Hi All.

Still trying to get some problems sorted out on my Excursion before I can put it on the road. The issue du jour is my brake lights and turn signals.

-L or R turn signals on by themselves mostly work, but there is a very dim flashing on the opposite side (L signal on normal, but R side lights up very dimly, and vice versa
-Turn signal on with brake on also, they go double-speed and become very dim.
-Brake lights by themselves, rears light up but a very dim light noted on front end as well.
-Hazard lights very dim all 4 corners
-A few weeks ago when I brought it home, when brake and turn signal applied, nothing lit up (though turn or brake worked on their own). Haven't been able to duplicate since.

I pulled apart the rear lights. All the bulbs look good (2 intact filaments on turn/brake bulbs, sockets are not corroded. I took turn signal bulb out when turn signal activated, it sped up to double-speed like you would expect it to do (replacement notification feature, right?)

Any suggestions? Does it sound like a bad ground I need to search for along the wiring path? It has the trailer wiring harness. Not sure if it looks stock or if there have been some alterations made (see photos if they're helpful at all). Any thoughts on where to start? I'm thinking not a fuse problem because nothing flat out wont light up. Relay vs ground? Truck does have some rust. Any help appreciated (keep it simple though, I'm not an electrician). I'm getting frustrated...

 

Probably a bad ground.

Check the brake/tail light grounds first.

 

We had something like this happen after our Ranger was rearended. The 7-way trailer plug was damaged and caused all kinds of weird stuff to happen. Now the Ex should have a separate system for trailer lights but it's still a possibility

 

Check your 4-way (emergency) flasher it's about the only thing that bridges the left and right turn signals AND is wired to brake light circuit.

 

multi-function switch also.

 

What year is this Excursion?

There were changes in the design of these circuits over the six year course of the product's run.

 

Subscribed.

Ground issues cause a lot of bleed over on trailer wiring. I wouldn't know where to start on this.

Especially since it's on all 4 corners?

 

If you have a brake controller, disconnect it and see what happens.

Ed

 

He has a 2000 I believe...

 

Thanks for the feedback so far, everyone. Sorry for the hiatus, got 4 sicks kids at home.

So:
Project- It's a 2000 7.3L Limited
Ed- disconnected brake controller, no change
Arodder- Yes, I'm getting weird stuff happening on all 4 corners. Lt signal will cause dim flashing on right side front and back, vice versa. With brakes on though, front turn lights don't dim, only rear. Rear high center brake light unaffected.
Alaskan- multifunction switch would be the lever coming off the steering column? I haven't taken that apart yet...
Misky- I was just checking out some vids on how to access that turn signal/hazard flasher. Awkward to access, but I will pull that out tomorrow.

I tested all the fuses. Found 1 blown (floor console auxiliary power point) and replaced it with no change.

I looked up what the brake/turn lamps are supposed to be from owner's manual. It says "turn lamp rear" should be 3156k and "tail/stop lamp" should be 3157 K. The turn and brake lights come from the same bulb, so are those 2 numbers just the 2 filaments in that bulb, or should I change the bulbs in there from 3157 to 3156?

When looking for a bad ground, where would one find that typically? Would it be grounded to the chassis close to the rear (1 for each side?) , or would it most likely run all the way up to the engine compartment and ground somewhere there? I see a number of grounds up there (and I'm sure there are a number that I'm not seeing too...) I tried looking around the rear of the body, pulled up some carpet etc. looking for any grounds, but only saw what looked like one by the rear AC area on passenger side rear. I tried following the wiring harness but lost it behind the bumper amongst everything.

I did see some loose connections behind panel under steering wheel. Looks like there was maybe a CB radio or something at some point (a coax cable with some regular wiring hanging loose). Also under the hood by firewall on driver's side, there were 2 wires just kind of hanging out there. Probably not that helpful on their own, but I'll include a couple of pics just in case.

Thanks for the help so far.





To test if it truly is a ground issue, then what if I were to hook up a wire the ground from each of the tail light, and create a new ground running up to a known good ground? If there were a ground issue, then should the symptoms clear up if I did that?

 

Any resolution to this problem as I'm having the same issues. Ironically started after replacing fuel pump. Checked all fuses and the only one not checking out is #15 under dash. When I pull it the fuse checks out fine. But plugged in it's not zeroing out. Leads me to believe a possible brake light switch issue as I've changed a couple out on 2 other fords I've owned over the years.

Symptoms: Standard flash rate until brake pedel depressed then fast. Weird thing is outside the truck the front flashes on correct side but rear flashes opposite. Brake lights are dim as well when applied.

 

Sorry for the tardy reply X40.

So it ended up being a bad ground. Got a set up a new ground from tail light to a clean spot on chassis and symptoms cleared up. I had already gone through brake switch, multifunction switch, checked all fuses, etc. Truck has a bit of rust on it (East Coaster) so I half expect to encounter more electrical gremlins down the road.

As an aside, I started having similar problems on trailer lights first time I towed a trailer with it. Turns out there was to much rust/debris in hitch receiver that it wasn't getting a proper ground. Hooked up a wire between trailer and truck, and it worked fine. Will sand-blast the receiver hitch to permanently fix problem.

Hope this is helpful!!

 

Could you maybe throw up a picture of what you setup for a ground- i am running into the same issue, but just the back lights. Going to pull the bumper this weekend, but I suspect a ground issue too.

Thank you!

 

I recently got a 69 f-350. am working through the bugs and I have a complete duh moment.......
this is what I have,
while trying to get the trailer light harnesses to work I discovered;

that both turn signals work

but only the right break light comes on......

with foot on break left turn signal works with and right break light is on.,

with foot on break right turn works and left break light is on........

but with no turn signal only the right break comes on

so how is it that all lights come on but when not using turn signal I only have 1 break light,

is the same on truck it's self not just the trailer jack

gypsy
69' f-350
78' f-150
79' f-600
96 f-250 xlt

 

I was informed yesterday that my brake lights were out. Turns out it was caused by my cracked turn signal switch. If I carefully place the turn signal handle in a certain place my brake lights will work, If not set just right the brake lights will not work. I tried to order a new switch from CJ Pony Parts but got stuck in the "are you human" screen.