Is there any way to self check the condition of the ecu (elec cont unit) on my vehicle?

Question

My alternator is not charing my battery (i think it may be because the ecu is not telling it to) and the battery gauge needle fluctuates and shakes frequently. The alternator is brand new. I had the battery checked and it is still 80% healthy. The same thing happened a couple of years ago and it was the Computer enginge. Is there any way to self check this?

Answer 1

The electrical system is fairly basic and has little to no outside interferences like from the "Computer" that manages the engine timing and other functions.

A charging systems diagnostic would be your first diagnostic test and these are cheap or free depending on the shop that does it. This checks your battery and alternator and starter.

The other thing that could be wrong is the "new" alternator wasn't installed properly (loose wire) or is defective.

If all of these pass the test, I'd take it to a shop that handles only electrical repairs and have them look for a parasitic draw which could be a short somewhere while the car is running or off. It could be as simple as a loose wire or a wire that has rubbed through the insulation and is touching something it shouldn't intercepting the alternator or battery charge.

Good Luck!

Answer 2

Well you could go to Advanced auto parts and have them hook up a scanner to it. If it has a bunch of wacky readings and codes or no codes it could be the ECU. Or you can go to a junk yard and get one fairly cheap. Then just plug it into your car. If it works that's the problem. If it doesn't then that's not the problem.
And while you're there get them to do a battery charging system check to the car. Your voltage regulator "if it's not internal in your alternator" may be bad.
You could also have a bad battery connection. A loose wire to ground, or to the starter from your battery could cause that too.