Electrical Mayhem, Help Needed

[crash-harris]

So I have a no start due to electrical. Went to start yesterday to go to work and everything was normal until a few cranks into starting. Everything cut out like there was a loose battery cable. I checked and ensured that all cables were tight and tried again. Normal WTS, then turned the key to start and got a pop under the dash that sounded like a fuse and the strarter relay would only cycle rapidly. Now when I turn the key to on, the GP controller just cycles rapidly, but intermittently, the dome light goes out and flips on with the GP clicking and if I leave the key on for a few more seconds I get back feed through the electrical and the fog lights and lighted switch to manually operate the reverse lights (to signal a successful lane change) turn on dimly without the switch on.

I've taken the dash and steering column apart, all fuses check out ok, no frayed or burnt wires, double checked battery connections down to the starter. Solonoid on the starter looks burnt. I have no idea what has caused this. Could the starter have taken a dump and be crossing positive and negative internally and back feeding without turning? Could the GP controller be the thing that crapped out and is causing the grounding issue? Internal failure in the fender mounted starter relay?

Ideas? Any help is appreciated. I've got to get this thing back up and running asap.

 

[crash-harris]

Just found what looks to be a burnt fusible link next to the passengers side battery. Had this same thing happen with Bruiser the first time the EEC-IV died. I've never been able to find the correct replacements. But I did try tying it back together just to test it and still have the same symptoms. Definitely not happy about this find.

You must be registered for see images attach

 

[laserjock]

Keep digging. Something caused that fusible link to burn. Start unhooking things and try to isolate it. Unhook the starter and see if everything else behaves properly again. Same for the alternator. Sure sounds like something is dead shorted to ground somewhere. Does your accessory setting work on the key switch? That looks like a fairly sizeable link there. It seems like it would have to be something pulling a lot of juice. Check your engine harness connector too. I find it odd that the GP controller is somehow acting on the dome light. It could be that it is the culprit too I suppose. Again, unhook it and see if things behave (besides you dont' have gp's obviously).

That's how I would start wading through it.

 

[crash-harris]

I disconnected the larger yellow wire from the GP controller and clicking became steady. It seems almost like there is a relay somewhere that is flipping due to a ground. Like it gets hot, disconnects, then reconnects quickly. The GP controller seems to be trying to kick on normally, then the power starts connecting/disconnecting and it's just trying to turn on normally everytime. Dash warning lights cone on and off with the dome light and the clicking.

The fusible link is a 20ga link, one of the smaller ones. I will disconnect the starter tomorrow if it's not pouring rain and try again as well s disconnecting the GP controller completely.

Everything works normally with the key in the accessory position.

Got sparks when putting the air cleaner back on. Didn't think the power to the GP controller was supposed to be constant with the key off.

I did pull the WIF sensor wire off the ground wire for the alternator and found that the taped off wire on top of the alt was suppose to go there...

Pics from my introduction thread

You must be registered for see images attach

You must be registered for see images attach

 

[laserjock]

The power wire to the GP controller is hot all the time. Sounds like your chassis is hot. Gp controller actuates when it sees power. If the chassis is hot, the controller is essentially seeing 0 volts so that may be why it's continuing to cycle. I'd unhook the batteries before it burns down. You said it popped under the dash. I'd pull the headlight switch out and look at it. They are notorious.

 

[franklin2]

I think the clicking may be coming from a poor connection over at the solenoid on the inner fender or a poor connection/bad battery cable. If there is no load through this connection, the whole system voltage goes up to 12v. When the glowplug controller gets the proper voltage it's like turning it on, and it says "ok lets glow the plugs". As soon as it closes the glowplug relay a large load is placed on this poor connection wherever it is, and the whole electrical system dies, the glowplug controller goes back to sleep and disengages the glowplug relay. As soon as it turns off the glowplug relay the heavy load through the bad spot goes away, the voltage in the system rises back close to 12, the controller wakes up and then it starts all over again.

What I would do is get a diagram, get a voltmeter, and get the truck to where it's blinking up and down again. With it blinking take the meter and put it directly onto the battery posts. If you get a solid 12v with just a small variation, you know the battery is good. If the voltage is jumping up and down you know you have a battery problem.

