electrical issue

[lolo33]

Hi all,

got a problem with electricity : after changing my battery which was over, I controlled level of charge = more than 18V - i thought it was an issue with regulator ==> so I changed the regulator (LMC part 36-2520), drove my PU and after 3 or 4 runs : battery flat !
So verified level of charge = 12V. decided to change the alternator (LMC part 36-2760-Z external regulator). verified the level of charge = 12V !

what could be the problem with please ?

thanks for your answers

[Ol Blue K20]

get a volt/ohm meter and make sure you're getting power to alt, ohm check voltage reg harness. But my bet is the voltage reg, go to parts store and get one. There is no need to use LMC for these service parts
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[Shyguy]

When the truck is running the voltage should be in the 13.5-14.5 range.

It is real difficult to work on electrical issues without a volt ohm meter.

Like Dale said, the parts you bought at LMC are available at most auto parts stores. I try to buy everything I can locally, easier to return and I get to compare parts.

[lolo33]

Sorry, but from France, LMC parts, Eckler's or Classic industries are my possibilities. No parts in france for C10 :-(

[Ol Blue K20]

Sorry didn't notice that on my little phone screen dang foreign cars with no parts availability! but on a serious note a quick check on the wiring. But since it was overcharging and quit charging when you changed the voltage reg. that's where my vote for the problem is. That voltage reg is not exclusive to the truck so I might check parts stores there just for grins!

[lolo33]

I know that "standard" charge is +/- 14V when engine is running. So THAT'S the problem : with my volt/ohm meter only 12V (check on battery plugs and alternator plugs = same voltage = 12V)
what kind of pb with wiring ?

laurent

[Ol Blue K20]

First and foremost is make sure there is 12v on the back of alt. second you're just checking continuity and making sure you don't have excessive resistence. I'm not sure how to do links on here but do a search there's downloadable service manuals for each year, that will have wiring schematics. They will also be invaluable to you as there will be step by step diagnostic procedure for you.

[lolo33]

thanks for answers, even I don't have a good understanding sometimes;
today bought a new amp/volt meter in order to check better. if I don't find the issue, will go to my specialist...

[Ol Blue K20]

I still think the most likely thing will be voltage reg....

[lolo33]

you're probably right, but it's a new one !

[VetteVet]

Did you make sure the regulator was grounded to the core support? It is mounted on some rubber grommets called wells plugs and a separate wire needs to be run from the regulator body to the core support. I is also supposed to be grounded to the alternator as well, but if the alternator is grounded to the block and the block is grounded to the negative battery cable then it should work just fine.

If you could upgrade to an internal regulated alternator you would be able to get more power and reliability. If you don't get the alternator charging and want to convert then start a thread in the electrical section and we'll show you how easy it is.

[lolo33]

yesterday, I bought a new electronic multimeter... and it works.
voltage at 750rpm = 12,4V
voltage at 1500rpm = +/- 13V and grows up
other change, after engine running, truck start's at first turn key !

Now I can drive my C10

[Ol Blue K20]

Good , glad you figured it out
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[lolo33]

in fact, I'm not sure that my old alternator was over.
The Multi meter I had was an old one, and not sure that indications it gave were right !
So I am going to keep it (alternator) in case...

Thanks for all your help