I've got a 1995 F350 CCLB 4x4 460 E4OD
(Overly specific for this issue, I'm sure, but better safe than sorry)

Basically the entire truck has been converted to LED lighting, aside from the Cargo/3rd Brake Light and the Overhead Dome Lights. That being said, I'm having some... interesting... problems.

The Turn Signals, and Brake Lights are all LED, but for some reason, whenever I mess with any of the brake or turn signal lights, (i.e. inspecting the socket wires or replacing bulbs) and then test them during reassembly, the turn signals seem to only have a weak pulse, like they've not got enough power to fully *click* the flasher?

It's an LED flasher, and there are no resistors in the system, so I have no idea why it does this.
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HERE'S the kicker though... when I finally just put everything back together because I'm tired of fighting with it, and test it fully assembled, they work PERFECTLY! No issues whatsoever! Like it never even happened!

Does ANYONE have any idea what is going on here???

 

I can't add much, but these truck's electrical system is known for not liking led lighting at all (in some specific spots). Someone more knowledgeable than me might add some insight on the why, but it has been reported countless times before.

 

Interesting. Thanks for the reply Encho. I've never heard of that being the case with these trucks.

I have read a couple other threads and it seems that a common issue during this process is corrosion built up in the connectors, however I have replaced all the connectors at this point, so I know there is no corrosion in question.

 

IIRC replacing the third brake light with LEDs makes the auto trans act up--the trans computer watches the light to see when the brakes are on, to unlock the converter, and I suspect it's expecting a better ground signal through the bulb than it gets with the LEDs. Haven't had a reason to look into it.

So when the system is apart, the lights don't work, and when you put the housings back in, it all works again? Almost sounds like the screws are grounding it, except that the housings are plastic, so, there's that out. If you hold the bulbs where they'd be if the housing was installed, does that change anything? I'm wondering if you might have something loose or broken in the harness (or a loose ground point?) that resolves when the harness is pushed a certain way. I don't know the wiring in these trucks well enough to guess beyond that.

Did the truck have any lighting issues before you went to LEDs? I'd ask if you'd tried a different flasher unit, but I doubt it's that given the symptoms. Doesn't seem like the flasher would know or care whether the housings were installed or not.

 

Going to try replying again. Yesterday late afternoon while at work typed a reply, attempted to reply and my computer wouldn't process it. Although my reply doesn't provide any specific remedies, but does convey the issue I experienced with a bad ground and LEB third brake bulb. About five years ago on the way back from the annual Summer trout fishing trip while driving my 1995 F-150, 5.0 SWB Regular cab on the highway using cruise control, I signaled to pass and noticed the E4OD transmission kicked down into third gear, odd I thought because I didn't accelerate any to pass, no vacuum change. Turned the signal off manually after getting back into the right lane and the transmission shifted back into overdrive. Drove about five miles no traffic around me, so I manually used my turn signal and again the transmission shifted down into third gear. Tried this a third time and the same thing happened. The remainder of the drive home I avoided using my turn signals to prevent the transmission shifting out of overdrive. Got home, that evening researched and stumbled upon an old post either this forum or the other describing the same experience. Followed the guidance provided which indicated a bad or lose ground on the grounding wiring stud located on the passenger side inner fender, by the battery, Next morning checked mine and it was lose enough that i was able to tighten it with my finger. So I removed the stud, cleaned it, used a little dielectric grease and re-tightened the stud. Have not had that re-occurring problem since. Two Summers ago I decided to swap an LED bulb into the third brake light, just before the annual fishing trip, but kept the original incandescent in the ask tray, just in case. Ten miles from home, eased onto the highway and noticed my E4OD transmission wouldn't shift into overdrive. Drove to the first McDonald's, five miles away from where I was, pulled into the parking lot and took the LED bulb out of the third brake light and put back the original incandescent bulb. E4OD transmission shifted normal into overdrive as it should. Last Summer's fishing trip, I had removed the OEM size incandescent third brake bulb and replaced it the little incandescent bulb, the size used in roof marker lights. Reason I did that was to reduce the heat build up in the third brake plastic socket, because I have seen so many of the plastic bulb sockets deformed, melted and brittle from the heat generated. I've checked many of the third brake lights in my local junk yards over the years and all of them have been deformed, melted. I'm conscious not to hold my foot on the brake pedal while stopped at a light, put the transmission in neutral and will use my parking brake if necessary to prevent rolling either in an incline or decline. So in my experience the electronics used with the E4OD are sensitive to the load and resistance in the circuit. About two years was able to obtain a nearly perfect condition OEM third brake light off eBay including the original wiring and sockets. Know my reply doesn't answer your question directly, but hope it sheds some light on the topic and others and glean from it.

 

I have had a similar weird electrical scenario with my 2006 Navigator. Almost the opposite direction....I have HID lamps for the fog lights, this was a PO installed "option", that work just fine with the physical components hanging from the wiring loom. When I put everything back together one or both of the fog lamps no longer works. I traced it down to corroded/worn out connectors to the bulb power supply. Visually everything looks great but when you reassemble, then wiggle the wiring the lights flicker off and on.

I highly suggest inspecting and replacing any suspect bulb socket connectors. Solder and shrink wrap is the only option, butt splices are a disaster to your forehead height. If you have not done so already remove the multi-function switch assembly and open it up. The contacts are known to grow green corrosion. Our old 1997 Mustang had a small greenhouse inside the MFS. Being a cheap ba$t*rd I cleaned it up then applied some light lithium grease.

Also remove and clean up the grounds for G100 and G101. Both are used for the turn/stop/hazard lamps.


The ground point is the drivers radiator support, G100.



G101

 

Just for sheets & giggles, I'll add my OBS/CHMSL/bed light/E4OD saga...

Drove a 96 F250/PS/E4OD 2wd with service body & Tommy lift for a touchless car wash company.

Carried 55 gal drums of soap, etc. up against the cab & the rims routinely busted the lens.

The truck got test washed multiple times per service call & just as often developed a flashing OD light & really harsh limp mode which sent it to the shop.

Eventually some body told me it was blowing a fuse & I started carrying 20 amp fuses for I think # 8 but aren't sure.

I left not long afterward and wasn't allowed to delve into the cause cause I was running my *** off across 3 states.

But it was one helluva truck.

 

Thanks so much RLA! Sounds like those ground points are probably the culprit... I had the whole front end of the truck torn apart at the end of 2018 to do a motor swap, and those ground points were undone then, so they probably just didn't get cleaned up when we put it back together...

I have replaced all the turn signals/brake light connectors already, but that was with butt connectors, so I will definitely get them soldered together to eliminate that possibility as well, once I get another warm day (been -22*F or colder all week, brrrrrrr).

Also, I have been into that MFS, several times now actually. I had that same issue with the green corrosion last spring, but got it fixed and it works like a charm now! Good as new!

Will keep updating this thread as the situation develops!