changed bad alternator and still wont keep charge
Asked by PittbullGirl Mar 10, 2022 at 03:21 PM about the 1998 Ford Expedition 4 Dr Eddie Bauer 4WD SUV
Question type: Maintenance & Repair
changed out a bad alternator and had new one tested before i put it on , started
truck with cables and when i disconnected the cables it died. is there a voltage
regulator on this model and what does it look like?
3 Answers
It's part of the ECM, Check for any blown fuses in both boxes, does the battery light turn on when you turn on the key? That light is part of the exciter circuit for the alternator, so if it doesn't work the alternator won't either. Hopefully it is not the ECM as you may have trouble finding parts. I have been waiting for 8 weeks now for a BCM.
beatupchevy answered 2 years ago
If your new alt had to charge a dead/low battery that may have killed it .
You should never EVER disconnect the battery cable with the engine running! It will create a power surge that will blow fuses and fry electronics in a matter of seconds, literally!! This is a very old fashioned way to check an alternator/generator that should never be used today! In fact I once did that to a 1970 Pontiac Catalina and I successfully blew out the headlights, taillights, and the fuse for the instrument cluster lights! Luckily for me there were no computers involved!! Jim
