Military Vehicle Repair: M1010 to 12 volt conversion, m1010, military spec

Question
Hello Van. I read your other post recommending not to change over to a 12 volt system - just curious as to why not? I have a 1984 M1010 with the 24 volt alternators. From my understanding, the second alt. was for power to the ambulance compartment. In my case the area has been stripped with nothing but the relays left over the wheel well and the ceiling light. My motivation for changing over is the voltage regulator? (smaller of the two units on the left fender) is fried along with some of the inline diodes (I am not sure if the diodes are OEM as they appear to be a "custom" fix from some point previously). My thinking is it would be easier to change a starter and replace an alternator (which I already have from a blown motor 12v Chevy) than hope replacing the regulator is the real problem and not just a symptom of another problem. An ironic thing is everything except the glow plugs still works as normal with the regulator completely disconnected. Any advice and opinions are greatly appreciated. Thanks for your time.

Answer
Hello Tom,

I believe I said not to switch...unless you had the 1010.

Yours would definately be cost prohibitave to try to restore to military spec.

On the left fender, there is a regulator, and an isolator. BOTH are very expensive, so I would also be looking at converting.

I actually have now, and have had several 1008's.
Then I aquired three 1010's.

Only one of the 1010"s is still orriginal.

But the other two, I didn't convert to 12 volt, but rather, converted them to the same as the 1008"s, because I use the 24 volts quite a bit with my fleet and equipment, and thoroughly understand the 1008 system.

To convert shouldn't be all that hard. Everything on the basic truck is 12 volt, except for a relay under the dash to operate the 24 volt starter, and a relay for the volt meter.
There is a 24 volt fuse socket also.

Those inline diodes are on all of them by the way. Seem to be wired in as "clamping" diodes to protect electronic circuits from spikes.

That relay for the starter is screwed to the underside of the dash, about where the ash tray is.
If you measure voltage before you teat stuff loose, you will find one wire that operates the relay when the switch is turned to crank. it will be 12 volts. Across from it is a wire to ground.

Of the other two wires, one is 24 volt supply, and the other goes to the starter solenoid.

Probably about as easy as cutting all four wires, and then splicing the one from the switch, to the one to the starter, and you will have your 12 volt start wire to the new 12 volt starter.

Unhook the red cable from the firewall terminal block, and paralell the batteries, and you should be in business after the alternator swap.

You may need to run some ignition sense to the alternator for orriginal excitement, and install a 12 volt gauge. I'm not sure the charge lights even have bulbe in the 1010.

I would love to hear how you come out, or if you find a simpler method.

I am    richard_vannatta@sbcglobal.net

I have manuals for the truck, so if you have any other questions, drop a line.

Van