GP Resistor bypass

[CycleJay]

Hi Guys,

I keep reading about this GP resistor bypass,
but after searching a little bit.
Not really finding a clear answer.

So, what is it? and what is the point of it?

Thanks, Good night,

CJ

 

[cpf240]

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!

 

[CycleJay]

Hello Cpf,

Thanks for the information. I will keep that in mind.

Have a good night,

CJ

 

[Warthog]

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

That sums it up very well.

 

[CROM]

I just did this to my M1009 yesterday. It's easy, and saves your glow plugs. You can connect the top post of your gp relay to the 12v bus on the firewall right next to it and throw those resistors in the garbage in about 10 minutes!

 

[wired1000]

I will have to give this a shot! Thanks for asking this question CycleJay!