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Running lights/stop lights don't work, headlights functioning

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jbritt

Running lights/stop lights don't work, headlights functioning

This is post replacing the fried headlight wires, leaving it apart for several months, oh and not taking any pictures before tearing into it....

86 f250 single cab long bed with dome lights

So, I have hi and lo beams, parking brake light, 4x4 light, and nothing else.
The following pictures are how the switch is currently wired.

the white wire coming from the A pin is the headlight wire that was burnt.
I have tried to work my way through three different wiring diagrams and still cant crack this one. It looks as though the power for the brake lights comes through the turn signal/hazard switch ut i have been unable to get power to the circuit.
Now the White wire with the blue connector was the other burnt wire that i would which i replaced the bad section of. It is hot at all times and I do not know what it goes to/is for. Below is the connector that is on the other end,

it is the black wire with electrical tape that connects to the same terminal as the brown wire.

last little thing is the black wire coming from just above the hi beam switch. when I apply voltage the dome lights kick on. just wondering how that ties into the wiring so it is part of the switch circuit.

I know theres enough knowledge on this site to answer my questions, I just hope the right people see this!
Thank you kindly in advance for any help of tips!

Regards,
John

Keaton
'86 F250 XL 6.9 idi with a sidewinder, zf5, 4x4, single cab lb

ArdWrknTrk

Re: Running lights/stop lights don't work, headlights functioning

Administrator

This post was updated on .

I would start with the '86 EVTM available in the resources section of this forum.

It details the Electrical & Vacuum Troubleshooting of your specific vehicle circuit by circuit, connector by connector, and pin by pin.

Each circuit is broken out individually, and all test procedure is detailed.

I hate to say RTM!, but please rtm...

Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.

Gary Lewis

Re: Running lights/stop lights don't work, headlights functioning

Administrator

In reply to this post by jbritt

Let's take this one step at a time. First, the EVTM Jim referred to is here: Documentation/Electrical/EVTM's/1986 EVTM. And there are several sections you'll need, like Charge & Power Distribution - Diesel Engines; Headlamps; and Stop, Turn, & Hazard Lamps.

The reason the truck had problems in the first place is the marginally-adequate-when-new design of the headlights circuit. It had all of the power to the headlights going through a skinny, barely adequate, wire to the switch and then out to the headlights. You might want to read the page here to see how to ensure that doesn't happen again: Documentation/Electrical/Lighting/Headlight Wiring Harness.

Now to the problems. Let's start with your first statement: "I have hi and lo beams, parking brake light, 4x4 light, and nothing else." Does that mean nothing else in the truck works? Or nothing else in the lighting? I ask because when diagnosing you have to know what the symptoms are and making assumptions leads to chasing rabbits.

As for the white wire, is it a replacement for an original wire? If so, what wire does it connect to?

Let's leave it there and pick things up after your response.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

jbritt

Re: Running lights/stop lights don't work, headlights functioning

This post was updated on .

In reply to this post by ArdWrknTrk

I will take a look through that today and see where I get with it. I figured there was a rock I hadn't turned over yet documentation wise.

and as much as we hate to say it some times, it helps to reminded to rtm from time to time, so thank you for that.

Keaton
'86 F250 XL 6.9 idi with a sidewinder, zf5, 4x4, single cab lb

jbritt

Re: Running lights/stop lights don't work, headlights functioning

In reply to this post by Gary Lewis

Awesome, gonna read up on the evtm and how to prevent the meltdown today!

As for what i have and dont have, that is in reference to just the lights. To word it better, I have hi and lo beams, all dash lights function except for the gauge illumination/dimmer, and my dome light does not work. otherwise, the truck runs and drives fine (knocks on wood).

The white wire is a replacement wire that I put in to replace a section of burnt wire I found. It is the taped black wire indicated with the red arrows:

The grey connector is on the drivers side of the vehicle, on the firewall in the engine compartment below the brake master.

Keaton
'86 F250 XL 6.9 idi with a sidewinder, zf5, 4x4, single cab lb

jbritt

Re: Running lights/stop lights don't work, headlights functioning

this was last week (dash has since been put back in) so I wouldn't be surprised if theres a ground missing. Bout to dive in on it with the new info, I will check back in after a bit of digging and let you guys know if i find anything.

Keaton
'86 F250 XL 6.9 idi with a sidewinder, zf5, 4x4, single cab lb

Gary Lewis

Re: Running lights/stop lights don't work, headlights functioning

Administrator

That can really be intimidating. So feel free to ask questions.

And a black wire is almost always a ground.

Gary, AKA "Gary fellow": Profile

jbritt

Re: Running lights/stop lights don't work, headlights functioning

This post was updated on .

so it looks like I'm missing the two brown wires coming from the R pin on the light switch. this would explain the lack of cab lights, as well as the marker lights.
Going to try and trace wires from the marker lights back to the switch in hopes of finding the missing connection.

The diagram shows a brown wire going to c906 as well as g909 next to it. I have a brown wire but it has a light blue tracer... are they one in the same? I also am not seeing a ground where g909 is supposed to be.

Keaton
'86 F250 XL 6.9 idi with a sidewinder, zf5, 4x4, single cab lb

Gary Lewis

Re: Running lights/stop lights don't work, headlights functioning

Administrator

Ah, you discovered those pages and edited your post.

Yes, lack of that wire would explain several things.

Tracing isn't easy, but you do have a large part of the cab apart, so maybe you can. Good luck!

Gary, AKA "Gary fellow": Profile

jbritt

Re: Running lights/stop lights don't work, headlights functioning

Im thinking that i just cant see where it is on the diagrams but I cant seem to locate the junction block. Is it the fuse block?

Keaton
'86 F250 XL 6.9 idi with a sidewinder, zf5, 4x4, single cab lb

Gary Lewis

Re: Running lights/stop lights don't work, headlights functioning

Administrator

Many of the connectors and all (most?) of the grounds are shown on the Grounds page toward the top of the EVTM's index. I t shows G909 at "Lower LH Cowl access hole" and is shown on Page 75 and depiction 7, which is in the Exterior Lights section.

Gary, AKA "Gary fellow": Profile