Electrical Mayhem, Help Needed

[crash-harris]

Yet it is now very obvious that there is no grounding going on with the ignition off.

 

[crash-harris]

Just ordered a Haynes diesel manual. To bad my free junkyard found shop manual doesn't extend to the correct generation that I'm working with. Hoping that I will find the culprit before it arrives.

Saturday we are scouting a wedding venue since it's going to rain more, then Sunday I'll start tracing the circuit from the fusible link that fried. It was the smallest of the 3 yellow power wires that supply all the circuits. With any luck I'll find it on top of the drivers side fender and can repair it.

 

[cpdenton]

What year model is this truck? I see some info on it, but missed the year model. That Haynes diesel manual probably won't have a whole lot of info on electrical wiring. You need to get the correct year f150-f350 electrical vacuum troubleshooting manual, or EVTM for short. That is published by ford for each year model. It has all the wiring information you could ever need. Colors, sizing, connection points, etc...

 

[crash-harris]

What year model is this truck? I see some info on it, but missed the year model. That Haynes diesel manual probably won't have a whole lot of info on electrical wiring. You need to get the correct year f150-f350 electrical vacuum troubleshooting manual, or EVTM for short. That is published by ford for each year model. It has all the wiring information you could ever need. Colors, sizing, connection points, etc...

Thank you for pointing that out. Edited my signature to reflect years. It's a 1990. Build month is October and the gasser was built in November, both of '89 for the '90 model year.

I do also have the discontinued red Haynes bible for gas engines. Won't help with vacuum but has wiring diagrams in it as well. IIRC, it also has references for diesel specific items in those diagrams.

 

[laserjock]

So something is shorted out to ground when the key is on. Look at your key on circuits. Off hand, that would go to the gp controller, the alternator, ip fuel shutoff. If it behaves on accessory, I doubt it's the radio or a window. It seems to me that if it's trying to find ground through the block heater, it's highly likely the culprit is attached to the engine. Check the red wire with green tracer. It's the key on power to the engine stuff if I remember right. Check the things that it connects to first. Check the gp harness carefully too along with the big connector on the pass side where the engine harness plugs in. That spot is notorious for corrosion.

My money is on the alternator or amongst the GP controller. If you heard a pop under the dash, the gp controller is close enough you could mistake it.

Happy hunting.

Whatever it is is shorted out all the time but it's not energized until the key on power is applied.

 

[crash-harris]

I would imagine that it probably has something to do with the alternator (worth the ground wire that's not connected on it), or the GP controller (with the PO before the last ones janky wired switch to turn the controller on via the wiring on the drivers fender).

The pop could have also been that fusible link going, though I know wires tend to smolder versus popping.

I did cut the wires out for the janky switch after this happened though. I nor the PO ever used it. 3G alternator is also in the plans. I hope this give me an excuse to do it now as I can get it setup for the cost of just the harness (lifetime warrenty on Bruiser's 3G).

And thank you for the wire colors. I seem to remember tracking that same one down on Bruiser before as well.

 

[LCAM-01XA]

Just ordered a Haynes diesel manual. To bad my free junkyard found shop manual doesn't extend to the correct generation that I'm working with.

Which year manual do you have? 80-86 and 87-91 trucks are nearly identical, same with 87-91 and 92-94 trucks in regard to the engine stuff...

In any case, what's the color of the wire on the other side of the burned fuse link? We do have a bricknose EVTM that will show the proper diagrams for your truck, but with several 20 gauge fuse links in there we need to narrow things down a bit.

Also, do yourself a favor and disconnect the batteries, NOW!!! If the bumper was getting hot where the block heater connector was touching it that means something is VERY wrong with your electrical system - I recall seeing this happen once before, IIRC it was on a different truck site, but someone had recently installed new batteries and for some reason one of them had switched polarity internally and was causing all sorts of havoc. So pull the cables off, check batteries one at a time, and if they prove good leave them disconnected till you can spend more time on this. More than one Ford truck has burned to the ground due to electrical issues and taken the garage and the house along, don't want that before your wedding, or ever.

