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- May 20, 2020
- Reaction score
- Cumberland, MD.
Thanks. Can you be a bit more specific for me? I'll be back at the car tomorrow morning.
This tests the actual alternator, right? I put one lead of my meter on the alternator terminal with the bolt/nut (e.g. the "top" connection to the alternator), and the other lead to the engine block (or even the negative terminal of the battery?), and I should be able to get a reading 13+V read from the alternator, right? If I don't, is that certainly a bad alternator, or could it still be a ECM/computer issue?
-- correct! If the pcm is happy, you should show a charge condition here.
Here's what I have tested:
1. With the car off, battery measured 11.5V (it was drained). With the car started, the voltage did not change, and continually dropped until the battery died. This tells me the alternator is not charging the battery.
2. I disconnected the battery. I touched meter leads to the top bolt/cable of the alternator, and the other end of my lead to the positive terminal of the battery. I'm not sure what what I was measuring, but I was able to get a resistance reading. It was kind of all over the place, but touching them did change my meter reading - but sometimes the resistence reading read 0. If there's a specific way to test, please let me know. I can do it tomorrow.
-- doing this - you are measuring voltage drop between the battery and the alternator. Should be a steady reading - not jumping around. If zero, the fusible linkis shot, as there is no way for the alternator to get charge to the battery. Visualize if you will, a long garden hose with a splice in the middle. If the splice is open, no water for you!
I glanced at the fuse box, and all the fuses "visually" looked okay.
-- no worries! You are willing to listen and learn!
Looked does not equal ok. Must measure electrically.
Apologies for not knowing the right terms/methods here. I really appreciate all of your help.
See the link below for ScannerDanner's methodology. He walks thru much more clearly that i have a hope of.
The 'old school' method, was to ground or power the field / exciter wire and see if you get a charge.
Nowadays, they pop the alternator off and get it bench tested at the local auto parts store. Beware - all store staff are NOT ADEPT at checking the alternator's performance.
Let's fix this thing!Again, if anyone has a shop recommendation near Montclair, NJ, please let me know.