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Truck won't start-Grounds!

I think your right track with the melted wires. the relay getting power in run not just start makes me wonder. does the relay get power in run when the truck is forward/reverse? just trying to take things outta the equation.
 
keep us posted. we like to know the outcomes.

if you have a way to check the current, let us know what you found. little things sometimes are the key.:thumbsup:
 
I went outside to get my stuff ready for work tomorrow and while I was out there I stuck my DMM where the 10a crank fuse would go in the fuse block in the dash. When the key is in RUN, there is no voltage. When the key is in START, there are 12v. So from the ignition switch to the fuse block, it's working correctly.
 
Have you tried jumper wiring the starter to see if the vehicle will start with the key in the run position?

Hook a wire to a - held in for on - push button from the small terminal on the starter and to an "inline fused" 12 volt power source.

turn the key to on and after the glow plugs cycle push the button to run the starter.

For testing purposes - you can disconnect that wire from the starter and put 12 volts to it and see what that changes if anything in your relay.
 
the big question is why it won't crank by the switch with the relay in place. I'd still check the amount of current you have at the relay. something is not adding up here:rolleyes5:
 
juddspaintballs said:
That would be exactly the same as putting 12v to pin 87 at the fuse relay center. I've done that.
Click to expand...

Did the truck crank over when you did that?

It is not the same - you are bypassing wiring and jumping the starter. You will find out if the truck will start and run with the key in the on position.

Is that what happened when you jumpered the pin?

When you jumpered the pin did you have power at the starter?

If you put power on the small wire at the starter while it is disconnected then you should have power at the other end of that wire as well.

I guess I missed where you jumpered things and got the vehicle running - bypassing the relay and ignition switch

You can also test the little wire to ground while it is disconnected. If it has conntinuity to ground while disconnected that may indicate a short
 
I put 12v to pin 87, which is just the other end of the wire that leads to the solenoid on the starter. That spins the starter and cranks the motor but even with the key in the RUN position, the vehicle doesn't actually run. I suspect it has a lot to do with too much fuel being dumped in after all of these attempts to start the vehicle since every other ignition switched function of the vehicle works as it should.
 
juddspaintballs said:
I put 12v to pin 87, which is just the other end of the wire that leads to the solenoid on the starter. That spins the starter and cranks the motor but even with the key in the RUN position, the vehicle doesn't actually run. I suspect it has a lot to do with too much fuel being dumped in after all of these attempts to start the vehicle since every other ignition switched function of the vehicle works as it should.
Click to expand...

Did you have the vehicle plugged in?

Did you cycle the glow plugs before you jumpered the engine to turn it over the same timing as if you were using the key to start?
 
I just took the wiring harness off of the neutral safety switch. With the key in RUN, I have no power to the purple or the purple/white wire. With the key in START, I have 12v to the purple wire.

Everything works properly from the ignition switch up to that point. Clearly the problem is now between the neutral safety switch and the fuse relay center.
 
I didn't know how to check it, but before you had the chance to ask I thought the same thing and ordered a new one from Advance Auto Parts. They had a sale going on today, so it was under $30 with tax. I just got it installed and was about to go try it out. Came inside for the mechanic's helper, who just got in the shower so it looks like I'm on my own.
 
New neutral safety switch didn't solve the problem. Now I know it's in the wiring somewhere.

AK Diesel, on page 3 you gave me some copied pages. I can't make out the diagram at all. I can read the other 3 pages well enough. On the 2nd page of the step-by-step on solving the problem in step #4 it tells me to use a self-powered test lamp to check for continuity between starter relay socket cavity A7 and ground. I don't know which pin in the relay socket cavity would be A7. I figured out that B7 means the purple wire going to the starter solenoid, but I don't KNOW for sure what A7 is. I think it means pin 85 on the black wire that goes to ground.
 
I just popped apart my fuse/relay center to see what wires go to what pins on the starter relay.

PURPLE goes to pin 87 (AKA B7) on the relay. This goes to the starter solenoid. It has continuity to ground, but when 12v are applied to it, it spins the starter.
PURPLE/WHITE goes to pin 85 (AKA B9) on the relay. This is different than we thought. Purple/White should from the neutral safety switch with 12v when the key is in START. It doesn't show 12v when the key is in START.
RED goes to pin 30 (AKA A9) with constant 12v. This is correct.
BLACK goes to pin 86 (AKA A7) on the relay. This should be my ground. It's giving me 12v when the key is in RUN or START and has poor continuity to ground. 475 Ohms resistance to be exact.


That's all I have time for tonight. Work tomorrow, back at it Sunday.
 
To bypass a neutral safety switch you should be able to jumper the 2 wires together. Most that I have seen are normally open. If it's a single wire switch I would have to find out how it worked
 
IT WORKS!!

SUCCESS!

After finally confirming EXACTLY which pin was which at the relay, only then was I fully able to understand where the problem was. We had pin 85 and 86 confused most of the time. Pin 86 is actually my ground as confirmed by the black wire going to that socket in the fuse relay center. I followed the steps that AK Diesel Driver posted on page 3 (and emailed me the larger versions so I could read it) and one of the early steps was to check continuity on the socket for the black wire (labeled A7 in the diagram) with ground. I tested it with a simple audible continuity tester and got nothing so I switched to Ohm reading and got 475 Ohms between that socket and battery ground (474 Ohms to the intake where it should ground). On a hunch I decided to put a wire around that pin on the relay and stuff it into the socket and take that wire directly to the battery. It started in about 2 seconds of cranking. I'm not taking it out anywhere yet, but that confirms that the ground is bad and now I know how to fix it...on Sunday.
 
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