 

[laserjock]

As a side thought, if the block heater is the most direct path to ground, your engine ground straps may not be as good as you think. There should be one on the lower pass front of the engine that goes over and clips to the frame if memory serves.

 

[snicklas]

...I recall seeing this happen once before, IIRC it was on a different truck site, but someone had recently installed new batteries and for some reason one of them had switched polarity internally and was causing all sorts of havoc...

LCAM,

I know for certain this can happen. It happened to Travis on E-2. The passenger side battery had switched polarity and nothing worked right. It cooked the GPC, and a few other things....... the WTS light just stay on all the time. We figured it out, jumpered a couple of things and got it running. Of course the day this happened it was about 20 degrees and snowing........

 

[crash-harris]

Which year manual do you have? 80-86 and 87-91 trucks are nearly identical, same with 87-91 and 92-94 trucks in regard to the engine stuff...

In any case, what's the color of the wire on the other side of the burned fuse link? We do have a bricknose EVTM that will show the proper diagrams for your truck, but with several 20 gauge fuse links in there we need to narrow things down a bit.

Also, do yourself a favor and disconnect the batteries, NOW!!! If the bumper was getting hot where the block heater connector was touching it that means something is VERY wrong with your electrical system - I recall seeing this happen once before, IIRC it was on a different truck site, but someone had recently installed new batteries and for some reason one of them had switched polarity internally and was causing all sorts of havoc. So pull the cables off, check batteries one at a time, and if they prove good leave them disconnected till you can spend more time on this. More than one Ford truck has burned to the ground due to electrical issues and taken the garage and the house along, don't want that before your wedding, or ever.

I have the old red cover manual. 80-95, f100-f350, including the lightning, all gas engines. So manual is the super manual. 65-85, gas and diesel.

Color of the wire on the starter relay side is yellow, the large one that has about 5 fusible links that split off it. The other side of the one that burnt through is also yellow. If you look at the picture I posted (should be able to click on it too if you need it bigger), you can see the other wires that come off the same large yellow supply wire and I the there is another yellow wire below the on that burnt through. Lots of diet and grime on it.

Batteries are disconnected just in case. Both holding at 12.75V.

 

[madpogue]

Have you LOAD tested the batteries?

 

[crash-harris]

Have you LOAD tested the batteries?

I don't really have any way to load test them. I did, however, turn the key and check them with the multimeter. 12.35~V.

 

[franklin2]

As a side thought, if the block heater is the most direct path to ground, your engine ground straps may not be as good as you think. There should be one on the lower pass front of the engine that goes over and clips to the frame if memory serves.

I am thinking this is the problem. You don't have a good ground to the frame/sheetmetal or somewhere else. You must have a good ground to the engine block, but the engine block is mounted in rubber engine mounts, as well as the tranny and the rearend. I wonder what would happen if you took a jumper cable and clipped it to the engine block or the negative of the battery, and clipped it to the firewall on a bolt or the fender or something.

The block heater was trying to complete the ground circuit through it's wire and the bumper. I bet that's why it was sparking and getting hot.

 

[crash-harris]

I will poke around and look for that as well. It looks like the reman Jasper 7.3L was a shade tree job with the ground on the alt case taped off and the what seemed to be econoline fuel injector lines. They may have neglected to replace engine grounds to the frame/body. One battery is grounded to the game and the other to the power steering pump bracket. Although it still seems that is only a contributing factor to whatever is now grounded with the ignition on.

 

[typ4]

If **** a suspect install look for pinched hot wires that now have just showed up.
The ground cables go to the bottom front of the block, both sides, 1/2 inch bolts IIRC. If you were close I would have that baby fixed in a couple hours. Electrical is one of my specialties.

The 2 red circles are the proper ground points for the battery cables.