Thanks!

So after a buddy replaced my brake light switch for a little cash and beer I seem to be having the same problem again. The Brake lights, turn signals and reverse lights were working and are not working again. they only worked for a few days after the BLS got replaced.

This was the same problem as before. So if I ask a few questions I hope that someone has experience with this problem. I did as much research as the googles would let. The most logical conclusion for this problem to repeat it self is a bad ground.

This will be my first time using a multi meter in real world applications. Learned a little on youtube and school.

If someone has a little time and could help me with this you are really cool!
Im just going to spit out some questions. At this point any insight is valuable.

1985 long bed 4spd B&W 300 1bbl NP 245



1) Where should I test?

2)My buddy said he could visibly inspect the old BLS and see it was messed up(maybe melted). Does this indicate anything or help with diagnostics?

3)The truck was recently painted and also had after market lights installed. (previous owner) How heavily could this come in to play?

4) The turn signal doesn't go back in to place after a turn. Also, it is an aftermarket steering wheel. It has no horn connected either. How heavily could this come in to play?

5) The trailer wiring seems odd. I have little idea what I'm looking at. Where could I start with that potential rats nest?


Any information is appreciated at this point because I have put this problem off long enough! I love the truck but can't afford tickets!

Thanks again, Justin

 

I am glad you got a multi-meter, but for this problem you should go back to the store and get a testlight. If there is a harbor freight near you, they have a nice one I bought on sale and it works well and will poke through the insulation in the wire. But the main reason to use a testlight is load. You need to load these circuits down to test them, and a multi-meter does not present enough load and can give you false readings. If you leave the bulbs plugged in the circuit they work ok, since the bulb is enough load. But if you take the bulb out and start probing down in the bulb socket, that's where the problems start with a multi-meter.

You didn't say anything about your running lights. I assume they are ok?

The first thing to do is check the brake circuit, which does go through the turnsignal switch. Double check the brake switch. Take the testlight and probe the switch. One wire will be hot all the time, the other wire to the switch will be hot only when you press the pedal.

If that's ok, make sure the turnsignal lever is in the middle position, and then look down at the bottom of the column, or you can look at the turnsignal switch itself if you have the steering wheel off. What you are looking for is a orange/lightblue wire and a lightgreen/orange wire. These two wires leave the turnsignal switch and go back tot he rear lights.

With the lever in the middle, and good voltage coming from the brake pedal switch when the pedal is pressed, probe these two wires. You should have voltage on both when the pedal is pressed. If you don't, you have a turnsignal switch or a hazard switch problem.

 

I had the same problem. In my case the turn signal switch broke and when I would turn the wheel parts of it would ground out and blow the fuse.

 

Im very excited to start working on this. I'll be at harbour freight tomorrow buying a test light.

I have been under the impression that something may be causing the BLS to go out. Perhaps a bad ground or something. Is this kind of malfuntion possible?

Anyway,I'll probe how you said and have some results tomorrow.

 

One quick easy check is at the rear spring area on the drivers side behind the axle there is a connector. If you disconnect it there and turn on running lights or signals and test the front side that would let you know if you have power comming back or not. If not the next connector is near the brake booster. Testing there will show if you have power comming from inside the cab. I had a similar problem a few months back and it ended up being a ground wire broken inside the sheathing. You couldnt see or feel it. I found it by trsting continuity on each wire.

 

Here is a link to that thread if anything in there can help you.

https://www.ford-trucks.com/forums/1...ed-up-bad.html

 

Thanks, yall are too helpful! I mean it! Im glad to have more things to try. After class im going to write out all the suggestions and tips and start working! Thanks again

 

Here is a link to some troubleshooting information that may or may not help. I thought I would put it up here for you just in case it will come in handy.
Ford Truck Enthusiasts Forums - Grubbworm's Album: Troubleshooting help, for anyone that needs it.

 

The brake light switches are not known for giving trouble. They do go bad once in awhile, but I have had Ford cars and trucks where the switch has never been replaced in 30 years.

 

Got to looking around and this is what I found!

It seemed like the BLS was fine but I just left the replacement in there.

I found three new fuses. Two of those were blown. This is probably why my light are working BUT WAIT!

I also got to looking at the wires in the back. Who ever added the trailer wiring did one HACK of a job.

There are wires that go no where and unnecessary splices.

The ground from the trailer wires is (soldered?) to the bumber.

It just looks bad from the axle back. Everything going forward looks good.

I had no luck with the test light. I tried to make it happen but IDK. It works, I tested it by connecting the clamp to the + terminal and touching the - terminal on the 12v battery.

WhenI tried wires on systems that I know were working but I had no luck.

So whats next?
Should I find a wiring diagram and just correct everything from the back goin forward?

 

Use your test light in the front end of the rear connector. Use sand paper, steel wool or brush, anything to scratch to metal on the frame or spring and attach ground there. Then test the terminals inside the connector. I forget the color codes off hand but they are in my thread.

Say turn on marker lights. Stick point of test light in that terminal. Light should come on and stay lit. If you test signals the light should flash with the clicking of the relay. If you have power there then your problem in the light side of the connector.

 

I had the same problem and it ended up being the turn signal cam. Ended up replacing it and everything has worked since. Need to pul the steering wheel and check to see if everything under there looks OK.

 

I made a video. To kind of show whats going on. The second video is one that I recorded a few months ago with another problem that I will be addressing when I address this problem. xman and lcguy may be correct about the turn sig cam. I'm gooing to keep practicing with the test light

Is it possible for a bad ground to be blowing fuses. Like I said, my friend replaced the fuses and the lights had started working. I havn't replaced them again to see if thats why they don't work. If I do replace them and they blow again then should I be concerned with grounding should I look elsewhere first?

Jayzdaddy: Do you mean checking the trailer connector again or the connectors at the taillights? Thanks for your help with learning the test light better. I'm going to keep trying.

xman:I think you and lcguy are on to something here. My steering wheel situation is a little whack at the moment.
lcguy: was the turn signal cam blowing your fuses?
I think I'm going to see about pulling an entire SW and a little spacer part from Pull a part. see second video


franklin: Thanks for the heads up. after looking at the part I felt like it was a good design and probably resistant to premature failure.

grubbworm: Thanks for the link!

 

This is a video from a few months ago. I plan on changing the turn sig cam, fuses and adding the spacer/bearing that is missing.

I post this video to give a better Idea as to whats going on behind the SW

 

The problem im having trouble with is brake, signals, AND back up lights arent working. The reverse light switch originates from the tranny while the park, brake, signal originates from the cab. Thats why im thinking you have a ground issue in the rear like i did.

This is your harness comming out of the cab. The larger front connector contains your power for all rear lights as well as front lights and such. It located under the brake booster.