The other day, I take the truck for a drive. After getting home and turning it off, I go to turn it back on a couple minutes later, and it won't turn over, like the battery is dead. I check the battery and it's quite low, so I charge it up, start the truck up. I check the voltage with my multimeter at the battery, and it's 11v with the truck running and all components on. I get the same reading at the alternator. I assumed the alt was bad. I put this alt on a few months ago. It's a Duralast reman from Autozone.

I take the alt in and they exchange it for free. Their alternator tester wasn't working, so I don't know if it's bad for sure. I install the new alt, start the truck up, exact same reading, 11v at the battery and the alternator.

What else could it be? Voltage regulator? This truck has the external voltage regulator which I did not replace a few months ago with the new alt.

 

Well, I think you answered your own question, replace the voltage regulator.

I also believe there is a way you can test the ALT output on the truck.

You could ask google "How to test..."

Also you could take your ALT to another store that test's them for free.

There also experts on here that can link you to the test or tell you how to.

Have you scrolled down this page to the "related topics "

 

A full field test on the ALT bypasses the regulator and should put out as much volts as it can and why you don't do a full field for a long time.

Did you check the plug connection at the regulator?
Is it grounded good to the inner fender?
Can also run a wire from the body of the ALT to regulator to see if that could be a issue. Jumper cable would work for testing.
Dave ----

 

The EVTM is here:

https://www.garysgaragemahal.com/cha...ution-gas.html

That's for 1985, but I believe your 1984 should be very similar.

Do you have an ammeter or idiot light? The wiring is different, so make sure you use the correct diagram. Normally the EVTM includes some good troubleshooting info, but in this case it just sends you to the service manual. I can check mine tonight if you don't an answer before then.

As Dave has suggested, make sure the regulator frame is well grounded. Don't rely on the inner fender where it attaches. I STRONGLY suggest adding a ground wire (10 ga?) between the alternator case and the regulator base, and from there to the battery (-) terminal. IIRC, a bad ground for the regulator typically causes overcharging, so this likely isn't your fault, but I'd add the ground wire anyway.

While you're at it, CHARGE THAT POOR BATTERY!!! Even after you get the charging system back up to snuff, don't rely on it to fully replenish the battery. You also want to have a fully charged battery before you begin any electrical troubleshooting, so please don't skip this important step. A partially discharged battery can skew your test results and cause you to condemn some perfectly good parts. I do not care to discuss how I know this...

I forget all the details of how to test the regulator. It's pretty simple to do. Until we can get you the details, you may want to just gamble $10 and try a new voltage regulator. Your call. Normally I don't suggest loading the parts catapult (Pull!) but you've got a good chance of having a bad regulator.

 

Thanks, I'll read through this.

I'll take a look at the regulator grounding tonight, but I'll probably just replace it either way.