If that's good, leave one probe on a battery post, but move the other probe to the battery cable connector. Same thing, is the voltage fairly steady or is it jumping up and down?

Move the other lead to the other cable clamp.

Move the negative lead over to the engine block. If it starts jumping, you know you have a bad ground to the engine block.

Follow the + cable over to the solenoid on the fender and put the meter on the solenoid terminal. Blinking means you have gone past the bad spot and it may be a connection or the cable.

Use the diagram to follow the power. It's obivous the yellow power wire that feeds the ignition switch and the fuse box is beyond the bad spot, since everything in the cab is going up and down. So keep poking around and see where you get steady voltage and where it lose it and it starts going up and down.

 

[crash-harris]

Batteries should be good, only a couple months old. Probing power wires with the multimeter is always first on the list, even though it sucks to do. Battery cables should also be good as they are the enormous, semi transparent, fine wire braided (then braided again and once more) cables. Ground are the same and no breaks/corrosion.

Things are only energized when the key is on. If the GP controller has a constant positive, then I was hitting it with the air cleaner. Going to attempt to disconnect the positive cable from the starter at 2am when I get home to rule that out. Then I'll get to do the rest when it stops raining.

 

[franklin2]

Don't assume anything is good. Look at the diagram, use the battery as a starting point. If you are good with electrical and want to start in the middle, that's fine too. For instance if you want to start at the solenoid + connection, you can. They use that as a distribution point for a lot of the truck's power, so if you do have good solid power there, then you might have to start poking the insulation on some of the wires running out from this point.

And don't forget about the ground thing. You can put the + lead on the battery, and start moving the negative lead around on different grounds. You can even put it on the frame of the fender solenoid, there are small ground wires everywhere.

 

[Andertusa]

Batteries should be good, only a couple months old.

Even if they were/are good, a few times of being fried with electrical crap, they will be another problem.

 

[crash-harris]

Good point. They are still under free replacement warrenty. They'll get checked. Going to try to pull the starter cables off and if that doesn't work, GP controller power, then start proving from the batteries out in the 30 mind I'll have between waking up and leaving tomorrow.

 

[icanfixall]

We have several conatant hot items on our idi engine. The glow plug controller. The alternator and the starter is constant hot. If you are a not believer use the multi meter on these items. Might also check the large engine wire harness on the passenger side fender well. Many times corrosion ruins this. Mostly its the 2 yellow wires in it that heat up cause of corrosion and melt the plug. Those are the glow plug controller. Many years ago the electrical industry found that running 2 wires feeding power to something is cheaper than running one wire that can handle the load. You see this on the high voltage conductors feeding 500,000 volts on those huge metal power lines running across the country. Along the I40 out in the desert here we can see a bundle of 3 conductors carrying this voltage

 

[franklin2]

I want to make sure to get this point across; You HAVE TO do these voltage checks with the truck doing the crazy blinking. If you just go out and start poking around with the meter with no load on the system at all, it will tell you nothing. You want to see the voltage dropping when the truck is doing it's crazy cycle thing.

It's the same with troubleshooting a starter circuit; You can poke around with a meter all day and get nowhere. You have to put your meter in the circuit, and then get someone to turn the keyswitch to start and then take a reading.

That's why they make those big battery checkers that when you hit the button, it puts the battery on that large resistor inside the unit and it can start smoking. They are checking the battery under load to see if it's any good.

 

[crash-harris]

In the 5 mins or less that it stopped raining, I started to probe with the multimeter and the key on. As soon as I got to the front of the truck, I heard a sizzle. The ground lead on the block heater plug has heating the water on the bumper where it was making contact and hot (not plugged in of course). Started raining again...

 

[madpogue]

Hmm, the block heater isn't part of the truck's electrical system. The ground conductor grounds to the engine, but there should never be any 12VDC current on the block heater cord.

 

[crash-harris]

Hmm, the block heater isn't part of the truck's electrical system. The ground conductor grounds to the engine, but there should never be any 12VDC current on the block heater cord.

Agreed. Couldn't get the cables off the starter or even the batteries for that matter before the rain started pelting me again. Had to leave anyway.