Electrical Mayhem, Help Needed

[crash-harris]

I will make sure at least one battery ground cable gets there if there are no ground cables there now. Thinking about getting some 2ga cables if those are missing and bolting them to the frame.

I decided that if I ever get bit by a radioactive insect, my superpower needs to be locating electrical shorts. Mechanics, easy. Electronics in aPO made rat nest, that makes me downright irrational.

 

[franklin2]

The block needs to be properly grounded and needs the largest grounds for the starter and the glowplugs, but you will have to run separate grounds from the engine block to the firewall. On the gas trucks there is usually a decent ground strap bolted to one of the bellhousing bolts, and then going up to the firewall sheetmetal.

I am not sure how they ground the frame on the diesels, on the gas trucks they usually stripped back some insulation in the middle of the large ground wire going to the block, and put a metal band around it and bolted it to the frame.

The frame needs to be purposely grounded also. Even if you ground the cab on the firewall, the cab is mounted in rubber body mounts, there is no way for that ground to get to the frame. Just like if you grounded the frame, there is no way for it to ground the cab.

 

[IDIoit]

you can never go wrong with too many grounds.
i ground....
battery to engine,
battery to fender
engine to frame
engine to cab
cab to frame.
hell i even grounded my heater core.

 

[typ4]

Franklin, on the pass side neg cable there is a 8 or 10 ga wire that runs right to a frame bolt.

Crash, if the po made a mess, best thing to do is cut all that added stuff out, start from scratch and see what doesnt work.Then repair as needed. MOST of the wiring issues people "go around" are easily fixed.

 

[crash-harris]

Franklin, on the pass side neg cable there is a 8 or 10 ga wire that runs right to a frame bolt.

Crash, if the po made a mess, best thing to do is cut all that added stuff out, start from scratch and see what doesnt work.Then repair as needed. MOST of the wiring issues people "go around" are easily fixed.

The battery cables that are on it were put on by a PO before the guy I got it from had it. They are really simple and thick, not a mess, but I did notice that the passenger side cable was not grounded to the crossmember on its way to the starter like my gas truck. But I think a lack of pepper grounding is in play here. A few times the starter has acted similar to my gas truck, which needs new ground cables from battery to starter bad (corroded all the way down). I don't see any big, dark clouds out at the moment, so when I'm able to limber up from the morning muscles, I will be out taking pics and poking about to find this short.

 

[madpogue]

The starter is grounded through its mounting. There is no starter ground wire. The battery negative cables ground to the engine block, as mentioned above.

 

[crash-harris]

The starter is grounded through its mounting. There is no starter ground wire. The battery negative cables ground to the engine block, as mentioned above.

The gas trucks have a negative battery cable that runs from the battery to the engine crossmember, to the bottom starter bolt. On my IDI, the starter solonoid has 2 posts and each of those has a cable on it. Didn't have time to track it, but was assuming that one was a ground.

 

[cpdenton]

The gas trucks have a negative battery cable that runs from the battery to the engine crossmember, to the bottom starter bolt. On my IDI, the starter solonoid has 2 posts and each of those has a cable on it. Didn't have time to track it, but was assuming that one was a ground.

One heavy gauge wire that has straight from the battery, and one much smaller signal wire that goes up to the solenoid mounted on the fender. Those are the two wires you will have on your starter.
The fender mounted solenoid will have one wire, 8 gauge or so, coming directly from the passenger side battery. On that lug of the solenoid will be several fusible links that go off to power the chassis electrical and the glow plugs. Alternator charge wire should also attach here. Directly across from that past on the fender solenoid will be the smaller wire that goes down to the trigger wire on the starter mounted solenoid.

There will also be a small signal wire from the key on the fender mounted solenoid.


Grounds.

Your drivers side battery should have the one heavy gauge wire that goes down to the engine just below the harmonic balancer on the drivers side of the front of the block. It will also have a smaller gauge wire from the negative battery post over to the radiator support. That is your cab ground wire.
The passenger side came will have a large wire going down to the passenger side of the front of the block just below the harmonic balancer. At that connection point(large ring terminal), there will be a smaller gauge wire that goes from the engine ground over to a green bolt on the engine crossmember. This is your frame ground.

Both have to be clean and well connected or trouble will follow you.

Good luck!

 

[crash-harris]

Confirmed that those 2 grounds are missing. My passenger battery ground goes to the outside of the passenger frame rail in the wheel week worth a short cable from that to the engine crossmember. Driver side battery is just grounded to the power steering pump bracket. This is something I will address.

