Alternator not charging

It sounds like the fusible link has blown

https://www.2carpros.com/articles/how-to-check-a-car-alternator

there is a fusible link. Check out the diagrams (Below). Let us know what happens and please upload pictures or videos of the problem.

Hello,

This sounds like the alternator is not working here are two guides to help you test and change the alternator out.

https://www.2carpros.com/articles/how-to-check-a-car-alternator

and

https://www.2carpros.com/articles/how-to-replace-an-alternator

Here is the alternator on Amazon for $116.00 AC Delco

https://www.amazon.com/gp/product/B007QBR5TA/ref=as_li_qf_asin_il_tl?ie=UTF8&tag=2carprcom-20&creative=9325&linkCode=as2&creativeASIN=B007QBR5TA&linkId=02ce236df38f8f1d189aefbb46980824

Please let us know what you find.

Hi kemperdog. Welcome to the forum. There is some good news in my reply. There is no way to sugar-coat the bad news though. It is a well-known fact that GM went from the second best charging system in the world to the worst pile ever produced beginning with the 1987 model year. It is common to go through four to six generators, (aka alternator, but that term is copyrighted by Chrysler), in the life of the vehicle. They are extremely difficult to disassemble and just as difficult to identify the defective components so most people just replace the entire unit which includes the voltage regulator.

The good news is if this is the first time you have had charging system trouble in 172,000 miles, you are doing way better than average. The second bit of good news is more and more mechanics are learning that to prevent repeat failures, the battery, which might work just fine in any other car or truck, must be replaced at the same time. Since your battery was just replaced, you will likely not have a problem with your new generator.

Due to the design of this generator, they develop a lot of voltage spikes. Special "zener" diodes help to dampen most of those spikes, the ones that get through can wreak havoc on the many computers on the truck. Sensor voltages vary by a few hundredths of a volt. Voltage spikes affect sensor readings and will make the computers respond to the wrong things and do weird things. GM generators are a known cause of engine performance problems even when they are still keeping the battery fully charged.

As the battery ages, its "internal resistance" goes up which lessens its ability to absorb and dampen voltage spikes. That is why replacing the battery when the generator is replaced will make the generator last longer.

There are tests you can do on the charging system, but you already noticed the voltage reading is low intermittently. Everything is self-contained in the generator. The only other thing that can cause it to stop charging is a break in the small red or brown wire that plugs into the side of it, but that is also the wire that turns on the warning light. Since the light is working, that wire must be okay too.

Here are the wiring diagrams and a guide to help you test the wiring

https://www.2carpros.com/articles/how-to-check-wiring

caradiodoc

Did you test the fusible link between the starter and alternator? Is the alt receiving power?

Let me know what you find. I bet that is the problem. Also, make sure to check if the alt is getting power.

Check all the connections for the alt.

The idle has to re learn after battery replacement

Roy

Should have the charging system checked ASAP

Hi there,

have the battery load tested, this will prove the viability of the battery, check alternator charge rate, will need to be over 13.5 V min check battery terminals are clean and tight and chassis earth is ok. Do you run an Amp? Is it powered up with key off? If so this will drain battery.

Mark (mhpautos)

Could be the computer controlled of the alternator field generation circuit-have it checked

Even thought the alt is new, has it been checked. If it has and it is good, I believe there is a fuseable link between the alt and the engine that may be your problem.

Joe