Problems With Trailer Hook Up On 02 Explorer

[JacobMHD]

I originally posted this in the trailer wiring post but felt more poeple would find it here. I did read through the trailer wiring post.

I have an '02 Explorer that is causing me some problems. The trailer light hook up has only worked once since I purchased it and I think the weather had something to do with it. The roads were really wet and it was raining. Any other time I have hooked up a trailer there is nothing there. I think I have checked the correct fuses, according to the owners manual anyway. They were fine. I did check the plug for power at all four terminals with the lights on and the flashers going. No power to the plug. I followed the wires to a connector tucked up in the back bumper on the passenger side and checked the connector terminals there as well. No power to these either. Because the lights worked during an early spring rain storm I am thinking that it may be a ground?? Any suggestions are greatly appreciated. I can take pictures if that makes it easier for the experts.

[Brad B]

where the wires go up to the connector in the bumper can this connector be unplugged. I am asking because if you explorer is like most newer vechile the wires you plug your trailer into is a complete harness assembly. I was thinking you might want to try and unplug the harness and hook the wires back together where your trailer harness was. now if you don't have power going to the harness then you may have a bigger issue someplace else in the wiring. I would imagine your lights on the vechile are not working in the back either. if you put the wires together that are going into the harness and the lights on your vechile work then I would say maybe you have a faulty trailer wiring harness. A new wiring harness is not to expensive may $25.00 so I would replace that.

[BobT]

This may seem like a condescending question but I have experienced this too often not to ask so please don't misunderstand. What did you use for a reference when you tested for voltage? An automobile doesn't really have a ground as it is actually insulated from ground by the tires but we often use that term as you did and so that's what I'm referring to.

One of the most common solutions to trailer wiring that I have encountered is a poor or inadequate dc common connection back to the battery, which in most vehicles would be the negative (-) connection. It's amazing how many times I find there is no wire connection through the plug to the trailer frame because it is either broken or not used at all. Instead, the contact between the trailer tongue and the ball is relied on to make this connection. This is a poor connection because it moves too much. Somthing to consider.

[Shack]

Quote:

This may seem like a condescending question but

Yep Bob It did lol!

These guys pretty much covered the basics for ya.

[JacobMHD]

Brad B:

When the connector was removed the lights on the back of the vehicle still worked. I stuck the tester in the terminals with no results. I tried each one twice just to make sure I was seeing things right.

BobT:

No problems, I will safely assume you meant no harm. I used an extra ? to show I was unsure. I thought maybe, and I could be very wrong, that the extra moisture on the "ground" connection made the lights work. I clipped the tester to the frame.

Since the trailer wasn't even hooked up when I was testing for power in the lines, what should I look for? I

[Brad B]

my next suggestion would be to take the connection apart and check each terminal with a tester by bridging across the conection with a tester that will check for a complete curicut. if you don't get a complete curicut then you most likely have a broken or loose wire some place else on the vechile.

[JacobMHD]

I'll give it a shot tonight and update in the morning.

[BobT]

I meant no anymosity. I remember when I was going to school for electrical design an instructor told us about his experiences as a television repairman. Yes, that ages me a bit. He told about how common it was to receive a phone call, travel out to the home, only to find out all he had to do was plug in the television! He then began doing similar to what I just did and before accepting the service call he would ask the customer to check to be sure it was plugged in. He lost about 10-20% of his business but he gained a lot of respect from his customers and in the end gained more business than he initially lost when he changed his policies.

I experience similar situations in my current position. I've received calls from customers trying to troubleshoot Programmable Logic Controllers and I have learned to ask them if the processor was in run mode. You'd be surprised how often I've saved a field service call that would have cost them a few thousand dollars for someone to go on site and turn a key on the front of the processor.

[walleyemaniac]

Just something to check, not saying this is it. How do the ground (-) wires come off your battery, to the engine block or to the chassis. Have seen cases where the body or chassis isn't grounded or the ground strap to the chassis broke and caused some similar problems. You'd think you'd have more problems then that popping up but just something to check cause it sounds like a grounding problem to me. If your lights on the truck are working and you check the connection under the left side there has to be power going thru there (because the lights are on on the truck). So to me if your test light isn't coming on and your grounding it on the back of the truck somewhere the ground is whats not making the complete cercuit. Just take a jumper wire from the battery to a nice clean spot of metal on the chassis and see what happens.

