What happened here... glow plug resistor bypass?

[realm]

Can someone tell me what was done with the wiring here? I thought everything was wired as stock (except for a Ford glow plug relay the PO put in), but looking today I noticed the glow plug resistor bank has been totally cutoff and not in use.

My batteries are still wired in series for 24v it looks like, so how and where is my wiring powering the glowplugs if there is no bank to drop it down to 12 volts?

Pics attached.

Red wire across back of firewall goes to negative of rear battery.

 

[m38inmaine]

They are now running the glowplugs off the 12 volt block, this is using one battery to supply the voltage rather than two. Still works but puts a strain on the one battery.

 

[FMJ]

I wired my M1008 this way and used 60G (12V) glow plugs. Works fine, for almost 2 years now

 

[FMJ]

I wired my M1008 this way and used 60G (12V) glow plugs. Works fine, for almost 2 years now

oops, jimbo*'s 1008. . .

 

[realm]

Questions:

#1 If that's the case then is the starter the only part using 24volts on my whole truck now?

#2 What's the little relay looking thing to the left of the glow plug relay?

#3 So if you hookup X part to the positive of the 2nd battery then you're only getting 12 volts? Where is the 2nd battery grounded then?

#4 If I wanted to hookup say a 12volt portable air compressor, could I Just hook it to the postive of the 2nd battery and then the negative of the first battery, or where would I hook up the +/- connectors?

 

[FMJ]

#1 Yes

#2 terminal block

#3 Pos terminal of rear batt is 24 volts

#4 hook to the positive teminal of the front batt and then to ground

 

[realm]

Got it... thank you!

I was going to keep it all stock, but seeing now that it's already been somewhat modified I'm out of luck, so maybe I'll convert starter to 12volts and do away with 24 altogether... maybe.

 

[FMJ]

Here you go:

http://www.roscommonequipmentcenter.com/news_notes/nn10.pdf

And here:
Click on project list, and then military vehicles
http://www.roscommonequipmentcenter.com/

 

[RockyM1028]

So if I wire mine just like the above Pics show I can install 12V glow plugs from any auto parts store?

 

[FMJ]

So if I wire mine just like the above Pics show I can install 12V glow plugs from any auto parts store?

Yes, I did it, and it works fine.

 

[realm]

Wait... someone explain this to me...

If the military glow plugs are 24volt, then why is there a resistor bank that I thought drops it down to 12volts? Wouldn't that mean the original glow plugs should be 12volt?

So since mine is wired like this, the glow plugs it has are probably standard 12volt plugs?

 

[doghead]

The original military issued CUCV glow plugs, are 12v. The 2 big resistors drop the voltage from 24v to 12v, as soon as there is a load(the the gp's). When all 8 glow plug are working, the combination of their resistance and the 2 big resistors on the firewall, drop the voltage to the correct 12V level. When a glow plug goes bad, that changes the total resistance(load) and the final voltage does not drop low enough(12V), that is what causes the rest of the glow plugs to burn out.

Removing the resistors and changing the supply wire to the front battery for 12 volts(instead of 24V from both batteries), will eliminate the problem described above but.....
You will now draw a large load(when the GPs are cycling) on the one battery You will then have unbalanced voltage(When cranking) on the 2 batteries, causing a strain on the front battery and higher amps on the starter and starter relay and solenoid(also lower total voltage to the starter).

 

[84cucv1ton]

i do that to every truck i get

 

[doghead]

i do that to every truck i get

From your experience with this modification, what have you seen?

How many trucks?
How long have you owned them and operated them this way?
How many starts?
How cold are your coldest weather starts?


Have you experienced any battery failures?
Starter failures?
Starter solenoid failures?
Starter relay failures?
GP failures?


Have you posted this modification and suggested it to everyone? Have others here done this and had positive(only) results?

 

[FMJ]

opcorn:

 

[SSander]

I have exact same setup as in post nr.1 But im still getting 24v to my glow plugs.What did i do wrong?

 

[cucvrus]

You have the resistors bypassed and are getting 24 volts?

 

[SSander]

thats right,yes

 

[cucvrus]

Not sure. Are you tapping into the 12 volt power point on the left side of the firewall to the right of the brake booster. 2 studs. A 10/24 thread and a 1/4" x 20 threaded stud. Tap the 1/4". Not the stock way but I see it done. Should be 12 volt. That is where the entire 12 volt part of the truck gets its power.

 

[MarcusOReallyus]

I have exact same setup as in post nr.1 But im still getting 24v to my glow plugs.What did i do wrong?

Nope. You made a mistake somewhere. Post some pics of where you connected that you think should be 12v.