M1009 Electrical Problems after Changing Glow Plugs

[avlon01]

Ran into a problem I can't seem to figure out.

Disconnected and removed batteries in order to access glow plugs on passenger side easier.

Changed all glow plugs on the M1009 with replacement AC Delco plugs.

Reconnected wires to glow plugs.

Reinstalled batteries.

Connected high ground.

When I went to connect the cable from the firewall to the positive, it sparked and started the cable on fire.

Checked all my connections on the glow plugs, all seems OK.

Truck was working fine beforehand and I had replaced the batteries last year and was driving it yesterday.

Any suggestions on why I am getting sparks and cannot connect the cable from the firewall?

Picts attached of my setup.

 

[Tow4]

Post a picture of the front battery.

 

[Freeland]

Hello avlon01,

If the cable that you hooked up to the positive side of the battery smoked or caught on fire, that means that that cable is going directly to ground/chassis. Try to describe any other areas that you may have disconnected any wiring that you may not have mentioned and take more pictures. Just like Tow4 asked, take a picture of your forward battery, but also take a picture of the glow plug solenoid attached to your firewall with the orange wires coming out of it. I'll go take some pictures of my M1008 batteries and cable orientation and re-post later today.

 

[avlon01]

It's raining like crazy right now, so no pictures yet, although it sparked as soon as the wire from the firewall touched the positive - this is before I had even hooked up the front battery.

As for any other disconnects, I obviously disconnected each glow plug spade connector and each of the batteries - no other connections were disconnected.

Front battery just has the cable that connects between the two batteries and the ground cables.

 

[dmetalmiki]

I would agree with the post that suggests the wires are not to the correct terminals.

 

[Freeland]

Here are some pictures of my M1008 battery cable configuration:

Good luck. Post more pics when it stops monsooning.


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[Freeland]

Oh, and in case you hadn't already noticed, the smaller cable that travels along the firewall gets hooked up to the aftward/rear battery negative (-) side if the battery, if you hook it up to the positive side, it will spark. You'll probably need to run over to your local auto parts store and purchase some fusable link. Just take the burnt up length with you as a reference.


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[avlon01]

Thanks for the help everyone.

I somehow managed to reverse the second battery and was putting the negative on the positive.

Reversed the battery and tried again with a new wire. No sparks. No fire. And now everything works.

Not sure how I managed that one!!!!!

Thanks!!!!

 

[o1951]

I know I said this before, will repeat for general information, and maybe stop someone from getting hurt..
Mark every wire you disconnect, even if you are sure you know where it goes.
To prevent wrecking wires or harness.
Don't try to connect to batteries directly. Put a test light between cable and battery post first. I use a brake lamp bulb or an old headlight where one filament burned out. If it lights up bright, then either some stuff in the truck got turned on, or something is hooked up wrong.
Quick, easy and saves lots of trouble.

24 volts is not like 12 volts. At same resistance, get 4 times the amperage. More than once, I have seen where the terminal got melted off a battery!!

 

[Freeland]

Great! I am glad to hear avlon01 that it's up and running again. Yeah... darn battery configuration in general on this vehicle and electrical system can get confusing quickly as the Military required a 24VDC starting system, so we have 2 12volters in series, and negative sides of batteries going to positive places, it gets ridiculous in some places in the engine bay. Every time one of my friends or someone sees under the hood of my truck they are flabbergasted 1 to hear that it's a diesel engine, and 2 when I tell them that it's a 24-volt starter but everything else runs on 12-volt, they just become confused from there. I work on airplanes, jets, and helicopters, so I'm used to dealing with 24-volt systems, but none of them are like the electrical systems that you and I have in our trucks! Haha!

Cheers man! That reminds me, I should probably go get a set of glow plugs and replace mine also!