Im back----- about 2 months ago had a problem with voltage too high . Did the external VR thing and got everything working . Yesterday in the middle of sanding roads , look down and it's not charging. Get it back to the shop to check out. Check the wiring and everthing looks good. Full field the alt. and no change . Get a rebuilt , put it on , and still no change. Go get another VR and put it on and get some charging , but not great , a little shy of 14v. Today start it up and no charge. Full field the alt. and get 17v, put on another reg. and no charge. Load test the bat seperately and both are ok . Checked the 120a fuse and it's ok. Tack is working. NOW I'm lost----HELP

 

Sounds like some bad wiring , intermitent , short.

 

I assuming your using a multimeter or other instrument to check the voltage and not relying on the OEM gauge? Is the truck having any other problems?

 

Multi M reads 12v at battery . Gauge reads correct when I full field the alt so I think it's good. Everything else seems to be working. Ran it for about 2 hours the other night like that , with everthing on and it never quit.

 

I'm not sure if your just leaving a little off cause its easy , but if the meter does say 12 vs. 12.75 then your voltage is low , it may not seem like much 1/4-3/4 volts but as for starting an eng. especaly diesels that much less and especaly when cold is a lot , thats a fully charged[12.75] battery with the eng. off. Then with the eng. running is that idle or what rpm , to charge you want a steady 1,200-1,300rpm min. for charging voltage verys depending how discharge the batt. is , at high idle and discharged batt. the voltage should be about 15-17.

 

John , My MM has a small scale 0-50v , it's reading 12v+ as far as I can tell, doesn't matter if at idle or 1500RPM. If I full field the alt. I get 17-18v at the battery and the dash guage. Everything points to a bad regulatorbut I have put 2 new one on plus the orginal from 2 months ago, what are the odds. Does anyone know what the ohm readings should be on a good regulator, or another way to check it?
Thanks, Bob

 

Still haven't figured this thing out. We have 8" of snow coming tomorrow and I need the truck ( plow ) so this is what I've done . Hooked up a temporary ground wire with a switch in the cab so I can full field the alternator intermitently to keep the battery's up. If I don't let the voltage get higher than 16-17v can I do this without destroying everthing ? I need you help guys , I'm out on a limb . Thanks Bob

 

Think I've got it finally. Out of desparation went down a got another voltage regulator , double and triple checked the wiring , hooked it up and it seems to be working. I think what happened is the alt took out the first VR , the second one I believe was N/G right from the start , the third one I think I fried crossing the wires , time will tell on this one . Thanks too all for the help

 

John here again , sorry I couldn't stick with it , I have to go to a coffee shop to get on the internet and I don't get there every day , hopefully that is the problum , that can get fustrated when you do everything right and find out those parts made by N.A.F.T.A. - they get our jobs and send back defective stuff.