generator, regulator

buzzk · Post by **buzzk** » Sat Jun 21, 2014 5:05 pm

Over the years you learn how to check voltage on 24 volt systems One way Iv'e learned is to disconnect the negative battery cable next to the rad to check if the system is putting out , if it doesn't cut off its putting out or check the voltage with a meter. Mine is not putting out the correct voltage The question I have is will a M151 regulator work on a M38 same w/ the generator and how does one check each one Sunday I'll take to regulator off and put on a M151 and see if it puts out the correct voltage The jeep is alive and driving around the neighborhood Buzzz

Post by **wesk** » Sat Jun 21, 2014 5:50 pm

In some systems breaking the battery circuit can often times damage sensitive electrical equipment. I would suggest a $30 digital voltmeter be added to your toolbox. Then you can check your systems operating voltage 10 times faster then taking the battery ground cable off with no risk to the equipment.

With M series vehicles try to ID electrical components by part numbers and ratings not vehicle models. There are at least 4 combinations of gen/alt/regulator used on the M38 and M38A1 that are also used on many other M series trucks including the M151. For example, don't try to use the regulator off a 60 amp system on a M151 on the 25 amp system on your M38. Or don't try using the regulator off the 100 amp M38A1 system on a 60 amp or 25 amp M151 system.

Open your parts manual and write down the model numbers of the applicable regulators for your jeep. Compare your numbers to the numbers on your jeep's regulator. There should be at least one match. Now before you borrow one from another M series truck read the model number on the regulator. There are four regulator model numbers that can be used on a 25 amp / 24V M38 or M38A1 system. Two auto-lite/prestolite, one Delco Remy and one Transistorized regulator made by three or four different manufacturers.

The expensive way to troubleshoot electrical systems is to use the plug and play system. In this system you either get extremely lucky and what you plug in works or you get extremely unlucky and you see smoke.

buzzk · Post by **buzzk** » Sat Jun 21, 2014 5:54 pm

I have a meter its only putting out 12.2 volts no matter how I connect it I'l check the numbers to see if they match buzz

Post by **wesk** » Sat Jun 21, 2014 6:49 pm

You check system voltage from the cable on the battery that attaches to the starter switch and ground. If you use the other battery plus cable you will read only have the system voltage.

buzzk · Post by **buzzk** » Sun Jun 22, 2014 8:33 am

Yes checked the # 2 battery buzz

buzzk · Post by **buzzk** » Sun Jun 22, 2014 12:38 pm

O K The regulator I have is for a 24 volt system , neg ground The serial # are close 25 amp they both match as far as the specs buzz

Post by **wesk** » Sun Jun 22, 2014 1:33 pm

what are the part numbers for the two regulators? Close only counts in horse shoes and hand grenades!

buzzk · Post by **buzzk** » Sun Jun 22, 2014 2:19 pm

To late,It's already on the jeep Putting out 24.50 volts Buzz

Post by **wesk** » Sun Jun 22, 2014 5:01 pm

Too early to brag. They should be putting out 28 volts!

buzzk · Post by **buzzk** » Sun Jun 22, 2014 8:32 pm

yep I know I'll recheck tomorrow I have one more regulator in my stash thx Buzz