I'm a newbie to troubleshooting my old Ford truck, so I hope my questions aren't annoying to you old-schoolers here...

I've got a gremlin in my rear tail-lighting system, hoping you all can help me understand a few things...

The tail-lights on my 85 Flareside haven't been working properly since I removed my bed to try and replace the wooden bed. That job is still in progress but the bed is reattached and I'd like to drive this baby around, can't do that without a working brake and turning signals.

My turning signals right now morph into hazard signals and both left and right sides flash in unison when the signal is engaged, the reverse lights don't seem to work at all, brake lights don't come on...but thinking back and reading up on the forum here, it seems like grounding is a big issue with these vehicles. AND, that made me remember that there was a weird metal-mesh strap that I disconnected from the rear drivers side of the bed and frame. I haven't re-attached it yet and am guessing that I'll have to re-attach that for any hope that these lights will work properly again someday.

I'm terrible at troubleshooting electrical problems...so I'm trying to understand a few things...(please try to answer in layman's terms)

My question, what is with the "grounding" issues that these trucks seem to have?
Did Ford just crap the bed when these things rolled off the production line and they didn't ground anything?
Have they had electrical system problems all along?
Any tips or tricks for me to avoid electrical system issues moving forward?

Thanks,
JT

 

Ford properly grounded everything, it's just us forgetting to re-connect grounds, and age/rust corrosion that is the final straw, since most grounds bolt to the steel frame or body of the truck.

But in your case of both lights blinking when using the turn, I suspect you have a wire pinched or hooked up wrong back there. If the flashers stop working when you turn the headlights on, that is a grounding problem.

 

The thing to remember with electricity it wants to find the easiest path to ground. If that means going thru another light it will and you will get strange things happening.

I don't know what a complete flare side tail light harness should look like at the light end, so it is hard to say how they get a ground.
Are you using the stock tail lights and if so how many wires are coming out of it? Again I don't have any to look at.

I am thinking from the harness to each light you would have 3 wires *.
right turn / brake light
running or tail light **
Back up light **

Left turn / brake light
running or tail light **
Back up light **
* = may have 4 wires as there may be a ground.
** = shared wires to left & right lights.

Using a test light (can be picked up at any parts store) disconnect the harness wires from the lights and check what each wire does.
Take note of them as they should work just like the tail lights. It they work right with the test light they have to work right when hooked to a tail light ...... if the ground is good.
Dave ----

 

I was having similar issues with my 86 styleside. I checked just about all the grounds except for the one under the drivers side inside kick panel. I drove through a car wash for the first time since owning the truck and had a flood of water come in and pour through the drivers side lower vent in the same kick panel. Magically, my taillights are working great now. I'm guessing it had something to do with that ground. I'm hoping to get in there this weekend to take a look at it.

 

Just fixed a ground issue in the rear wiring of an 89 F150. Fuel pumps were running on low voltage and the taillights were dim. Turns out the ground for the entire rear harness runs through one of the circular connectors on the LH inner fender. Grey one with 3 pins if I am correct. Black wires with white stripe, circuit 57 in the EVTM.

 

See I did not know if Ford ran a ground in the harness or just at the lights. I have not gotten that far with my project yet to deal with light grounds just yet.
Part of my "fun" will be I am using a long bed style side harness on my short bed flare side.
Dave ----

 

I've got an update here...which will cause some of you to fall out of your chairs, but maybe it'll help somebody moving forward...

I found a guy on Craigslist and paid him to come to my house and diagnose the problem. I got totally ripped off but what what he found, I could have NEVER found on my own.

In the drivers side rear tail light assembly there is a small flat metal plate that separates the top and bottom halves of the lamp. Keeps the top white as white as it can be and the bottom red as red as it can be. Somehow, a thin wire that powered the top reverse light had shifted and was behind the plate, the plate had barely cut into the wire and was causing a short. So, it affected the entire system. Also, the ground strap that is in the rear of my bed which attaches from the body to the frame had to be cleaned thoroughly on each end.

The dude diagnosed it over 2 days in my driveway and fixed it all up, works normally now. I'm still pissed about the price, but happy the truck is legal.

Now I need to figure out what's wrong with the fuel gauge.
I put in a brand new sending unit and it worked great...then crapped out a few days later and constantly shows empty.
I do not like electrical problems...

Cheers everyone...
JT

 

Any electrical issues is alway a lot of $$ because it is all time / labor vary little parts.

On the fuel gauge check to see if the wire came unplugged first.
if still in place pull it off and ground 1 side turn key on and see if it moves.
if not you have issues with wiring or gauge.
if it does move then bad sender maybe float fell off?
Dave - - - -

 

I've done the little piece of wire trick and watch the gauge go straight up to full.
If the float somehow popped off, LMC is getting a nasty phone call!
I'll have a look and send updates!

 

Small update...brand new fuel sending unit, less than 2 months old...I think I found the problem...
Does anything look odd to you here?



I'm going to now try my luck with a plastic float off of Amazon. Not a SINGLE auto parts store near me in the DC area carries a replacement float.

 

Nope looks normal to me for Photobucket, picture not showing up.
Use this site to host the pictures
Dave ----

 

(2nd attempt at posting images)

Does anything look odd to you here?

 

Can see it now.
Not odd if you want it to fill with fuel and sink to the bottom LOL

Did you say you got just the float or the whole unit?
Thought you can get just the float some where.
Dave - - - -

 

This was a whole new unit from LMC Truck, I think I paid like $80.00 for it. Came with the brass float.
They are being less than helpful on the customer service as well...will not send out a replacement. Instead they asked for pictures which they will send along and review. If then they deem that it is faulty, they will send me a replacement FLOAT in 5 to 7 business days. And, I'm sure it'll be a brass float, not made of some other material which may have a chance at lasting longer.

I did order a float off of Amazon as well, it was like 8 bucks and was made for a Jeep, but several of the comments said it worked fine on their old Ford trucks. So, I'll give that a shot and see how it works out.

Wish me luck...AGAIN!

 

I went with the plastic float that I got on Amazon for $8.00. It's for a jeep but fits perfect in my 85 F150


Such a relief...


Also...does anyone know what this second hose is that is attached to my fuel tank?
I believe it runs along the bottom of the cab and up the passenger side frame to the side of the carburetor.
The metal hose was totally rusted away and the rubber hose here was completely rotted. So, I plugged this end and the other which leads into the carb.
Does anybody know if it's actually needed?