M1008 Dead No Electrical

[m38inmaine]

Trying to help out the local forestry get their M1008 back up for fire season. Driver said when he went to start it during the glow plug cycle he heard a snap or pop bang etc and everything went dead. I went over and checked the battery voltage 26+ volts, same at the glowplug relay, have 13+ at the firewall block. Nothing will turn on, I mean nothing, no lights no ignition nothing, as if the batteries were missing from the truck. I jumped the starter connection at the starter relay and it spins over fast and strong so I know the batteries are good and the starter system is ok. If you have the meter on the light fuse and are reading 13v and then turn on the lights the meter goes to 0. This usually means a bad ground but it's affecting the entire electrical system. Wondering if a bad or shorted alternator could cause this. All the grounds are solid. Hoping someone has had this happen before. I have been driving these things for 20+ years and never have seen this happen before.

Thanks

 

[Warthog]

Sound like the fusable link from the batteries to the 12v terminal block has mostly burned up. Sometime you can have voltage thru a bad wire but when you place it under load, it fails.

1. remove and clean the battery terminals. Also the 24v terminal block connections.
2. check the ground connections at the radiator support and engine.
3. give the fuable link at the 12v terminal block a tug, if it is soft and has movement it may need to be replaced.

 

[m38inmaine]

I will give that a try, thank you!

Mark

 

[m38inmaine]

Give that man a cigar! it was the fusible link for the 12v block feed. It would show 12v but carry no amperage. I have never had a fusible link go before, I thought there would be some sign of it being burnt so I assumed it was good since I had voltage. Thank you very much.

Mark

 

[Warthog]

Another satisfied customer.

See sometimes us old farts know what we are talking about... Another reason to have a stock system. From across the country, the problem could be diagnosed and fixed.

Good job on finding the problem.

 

[MakersTeleMark]

Good on you. Now, when these links go, what's the best replacement? I would think a breaker would work well.

 

[m38inmaine]

Well they do make replacement links but it's back to stock for this one from a donor truck in the boneyard. I keep all my trucks stock as well the ones I work on, as said before makes things easier to fix.

 

[Warthog]

Good on you. Now, when these links go, what's the best replacement? I would think a breaker would work well.

You can buy replacement fusible link wire at NAPA and other locations. It comes in different sizes.

The big black barrel connector is just a housing and is tough to replace. I just use a butt connector and some shrink tubing to replace it.

Try to kept the length of fusible link wire the same as you are replacing.

There are many Youtube videos showing how to do it.