Hello, thank you for reading and helping. I purchased a 2004 Cadillac Seville (northstar V8) from a college student because he didnt want to pay the shop to have it fixed. He was driving on the highway and lost voltage and was towed to the nearest mechanic shop. The shop diagnosed the problem as battery and alternator needing replaced, so I jumped on it for a good price.
I bought a new battery for it and it started right up in the parking lot, but I didnt trust it to drive home so I had it towed. I then replaced the alternator. I started it daily for two weeks after this, running it for 20 minutes at a time with zero issues. Once registered, I drove it 50 miles without any issues. The 100 mile trip was the issue, as the car started losing voltage quickly from 14.7 to 13, 12, 11, down all the way to about 8 when we barely made it home. I let it sit overnight, the next day it started up fine, had 13 volts, ran fine for about 45 minutes (parked) then started to lose voltage. I haven't started it since, it's been a week of sitting. Now the battery is completely drained.
The previous owner had a subwoofer stereo system in it, which he removed before selling the car. Just the sub and amp in the trunk were removed. The battery I purchased was specific for this Cadillac from autozone. the alternator was remanufactured from autozone, the $180 one air cooled. I have cleaned up the main ground wires to the frame by the alternator, and near the battery to frame under the rear seat. All fuses are good (except for the blower motor fuse I replaced) . Side note is the car ran fan up until I replaced the blower motor fuse. Perhaps there's a draw in that?
I had autozone test the car when it was losing voltage about 10 volts was showing and they determined the alternator wasnt charging. Even being "new" and a new battery. I'm just wondering what is preventing this from charging? I'm taking off the alternator/battery today to return to autozone for bench testing and will inspect more wires. Any thoughts?
It's very common for rebuilt alternators to be defective out of the box. You're on the right track getting it tested so let us know how that goes. Another possibility is that on many cars the voltage regulator is actually in the ECU rather than built into the alternator as in the past. If your Caddy is set up that way even a good alternator won't charge if that part of the ECU or the wiring to it is bad.
Thanks for your reply. I've heard that about the alternator as well. I chose this one versus the $400 one, but perhaps a better/new one would work better?
I know a guy that can flash/program me a ecu based on my vin #, that was going to be my next step after all this. Any thoughts on that? Ebay has used pcm/ecu for $25 but I imagine they need programmed correct? He said he could have thr part and program it for $100, which seems very reasonable, just unsure if that will fix the problem. Thanks for your reply!
I'd see how that rebuilt alternator tests out so you can get an idea of what's going on. I have not worked on one of those cars though so can't really advise on whether a used ECU would need to be programmed to your VIN, or even whether the ECU controls the alternator output. (Maybe Scotty or someone else who has worked on one can chime in.)
Hello again, both the new battery and remanufactured alternator tested bad at the store. The battery had 13 volts but only 66 CCA. I got both replaced but am leery to install them (again) just for both of them to be drained again. What could be causing this? This didnt seem to happen until I ficed the blower motor fuse, which was blown. Perhaps a draw there?
Unfortunately it is all too common for new parts to be bad, particularly remanufactured parts. Did you have the replacements tested so you have some idea if they're good before installation?