Glow Plug Resistor Bypass
Very sweet ride. Want to sell it?
I recommend the bypass for civilian use. You can read a lot about the pros and cons if you search the CUCV forum. But, in short the military had to compromise on the design (what design isn't a set of compromises?) in order to allow a truck that might need to be started in a hurry to be jumped from a 24V NATO standard source. As was mentioned above, each GP that fails (they all eventually do) causes an increase in circuit voltage as the total load on the circuit is reduced. This causes the remaining GP's to see increased voltage, which is likely to hasten their demise.
If you do decide to perform the bypass, make sure to disconnect the negative cables on both batteries before starting work. Start with the front battery as that one is grounded to the vehicle frame. This is a must for pretty much all electrical repair work.
Some suggestions:
It is up to you as to whether or not you leave the resistor in place on the firewall. I chose to remove mine, and have them in storage in case I ever sell them to a "collector" that wants original. Keeping them in storage should slow down any further physical deterioration of the resistors. It also allowed me to treat the small amount of rust on the firewall while it was still surface rust.
If you leave the resistor mounted, I recommend removing the feed wire on the passenger side which connects to the 24 V buss. The feed wires are connected to the resistor by a very small stud/nut that can be removed. Some folks just cut the wire.
You can utilize the wire on the output side of the resistor. It should already be connected to the top of the relay. If you remove it from the resistor it is just the right size to connect up to the smaller stud on the diamond shaped junction just above the relay. This junction block is your 12 volt feed for the bulk of the truck. It is connected electrically to the positive terminal of the front battery, but physically to the negative terminal of the rear and passes through a fusible link running along the firewall.
While you are at it, clean ALL connections you can. Coat them with a small amount of dielectric grease to help reduce future corrosion. Make certain to clean as many grounds as you can!
Be prepared to replace the Glow Plug relay after the bypass. It seems fairly common that an old relay that has switched 24 volts cannot pass 12 volts well. My theory is that 24 volts causes increased arcing of the relay contacts. This creates additional deposits on the contacts which 24 volts can overcome.
Please let us know what you decide to do and how it turns out.
