I have '95 Ranger XLT 3.0L, 110k mi.
When I step on the brake, the brake lights go on AND so do the right-side turn lights and the dashboard right indicator - solid, no clicking, even if right signal on.
When I have the right signal on (no brakes) the dash indicator blinks (with clicking sound) AND the brake lights also flash. (Confuses drivers behind.)
Normal operation on the left side.
I was thinking I have a short in the wiring harness, but looking at this site makes me think the multifunction switch is bad. What y'all think?
I've noticed a lot of MFSwitch problems involving melted wires, or brake lights and turn signals, but not these exact symptoms and almost exclusively on the left side.


BTW, newbie to this site

 

I am assuming your Ranger has separate amber turns and red brake lights at the rear? Some did, some didn't.

Did you just buy this truck with this problem? Or did it suddenly happen, it worked fine before?. Have you done any work at the rear, any trailer wiring done?

I am trying to figure out if this is a component failure or someone's wiring mess.

 

It's got amber turn lights.
I've had the truck for over 10 years. It's always had mild electrical issues (dome light not going off, occaisional boop sounds from the dash, random wiper wipes, etc.[hence 'HauntedRanger'), and last year it suddenly developed these turn/brake symptoms. I fiddled with the wires and connections to the MF switch and brake-press sensor. I don't think that cleared it up right away, but it was back to normal a few days later.
I don't see any thing to indicate the wire harness has been damaged or disturbed. That's when I started looking online and found this place. Seeing all those other MF switch problems makes me want it to be that because it's relatively cheap.

BTW, how does one add tags to a post?

 

Ok, sounds like it should be a failure of some component, I would agree and try the multi-function switch replacment.

 

I finally got my MF switch in and installed it. Talk about easy.
But when I stepped on the brake, I got the right blinker lights solid, and when I put on the right turn signal, all brake lights (& rt turn sig lights) blinked.
So I'm thinking something in the harness. I've noticed in the forum that a lot of brake/turn sig problems start with the trailer electrical connection. I've looked there and see no corrosion (corrosion seemed to be at the root of a lot of those problems).
I saw one post (for an F150 I think) that mentioned symptoms like mine and he traced it to the harness cable squeaking between the wheel well and body panel (I think) and getting abraded, then shorting.
As far as I could see, the cable didn't seem to squeeze through or by anything.
Can you think of anywhere else abrasion might happen? And how would I track it down?
I've got a voltmeter.
Could it be something else?

Thanks for your help.

 

You have a short circuit between the brake light and the right turn signal circuits.

Start at the rear of the truck and disconnect connectors in the harness that goes to the RR tail/stop light assemblies, one at a time, until the cross-circuit effect stops. You then know which segment of the circuit has the fault.

The 95 EVTM doesn't show any wiring diagrams that would support separate brake/turn signals, so it's no help in identifying the circuits, connectors, or harnesses involved.

 

So you do have a trailer connection? Did you install that recently? I know you said the truck has worked fine for years, but I just want to make sure this trailer thing is correct.

Trailer connections on rangers and explorers with separate amber rear turns are not hooked up normally. That's because most trailers have the combo single red rear turn/brake lights. So the separate rear brake and amber turn circuits need to be combined together.

I worked on a explorer with a trailer tow package on it, and it had a special connector in the back just for a trailer connection. I had to go to the store and buy a adapter(which they had in stock, could not believe it) and plug it in at the rear to get the correct trailer light logic. What Ford did was to use a multi-function that still had the combo rear red function, and ran these wires special back to the rear just for the trailer connection.

If you do not use this special connection or you do not have it, you have to go to the store and buy a special box they sell(usually in stock also) and this box will combine the red stop and amber turn wires together to run a combo red only trailer setup, but will not mess up the vehicles separate systems.

 

There is a little cable hanging down from behind the bumper with a 3-prong input receptacle (is there a simpler way to say that?) that has a little attached cover to keep out dirt. My father had the truck before me from '97, and he never added a trailer connection. Also it's got that black corrugated tubing around it that makes me think it's factory. Do you know if they did that?
I don't use that connection. It and the cabling near it doesn't seem corroded or disturbed.

When the weather gets better, I'll try to track it with a circuit tester (got it yesterday).

Electrical stuff sux.

 

If you don't use that special connection, and don't use the box either, and you have a 4 prong or other trailer connection, then that's going to be a problem. On the 4 prong trailer connector, white is ground, brown is the running lights, and the other two colors are the right brake/turn and the left brake/turn. There is no way for you to connect to this setup with your truck with separate amber turns without one of the two methods I mentioned. If you or someone has tried to connect this up, that certainly can cause the symptoms you are having a problem with.

 

I looked on Autozone's website and do not see the small harness plug that I got for that Explorer. I believe the Explorer I was working on was a later model than yours. But I did look up your truck, and they do make adapter harnesses for it, and they have a built-in converter box also. Here's the one they have in stock, it's made by Hopkins and is Autozone part number 40215. It's $29.99. If you can see the picture of it below, you will see it has a tee connector like a regular truck would have to tap into the light harness, but after that is has another black box that is the converter/combiner, and then it goes out to the trailer plug.

 

You could check for continuity at the fuses. If there is a short, you should theoretically get continuity at the fuse terminals

 

I looked carefully and it looks very much like the trailer connector in the picture. There's a slight difference in the middle box thing with the 5 wires going in - there's no label and the box doesn't have the ridges near the plug end. Must've been a knock off brand.
Also, there's a suspicious irregular bump on the back of that box, which makes me think there was a short with a lot of heat inside. Tomorrow I'll disconnect the whole thing, and put the 2 harness ends together to see if that cures it. If so, I might wait on replacing the trailer connector.

This must've been put on before my dad bought the truck, because I could see a casting mark on the box that said it was produced in '97.

 

I removed the t-connector from the harness, reconnected the harness to itself, and TADAH! it all now works.
I cracked open the black box thingy with the irregular bump on the back, and sure enough, there was a short inside. There's a circuit board with some resistors inside, and it looks like 2 resistors next to each other shorted causing some burning. Guess I'm lucky the truck didn't burn.
It's a solid casting around the circuit board so I had to crack it with a lock breaker.

In researching online before jumping in, I noticed a lot of MF switch and trailer connector problems, including quite a few that involved melting plastic. There ought to be database of these problems/solutions. Like the recall listings website, but for smaller problems. Maybe that would put too many mechanics out of business.

Thanks for the hint about the after-market trailer connector, and the other suggestions too.