I ran a 14ga jumper in place of the fusible link that burnt and left both positive cables OFF the batteries. I get about 14 ohms between the core support and the positive connector for the passenger battery cable.

I have also confirmed that the fusible link that burnt is the same wire that I had issues with on the gasser truck (same year). It runs into the corregated tubing that runs around the core support to the drivers fender. Found 4 wires that look like they once had a harness on the end that are bare. Pulled them away from anything before probing with the multimeter.

Also going to pickup a new headlight switch connector. This one has the usual burn/melt, but the switch looks to be very new. None of the connectors are touching, but someone replace one with a standard spade connector in the most melted part of the switch.

Wires in question on drivers side fender

You must be registered for see images attach

You must be registered for see images attach

Found this when I pulled the headlight and wiper switch out. What is it? I've never seen it before, but guessing it's actually bolted down on the gasser truck.

You must be registered for see images attach

 

[crash-harris]

Anything on those 4 cut off wires? Some of them seem to go to this relay socket

You must be registered for see images attach

Couldn't get anyone to tell me what the relay that plus into that is for.

Also completely cut out the switch that was wired up to loose plus on the drivers fender and pulled the unsecured wiring for it too. It was the nasty looking bit on the right.

You must be registered for see images attach

 

[franklin2]

I thought most of your problems were grounding, but if you are messing around with all that other wiring and are afraid of melting more wires, the best thing for you to do is get a small 10 amp battery charger and plug it in your house and hook it to the battery cables for testing(leave the main batteries disconnected). Of course you can't crank the engine with it, but you can test all your smaller wiring and smaller loads like lighting, radio, domelights, etc. and if there is a problem, the battery charger has a circuit breaker inside that will trip and keep from melting and smoking any wiring till you get it all worked out.

Of course this small charger will not be able to handle the glowplugs either, so you could disconnect all 8 of them, or find the feed wire for the controller and take it off momentarily till you get all the other wiring worked out.

 

[fsmyth]

Jumping in here kind of late. Grounding definitely is an issue. Started to post that as soon
as I read your original post, but went ahead and read thru til now.
There have been some excellent suggestions and some off-the-wall.
Step 1. Ground your engine to the frame. At LEAST once. I CANNOT be too big.
Step 2. Ground your batteries to the frame. Same deal. The shorter, the better.
Step 3. With charged batteries, the truck should crank normally. It may not start.
Step 4. Troubleshoot all the dash instruments that were probably ruined by ungrounded cranking.
Step 5. Same with all the lighting (although these are a bit more robust, and probably were not
activated when you had the event).
Just ONE starter activation is enough to melt any active wiring (ignition/accessory/lighting) if the
starter has to get it's ground through them. And toast any appliance/gauge it has to transit.
Lamps are generally not harmed. Relays are. Switches are. Fuses are. Wiring is.
Some of that may be time-consuming to track down - it seems that wires like to burn in the
hardest possible spot to get to :_)
<als>

Also - the truck is one of the few that run grounding circuits through the keyswitch. I would
replace that first - they cost very little.

 

[crash-harris]

- it seems that wires like to burn in the
hardest possible spot to get to :_)

This.

I get absolutely no cranking. Can't get there. Connected the batteries this evening with the 14ga jumper wire in place of the fusible link that burnt and turn the key to on. The power is now kicking on and off at a fast, constant rate as heard by the GP solonoid. Only left it on for a moment, then disconnected the batteries again. I searched through everything on that drivers side fender and the only thing I found are what's in the pictures.

 

[crash-harris]

Dug up the bids and pieces of the old Red Dead Haynes manual. I now have eyes on the schematic I need. Thankfully, I remembered correctly and even though it only covers gas engines, it does have schematics for diesel powered trucks. From what I'm seeing here, of the 2 yellow power feed wires from the starter relay, one is a 20ga fusible link and the other is the 18ga that burnt through on my rig. Schematic says it goes to fuse #1. Guess I'll be looking at that after we get back from autozone with new battery cables for proper ground straps and a headlight switch harness.

Not bad for a cell phone pic.

You must be registered for see images attach

If you click the image it should take you to my photobucket to see the full thing. Although you can see the start to the words "starter relay".

 

[franklin2]

Fuse #1 if it's connected to the yellow wire would be hot all the time. You only have a problem when you turn the keyswitch correct? I would not be looking at fuse #1. I would be poking around with my meter or testlight with the key on.

1st thing I would do is put my meter or testlight on that spot with the two yellow wires on the starter relay. I would turn the keyswitch on and see if I had solid power at that spot.