket plug really be the cause of this or could it just be a coincidence (i know unlikely!) ?

If so, what do those with aftermarket bumpers do with the trailer plug socket?

Do you guys think I can create more damage by driving it with the ABS, TRAC, VSC OFF and handbrake dash lights on and with the buzzer ringing , about 1 mile to the dealership?

BTW, it is an amazing vehicle. Miles smoother off-road than any other truck i have owned. Nice when you spend alot of your driving on washboard roads.
 
You need to pull the codes to really know what's going on. If the truck is driving well I think a short drive to a service bay is no danger.

I still think the trailer plug and this problem may be unconnected. Have you check to make sure that the windshield is well installed. Other junction box problems have been caused by improper installation of a replacement and a leak behind the firewall.

The Toyota Converter box should have protected the electronics upstream. The failures have generally only resulted in trailer light problems and nothing else.

To check the output you could just plug the harness back in and put a test light on the plug checking the signals (right tail light. left tail light ect...). I'd pull the codes first.
 
A quick update:

I plugged the trailer hitch socket plug back in and drove to the dealership to drop it off. After under one mile of driving the ABS, VSC, VSC OFF and handbrake light went off and the loud continuous alarm sound stopped. The truck drove perfectly normally (as it always did, despite everything else) the rest of the way (about another half a mile). All electric accessories and functions seemed to be working as normal.

I'm wondering if the dealership will be able to pull a code...?
Will post up when I hear back from them.

UPDATE:

Picked the truck up from the dealership. No codes came up and none were in memory.
Before I use the trailer wiring socket next, I'll update the converter to an independently powered "isolated" system. In the meantime I'll keep the socket plug connected and find a tidy spot for it to live under the truck. I'll make a bracket so that it's secure and sits under the bumper line.
 
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