Hi ,
First off, I apologize if I posted this in the wrong forum

I have a 2003 E350 ambulance chassis with a 7.3 that I am converting to a truck with a flatbed. i am up to the wiring and I am having BIG problems...I have rewired the flatbed with new wires and LED lights.

The chassis has 6 wires running to the back:
Green - right turn
yellow - left turn
Brown - tail/clearance
black w/green stripe - backup lights
Blue - brake lights
Orange - dont know what the heck its for!

The problem I am having is making the brake lights work...I have never worked on a vehicle with an independent wire for brake lights. I have done the following to try and make it work.

attempt #1
a. hook up the turn signal wires - turn signals work correctly...but no brake lights
b. hooked the Brake wire to the left turn signal...brake lights work, right turn signal works without left break lamp...left turn signal does not flash but both brakes lights are on
c. hooked Brake wire to right turn signal - exact opposite problem as the left

attempt 2#
someone told me about a tail light converter...you can purchase them at any parts store...it supposedly takes the 3 wires (RH, LH and brake) and converts the to 2 (RH/brake & LH/brake) my results (I purchased 2 converters thinking the 1st one was bad):
a. hooked lights through converter - RH turn to RH turn, LH to LH and the brake wire to the proper wire on the converter
b. brake lights do not work - if the pedal is tapped the brake lights flash for a quick second very dimly
c. turn signals work but are barely brighter than the tail lights
d. if the brake is applied with the turn signal on the corresponding turn signal will now blink at the appropriate brightness
e. without the brake applied the turn signal will flash at the same time as the front turn signal...if the brake is applied they ALTERNATE!

I have read alot of forums and articles on the internet in regards to tail light wiring and alot of them talk about resistance (or a lack thereof) with LED lights so I tried this:

attempt #3
a. I hooked a standard tailight to the truck through the converter (had to go through the converter because a standard tail light does not have a separate wire/bulb for brake light)
b. I get the same result as attempt #2 with the turn signal except DIMMER still
c. I also unhooked the LED's altogether thinking maybe they were the problem...this is not the case...same results

I would appreciate any help anyone could provide...I am at a complete loss on this and have been working on it for days now! please HELP!

thanks
Scott

 

Are the replacement lights Dual, or Single filiment? This is important, Next its important to make sure you have the correct wire grounded, and the other two sorted out for park circut and signal circut. signal circut would be the brighter one.
If you have one light piggy backed off of the other one, i would bet there is a wire crossed between park light and signal.
Dim lights lead me to think there is a ground wire problem. you said you have a two wire light, if i were to assume for a moment... That would lead me to think they ground through the housing, and you said your putting them on a steak bed which i assume is made out of wood.... Hence the ground issue.

I would start with proper grounding....

then wire up the park circut so it turns on with the lights....

then find the brake light wire and wire it in; keep in mind here would be a potential problem if you have the lights piggiebacked, because if you do then when you add the turn signal then both lights will come on as if it was on 4-ways...

once this is sorted out then add the turnsignal...

BTW i double check the wiring with a multimeter before hooking things up...
Hope this helped, Mark

 

Welcome to FTE Scott.

I'm moving your thread to the 1968 - Present Full Size Van forum. Since this is a van chassis, these folks should be able to assist you more than the Super Duty folks.....with the exception of PA-Mark who posted above.

Best of luck with your issue.

And thanks for posting Mark.

 

Hea Scott, got any updates?

Mark

 

Hey Scott,
Im having the same EXACT problem as you had, just wondering if you ever found a solution to your problem!!

Thanks!!
Wyatt

 

i assume the ambulance chassis has a separate turn signal bulb. usually the large orange arrow.

 

My guess is the OP poped on here got his answer then split.... It happens here... Just read the answer i gave the OP and see if that works for you, if not I can try to help if you give me some more info