M1028 Cummins swap

[Ithaqua]

I am putting a Cummins in my truck after the me and the 6.2 mutually decided to part ways. Also a NV4500 is going in because I have issues. We came across something during disassembly I am hoping someone here can ID. It wasn't hooked up to anything and we would like to know what it was supposed to do.

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Thanks.

 

[Rutjes]

Glow plug resitors. This guy explains it well:

The stock system supplies 24v to the GP relay. Using the combination of the large resistors on the firewall and the resistance of all the GPs, that 24v is dropped to about 12v at the GPs. The GPs in the CUCV are not rated for 24v, thus the resistor dance to drop the voltage to a level they can use.

If / when a GP goes bad, its resistance is no longer part of the equation, thus increasing the voltage supplied to the remaining GPs. More voltage to the GPs means they burn out faster. As each GP fails, the remaining GPs see more and more voltage, which leads to a "cascade failure" of the remaining GPs. This may also contribute to the swollen tip problems seen with the GPs in the CUCVs.

By disconnecting the 24v wire from the supply side of the GP relay, and supplying the GP relay with 12v instead, you are extending the life of the GPs.

The only downside appears to be a reduction in the effectiveness of a jump start via a NATO slave cable.

I think I have that right, and if not, I'm sure I'll be corrected!

Mine was already bypassed as well. I think most people do this.

Good luck with the swap!

 

[Ithaqua]

Thanks!

 

[Karl kostman]

THATS A CHANGE i COULD never ARGUE WITH, when ever I drove anything with that engine in it I could never get past the word PIG in my mind, noisy and gutless is what I remember most!
KK