So the whole idea of electricity is it trying to get back to ground in a loop and it will take the shortest path always. On my truck I went from the Neg post to the back of the head and make sure there is no paint on there as that will not be a good path must be bare metal, Then from the head I went to the frame as you can't rely on the motor mounts as a good path, then the whole frame is now a good ground source, you will also have to jump across the steering wheel rag joint if it is rubber like mine(75 Frame), and also go from the frame to the bed is recommended, but I think from the mounting bolts as long as there is a good clean connecting you are ok.

So power goes out from your fuse block to the required load and then in the example of a headlight the ground is right at the light so mine is attached to the rad support. So that is why i recommend trying a wire from the neg post with and alligator clip, you could use a set of booster cables and then you know you have a "good" ground, and if it doesn't light up your grounding maybe ok and it maybe your power but you can at the very least eliminate the grounding.

Make sure the is no paint or non metal finish on the ground at the valve cover.

Hope this makes sense it's like breathing to me.lol

D

 

Will, dman added more, I use a curcuit tester like this Ford Truck Enthusiasts Forums - jowilker's Album: General photos - Picture rather than a fancy meter.

Take the lights to the battery, touch either the frame or neg wire (neg wire is because the light was mounted in cardboard that doesn't conduct elec) to the - post and the hot wire to the + post. If it doesn't lite then the problem is in the light itself.

Think about it, there are only 3 wires going to the rear of the truck for the tail lights. 1 each for turn signal & brakes, the other for tail & license plate lights. Nothing for return except chassis.

As noted paint is the biggest blocker of current flow.






John

 

I really appreciate the help and good information you guys!

I overcame my fear of being bitten and tried this last night right at the battery posts and neither dome light would work. My multimeter says the battery is outputting 12.5v. The dome lights are so simple and both are in good condition. I find it hard to believe both are bad.

I don't have any other 12v gizmos lying around to test so here's my plan. I've got a job interview this morning and after that beat down I'm going to stop at the hardware store and pick up some suitable ground straps or 10 gauge or better wire. I will try those on later today.

I want to get the headlight switch out. I want to check the circuit breaker/fuse. When I pull out the bar there is like a key slot visible. I unsuccessfully tried to turn it. Anybody know how to disassemble it the rest of the way?

Thanks!
Will

 

Will 12v DC don't bite at all, a highly charged and ramped up spark plug spark can but we don't recommend doing that.

Check the bulb socket, I'd say it is unusual to have two dome lights not to work. Are you sure you had it grounded. I suggest getting a light tester like my photo link. Prolly less than $10.00.




John

 

On my F350, the engine (240CID) is grounded from the firewall to the bellhousing. There should be a grounding strap on the driver's side, top bellhousing-to-engine-bolt. The grounding strap is about 6 inches long and runs straight to the firewall.

Since the battery on the F350 is under the floor, I can't help you with the location of the negative terminal to frame ground. Mine goes directly to the frame, not the engine.

BTW my truck also has a CIGAR LTR 14A fuse in the fuse block which is pictures in the Ford Shop Manual.

 

Will- to remove the light switch from the dash you push the button on the top side of the light switch behind the dash and the the handle pulls out of the socket , which i think you are calling the bar. then on the front side of the light switch there is kinda a nut that is threaded into the light switch. it should have two notches in it and you can remove it with a wide screwdriver.it may be a bit tough to get off if it is still on from the factory install. rust and dust yano. LOL. Dutch

 

Im going down there tomorrow to work on it...the original ground from engine to cab was smaller then Im used to seeing on those with FE's Im so accustomed to...but I have some ground cables kicking around. The battery cable is about 6 inches too short to reach any sound place on the block for a solid ground. I also have all of the other possible things that may be the culprit ...including a parts harness to scavenge from :-)

Im just stumped why it would all of a sudden die ...weird indeed...more to come though...


- cs65

 

Thanks guys! I didn't get a lot done today but I did make it to the store. I bought some #6 wire and end pieces and made a couple of cheap ground straps. I put one on the firewall and bolted it to the bellhousing. I also moved the negative ground for the battery from the valve cover to the chassis. This should be an improvement.

Don and I will take a look at it tomorrow, and I will try to disassemble the headlight switch. We'll get to the bottom of this. Here are a couple pictures of the grounds:

 

My ground cable had an extra leg where it connected to the battery so I did a similar connection to the fender. Make sure you scrape away any paint under the connection.

Checking the dome light across the battery is the best test that you can do.




John

 

Hello everyone,

I've been preoccupied fixing up the front brakes with the help of Mr. Camperspecial65, and just now got around to working on the dead electrical issues. I hired an automotive electrical specialist (not me! ) from Thurston county who is doing side jobs, and it took him all of a half hour to find and fix the problem.

It seems one of the big multi-wire firewall connections seen in the pictures below contained a connector that had become broken or corroded. It effectively killed the whole truck electrically to put it into a few words. One picture is from outside and the other from inside the firewall after being temporarily fixed:




All systems are go now! I don't think we can buy these multi-wire plugs anywhere so sometime next week he will be returning and replacing both of these which are holding a dozen or more wires with custom plugs. It seems it's either that or get a new wiring harness which I really can't afford at this time.

I also need a new fuse block as mine is corroded to the point that the cigar-ette lighter and dome light wires came off in back. He is going to replace the original with an eight or ten slot modern fuse block which will get the truck ready for installing a radio, CD player etc. later on; I'm stoked!

He liked my ground cables I made, but I'm also going to buy a new longer negative battery cable with dual wires. The main ground will be attached to the engine block at the motor mount where some alternator grounds attach, and a secondary run to the fender wall.

BTW the dome light did work but the student electrician had his glasses on upside down or something that day hahaha!

 

Here are a couple of pictures of the custom plugs and new fuse block we (well, not so much me ) put in today. Everything has been tested and is working as it should. It took us about six hours to do the work and test everything, and didn't cost a fortune. Parts were about $125 including a custom long dual lead negative battery cable. I think it looks pretty good and you have to get up close to even notice the custom firewall connectors. One picture is from outside and the other from inside the firewall:



Did you know... that with certain wiring combinations you can get your left rear blinker and right front blinker to light when you signal for a turn? Yes you can! Probably not a good idea to leave it that way though.

I've got plenty of room now for radio, CD player and other gizmos. I also have an available circuit for future use in the engine compartment if ever needed. I've got the all clear now to put an interior in, but I will have to do a little painting here and there first.

 

That is awesome and great to hear! Good old electrician's to the rescue.lol It is nice to get that out of the way and know that you won't get stranded far away from home.

 

Yes that's true. My thanks again to everyone that pitched in; you guys are great! This was a tricky problem and I was spinning my wheels, so it was time to call in a specialist. I'm surprised I got such a great deal on parts and labor. It was worth every penny.