Hi. Been using this Forum for years as reference, but finally am stumped on a problem and hope someone can shed some light.

Vehicle is a 2005 E-350 6.0PSD with Sportsmobile 4wd conversion.

As the title says, I have no brake lights. I've researched the topic, but am now stumped. Here's what I know with my trouble shooting.

- I have everything else working (turn signals, hazard flashers, running lights).
- Power to input side of brake switch at brake pedal
- Power to output side of brake switch at brake pedal when pedal is pushed
- Bulbs are good
- Fuse is good
- Just replaced the multifunction switch (thank you PStruwing for your post showing how). Apparently the old one was good as no change with the brake lights, but now I have a new MF Switch.
- From schematics I can find for similar vehicles (Ford trucks or other year vans), it appears that the LG wire at the MF Switch should be from the brake switch at the pedal. I am not getting 12v there when I push the brake nor do I have continuity from the output of the brake switch at the pedal and LG wire at the MF Switch.
- I also checked for 12v at all other wires at the MF Switch when pressing on the brake pedal and couldn't find any that seem to be it.
- There are no wires at the MF Switch that match the color of the output wire of the brake switch at the pedal, so I assume it stops somewhere else first. I cannot locate a schematic though to give more info.

So there you have it. I think I have narrowed it down to between the brake switch at the pedal and the MF Switch. Any help would be greatly appreciated. Help could include suggestions or schematics / wiring diagrams that may help me out.

Thank you!

Phil

 

The drawings are for 1999. Assuming they the same. If you look at drawing#2 LG changed to RD/LG at connector C228 which is located at base of steering column, to multifunction switch. That is where I'll be looking at for loose or broken connection. Good luck.
Robert

 

Thanks Laor. I think I recall a RD/LG wire at the MF Switch. I'll check it out today.

Phil

 

Closing this out.

I found the culprit. Is a short in the aftermarket third brake light in the penthouse top added by Sportsmobile.

A member on the Sportsmobile Forum pointed out that there are two fuses in the brake line wiring. One before the brake position switch and one after (F2.39). I didn't know about the one after. On examination, it was blown. Replaced it and it blew again. Then started tracing down the short and found it in a very corroded aftermarket third brake light assembly.

Glad this is behind me.

Phil

 

Phil thanks for adding your discovery and its fix----can't hurt to know this sort of thing.

Those who don't know about the third brake light or HMSL (High Mounted Stop Light) can't imagine how much it affects other things. It can even cause the Speed Control (aka cruise control) to not work too.

Reps sent---see ya at SMB!