[cold one sd]

You might find that the fuse panel inside your vehicle is for the tail lights and the one under the hood has the fuses for your trailer connections if the hookup for trailer lights is factory.

[shizzy]

You might find that the fuse panel inside your vehicle is for the tail lights and the one under the hood has the fuses for your trailer connections if the hookup for trailer lights is factory.

my 03 Ranger has a seperate "Tow/haul" fuse under the hood.

when I first bought it and hooked the trailer to it I wasnt getting any running lights. brakes and signals on the trailer worked, but no running lights. I popped in a new fuse and all was good.

might be worth a check since the Explorer is similar in build to the Ranger.

[JacobMHD]

Sorry, i didn't get time to work on it last night after work.

If the fuse was blown, why would the lights have worked only on the night that the roads were wet?

[Klink]

Sounds like a bad truck to trailer Ground. Take a jumper wire to bare metal between trailer and truck frame to test.

[JacobMHD]

Klink-

When testing it at the plug, wouldn't there be power even without a trailer ground because I grounded the tester to the frame?

[Jeremy airjer W]

Depends on how good of contact your tester made to the frame. I use a jumper wire from battery ground so there is no question there there is or is not power at the plug. If there isn't than I know I need to check wiring/connections/fuses on the vehicle. If there is power than I'll hook the test light to the trailer plug ground and recheck for power. If there is none than I know the plug ground is the problem. If there is power than I know its the trailer that's the problem.

Depending on the production date there are up to four different relay/fuse boxes that need to be looked into. Two separate ones for fuses and depending on the year two separate ones for relays.

Since none of the lights work (park/turn/brake) than I would also be suspicious of a bad ground wire or pin inside of a connector. It wouldn't be the first time I have seen a corroded pin or loose pin in a factory connector.

[Rivernut]

Not an electricl guy, but when Radco put mine on my '99 explorer, they had to run a seperate power wire to the battery. They told me that if the truck had yellow signal lights vs. red, you needed that extra wire to the battery. Otherwise there would not be enough voltage to the trailer. Hope this makes sense and helps.

[BobT]

Good return path (ground) is critical. Rust, mud, dirt, etc. all degrade the connection and will interfere with both power and testing.

[Jeremy airjer W]

Not an electricl guy, but when Radco put mine on my '99 explorer, they had to run a seperate power wire to the battery. They told me that if the truck had yellow signal lights vs. red, you needed that extra wire to the battery. Otherwise there would not be enough voltage to the trailer. Hope this makes sense and helps.

They had to run a converter that probably had its own power supply. There is no way to directly hook up trailer wiring to a separate brake/turn signal setup (red brake light/yellow turn signal or any setup that has the turn signal on a different bulb than the brake light). His explorer also has factory trailer wiring which may have not been an option on the 99.

[JacobMHD]

I am bringing this back to ask for a reference. I have not had time to address this issue and would like to bring it in to have someone else fix it. Can anyone recommend an auto wiring guy in Fargo Moorhead that they have used before?

[Jeremy airjer W]

I left a message with my buddy Aaron. If there's a guy in Moorehead he should know. I'll get back to you as soon as I hear from him.

[jeffreyd]

were you able to check the fuse for the tow lights? i ran into this several times with fords, did not have any reasoning but that the fuse would blow. if you do not have power back to the plug, the first place to start is in the front. so if you find the fuse blown replace it, then hook your trailer up. if it blows again then you can isolate it to the trailer plug or trailer. that was were most or our issues where was in the plug when people would unplug the trailer rather than pulling the plug out they would pull on the wires which in turn caused them to come loose inside. What type of plug does your explorer/trailer use?

[JacobMHD]

After digging further into the wiring, I found a lot of corrosion on on the wires. I think it's going to need a professional to get it right.