Any one do the Roscommon 12volt conversion?

[math1960]

I just spent two days and a lot of money rebuilding two alternators and rebuilding the starter and converting to 12volt, and it's not working! Glow plugs not making any sounds. Got lights and wait light. And before the I told you so's begin It didn't work in 24 volt either. The starter and alternators were fried.
Any ideas? Thanks.

 

[BIG_RED]

Wiring? Switches? Relays? not to be a pain but i don't have much to go on.. What works?

 

[rickf]

Your not still running the glow plugs through the resistor bank are you? How are you running two alternators with 12 volt?

Rick

 

[math1960]

Red, The lights work, the wait light for the glow plugs work , the dash meter doesn't . I don't hear the glow plugs clicking nor any noise from the new starter. Not a mechanic, sorry.

Rickf, just one alternator per the Roscommon convertion in the resources section.
Thanks

 

[BIG_RED]

Didn't mean to be disrespectful, I apologize. I have respect for anyone brave enough to try to fix stuff on their own.

Is there power to the small wire on the starter when to turn the key to start? Is there power at the battery cable on the starter? Is there 12volts on one of the big terminals on the glowplug relay? Are both (or one?) batteries charged?

 

[rnd-motorsports]

I have converted several to 12 volt yes I use the same conversion. the volt gauge in the dash will need to be changed it is a 24 volt one you will need to install a 12 volt one, the glow plug risistor would have been removed when you converted I would check to see if you may have a wire fuse bad with ohm meter do you have power to the glow plug relay? on the fire wall ? if the wait light works then the controler should be good and working.If the starter was bad to start with and you had it rebuilt just asking did they rebuild it 24 volt? you will need a 12 volt starter I use the gear reduction 12 volt on any I do! have you checked the starter relay under the dash? with being converted to 12 volts you will not need it but I still use it but with the doghead conversion. if you do not use it you will need to join the purple with white strip and the purple wire together and cap the red wire as it will be hot the black wire is ground

 

[1956_4x4]

What does rewiring the relay under the dash accomplish? Just asking since this is something I don't remember doing a few years ago.

Smitty

 

[doghead]

When you convert to a 12 volt starter, you need to supply the solenoid with keyed 12v power(instead of 24v as it was originally).

In the stock 24v cucv. the under dash relay is converting/switching 12v keyed(start position) to 24 volt (start) to the 24v starter solenoid.

The purple with white trace wire is the original 12v keyed(start) wire.

The purple wire goes to the starter solenoid. It will need the 12v(purple with white wire) connected to it.

To add confusion, you could leave the relay under the dash and resupply the red wire with 12v. It's more simple to just eliminate the relay and connect the purple wire to the purple with white tracer(to activate a 12v starter. A simple jumper wire with 1/4 male blade terminals can do the job.


EDIT, be sure to read posts 9 and 10, the above information(post# is uneeded if you are using the RoscoCommons conversion instructions.

 

[rnd-motorsports]

doghead when you change underhood to 12 volt bye the roscommon conversion you already change the supply to the relay.Really need not do anything to it. Just the way you said it its sound like another step needed! sorry just adding I didnt try to add cunfusion here. But just becouse your doghead conversion is a great conversion with what its changing I still recommend it and do it to the ones I deal with just becouse the factory relay may still fail even at 12 volts and that is a good draw that the relay removes from the Ignition switch Its still a good deal even at 12 volts!! or just remove it as You and I stated and jump the wires needed! I like the idea so I leave it!

 

[doghead]

Thanks for the correction/information Ron.

I have not done the 12v conversion or read all the instruction over at Rosco Common.

I should have read it before posting what I thought needed to be done.

 

[Crash_AF]

The relay under the dash is only to isolate the 12V truck power from the 24V solenoid. In a 12V conversion it isn't needed so you can connect the purple and purple/white wires together to eliminate the relay and a potential point of failure in the system.

Did you replace the glow plug relay? Sounds like it's bad or hooked up wrong. The small orange wire must be hooked to the same large terminal as the glow plugs or the system will not function properly. The TM wiring diagram is wrong and shows this wire connected to the supply terminal on the relay. If it is connected this way, the light will come on, but the relay will not close.

Later,
Joe

 

[doghead]

The relay under the dash is only to isolate the 12V truck power from the 24V solenoid. In a 12V conversion it isn't needed so you can connect the purple and purple/white wires together to eliminate the relay and a potential point of failure in the system.

Later,
Joe

Why didn't I say that, in post #8! It's exactly what I was trying to say.

 

[math1960]

Thanks, I'll check all this when I have time this weekend. All I did was what was in the instructions. I used the 24volt starter and had it rebuilt to 12volt. I hope ya'll check this thread Saturday, I will have questions then. Thanks for the help.

Wally

 

[math1960]

Problem fixed! Had the wires hooked up wrong on starter. Runs like a champ now. Thanks for the input. Question, does the wait light stop coming on when the engine is warm? It came on a couple of times when testing engine then nothing?

Thanks, I'll snap some pictures and post later.

 

[rnd-motorsports]

Yes if the engine is warm and glow plugs not needed then the ligth will not come on