I have a 2005 Excursion 4x4 Limited 6.0 diesel. I've read several threads on this issue and need a little help knowing what to check next.

I had someone pull alongside me today and tell me my brake lights were out. Sure enough. I double checked and nothing at both lower lights and also nothing at the third brake.

So... here's the short version of the things I've checked so far:

1. no brake lights when pedal depressed.

2. running lights work fine

3. turn signals work fine

4. hazards work fine

5. brake lights DO illuminate when I press the brake button on my trailer brake controller

6. checked power to the green with red tracer wire going to the brake light switch on the pedal. 12 v present continuously

7. checked power to light green wire. 12 v present when pedal is depressed. 0 v when pedal is released.

8. checked power to tail lights (wish I had tried the trailer brake controller sooner, this step would have been unnecessary). voltage present (I think 10-12 v) when the running lights were turned on. 0 v when brake pedal depressed. I suspect now that I would have 12 v when squeezing my trailer brake controller button.


After reading several posts, I was pretty convinced it was the brake switch at the pedal. But since I'm seeing the voltage pass through the light green wire when depressed....

I know the wiring to the lights are good because they work when pressing the trailer brake controller button.

So... Do I need to dig into the multifunction switch that I've been reading about? Does the power go from the pedal switch to the multifunction, then to the trailer brake controller?

Any tips on what to check next would be greatly appreciated. I'm really hoping that I don't have to dig into the column to check that multifunction switch!

Thanks in advance!

Ken

 

In my professional opinion, your problem stems from a hint in your first sentence- '6.0 diesel'.
There's not much hope without a complete replacement. Sorry.

 

OK, I must be working too hard; my wife says I'm grumpy at home, too...

Ken, I'm bumping this back up to the top so you can (hopefully) get some help! Good luck!

 

LOL! It's actually been good to me so far! Most of the things it's needed, I've solved simply with the help I've found here!

I'll probably take a look at the multifunction switch tomorrow morning. I work in EMS and just haven't had time to tear into it yet.

At least I can use my trailer brake controller to manually light up the brake lights so I can keep driving it in the meantime.

Before I realized that worked I was using hand signals. I'm pretty sure no one under 30 has any idea what I was doing! LOL

 

No doubt! The only hand signal they've probably ever seen is the 'you're #1' finger they get when they cut someone off!

 

According to the schematic the high mounted stoplamp does not run through the multifunction switch. You could make sure the high mounted lamp is functioning with your brake controller then try your brake pedal and see if it is the only one that illuminates, if it is then I would dig into the multifunction switch.

 

No, it isn't the problem. Leave the steering column (MFS) alone.

You have an open circuit in the light green wire circuit between the switch connector and the next splice in the circuit (S240) - probably a broken conductor inside its insulation very close to the switch connector.

No. Power from the activated switch goes to splice S240 which hardware-ties the switch output, the trailer brake controller signal, the high-mount stop lamp, and the input to the MFS together. That splice should be in the main wiring harness bundle near the takeout for the brake pedal switch connector.

Good luck!