Hello, nice forum and site!
Lots of good info.

A contracter I am working for has a 2001 F-550 chassis cab, and the turn signals quit working one day, but when he tried them both to the right and the left and neither worked, he turned on the four ways and they worked, so he tried his turn signals again and they worked fine. About a week later, the turn signals and flashers quit working completely, and the brake lights quit working aswell, though the running lights worked.
Later, the brake lights started working, though no turn signals. The 30A mega fuse under the hood was blown, which apparently is the fuse for the multi switch lever for the turn signal, wipers and brights/dims.
After replacing the fuse, and the two relays under the dash (we didn't know what they went to, so we just replaced them) still nothing worked.

If the brake pedal is pressed, the brakes light come on, and switching a turn signal will cause the rear tail light on the sorresponding side to dim to what would be regular running light brightness, but it won't flash.
Also, neither parking light or turn signal light will turn on at all up front.
The parking and turn signal lights do work when the head lights are on though.

The truck has a Reading utility body installed, and he did the wiring to the brake lights himself, and they are soddered and shrink wrapped at the connections.

Is it simply a ground problem?
Any ideas where the ground problem would be?
Is it possible that the trailer plug (7 pin) could be short out the whole system?
We tow the trailer a lot, and when the trailer is hooked up, it has running lights and brake light, but iof I recall correctly, the turn signals don't do anything.

Any suggestions as to where to start the troubleshooting process?
All the bulbs are good.

Thanks for any help or info!
-Stu

 

I would check/replace the turnsignal flasher. I am assuming all the lights worked after the body install, and this is a failure later on.

If this just happened after the body install, I would suspect a wiring problem to the body, and we can pursue that.

 

The body has been installed, and the lights have functioned properly for about a year so far.

Thank you for asking about the turn signal flasher, I forgot to add that to my first post.

We bought a turn signal flasher from a dealer, but it is not in the fuse box under the dash, or in the fuse box under the hood. the owners manual doesn't show it either. As of yet, we have not found it, but we can hear something buzz or 'click' much like the turn signal would if it were functioning correctly, though it sounds randomly when we turn on one of the turn signals, only happens every once and a while and not everytime.
The noise is coming from somewhere inside the center of the dash. What could that be?

everyone is surprised when we say the flasher isn't in either fuse box.
Any idea where it would be?

Thanks for any help,
-Stu

 

I found the location on a 2005. There is a slight possiblity it may be the same on yours.

It's underneath the dash, on the driver's side. There's a big wad of wires that come up out of the driver's side kick panel. They branch off and a large bundle runs along the bottom edge of the dash. If you follow it up, and then run your hand along the lower edge of the dash from the driver's side corner, you should feel a few wires branch off and go to the flasher mounted low behind the dash.

 

Thank you very much Dave F.
I will look tomorrow, and let you know.

Have a great evening,
-Stu

 

It's fixed!

It was the flasher relay. It was located behind the dash in the radio area. Once the dash cover is removed, you have to reach through to opening beside the climate control and there are two connecters plugged into a large plug that has a cover clipped onto it. If you take the cover off, the flasher relay and another relay are in there.
Might be worth writing down in case anyone needs to do this on a 2001 F-550 chassis cab in the future.

Thanks for the help, :-)
-Stu

 

Your reply should do it in case anyone does a search. Thanks for writing back in.

 

I have a very similar problem. 2001 F350, No flashers, no turn signals but also no brake lights except for the high mount or 3rd break light. All fuses are good, I have already replaced the flasher relay, the bulbs in the rear, they were ok to begin with, and the multi-purpose switch. I'm at my wits end...please help!


Thanks,


Mac

 

Wow SG4145,

Sounds like you have quite a problem on your hands!

One thing that might possibly be an oversight:
Did you test all your fuses with a test light?
Because I know that some times, a fuse will 'look good', but in fact be bad.

Maybe you actually have some borken wires somewhere.

Hope you get it fixed,

-Stu

 

Sounds like you still have a problem in the column. Your brake fuse is good, and your brake switch on the pedal is good, since the third brake light works. That same signal that works the third brakelight, splits off and goes up in the column to the multi-function switch. When the multi-function switch is in the mid position, the brake signal goes through the switch and onto the wires that go to the rear.

I am assuming even the front turns do not work. If they did, I would say the wiring in the column is good, and you have a problem with the wiring going to the rear.

If none of the turns work, then I would look in the column again. Make sure all the plugs are plugged in tight in the column and down at the bottom too.

 

We tested all the fuses with a test light...so we know they're all good. None of the turn signals work. The brake lights were working until yesterday...as far as I remember. The really strange thing about when all this began to occur is that before the flashers quit working they would flash really slow...I mean like stay on for a couple of seconds before going off... This seems like it all started with a bad ground on my trailer feeding back through the system. I got the ground fixed by running a new ground from the trailer harness to the trailer. Then the next day the flashers & turn signals quit...I had been pulling some mountains with the flashers on for an extended amount of time...so when they quit I just figured that I burned up the flasher...I checked all the fuses & they were all good. On another note...I wonder if I could have broken some wires under the bed...I had the gooseneck coupler slam down on the ball the other day...could I have broken wires without causing a short & blowing fuses? Just wondering...

Thanks,


Mac

 

I believe like I said, your problem is going to be in the column.

Look for a lightgreen wire going up in the column. This comes from the brakeswitch, and is the same wire that goes to the third brakelight. Get a testlight, and you should have power on this wire going up in the column when you hit the brake pedal.

Coming out of the column you should have a lightgreen/orange wire(one rear brake turn) and a orange/lightblue wire(the other rear brake/turn). With the turnsignal switch in the mid position, you should have 12 volts on both of these wires when you push on the brake pedal.

If you have power going in on the lightgreen wire, and none coming out on the other two wires, the problem is in the steering column.

 

Ok...got it fixed...as it turned out it was the flasher all along...the aftermarket flasher I got from NAPA didn't fix the problem but when I got a flasher from the Ford dealer...viola!...it worked...


Thanks for all the help...


Mac

 

Wow,

The flasher was the culprit again!

-Stu

 

The moral of this story...always rely on Genuine Ford Parts!