Thread: Guessing I have a bad alternator, flickering lights

Saw the issue again this morning, only my DMM was dead so I couldn't test it. I wanted switch to AC volts and see if anything shows up. I have a $50 off coupon for Advance Auto, and they have a really good return policy. I think I'll just order and alternator and try it out. I hate to drop $200 on a guess, but the $50 off coupon helps. I looked in the yellow pages and every alternator rebuild shop around is long gone.

Buy Worldwide Alternator - 125 Amps P8293 at Advance Auto Parts

Title says its a 2004. The door sticker says made 09/2003. Right in the odd series II/III crossover time. I'll have to double check, as it doesn't seem visually obvious. I'll walk in to the store with it to compare before I pay.

The timing of it is just bad. It's possible that this issue has existed for a while, but thanks to the time change I am only now *starting* the car in the dark.

I see the difference now, thanks. I'll have to double check when I leave work. I've checked a lot of places and almost all are at $199 and up. I liked autopartwarehouse.com before, but even they were expensive. The Advance coupon gets it down to $150, reman'd, and I don't have to ship a core back anywhere. Plus, I'm just testing this, so if it's not the issue, I'd have to eat a restocking fee at most places. Oh, my local junk yard has nothing, which just kills me because of how popular the 3800 is, and one that is further away doesn't have an inventory of them. They say I'm welcome to look and pull.

I know the rebuild place the use to be here would have done it for less than $100.

So all in all, it's the clutch part that costs so much. What does that even do for an alt? Gain back 1 HP or something?

I was able to take a couple of minutes with the DMM this morning.
Before starting the car I had 12.5 volts at the battery, and 12.45v at the alt and the fuse box.
After starting the car (lights flickering) I had 15.9 volts at the battery, 16v at the alt, and 15.9 at the fuse box.
With the car running, and after the flickering stopped, all voltages had dropped .5v.
My DMM doesn't read fast enough to show me if the DC voltage was jittery. I'd like to read it on a scope to see if it's still square, but I don't have anything to do that with.

I don't know about this car specifically, but without mods I should be putting out about 14.5 volts from the alt right? I was also able to measure around .2 volts AC on the alt. After the flickering stopped, that was around .1v.

I did verify that I have a clutch alt as it has that plastic cap on the pulley.

Something else I noticed is that the alt does not connect directly to the battery of the fuse box. My first thought was "how stupid to route the power trough other points before the battery and the fuse box". But then I wondered if that wouldn't actually buffer the system from erratic alt voltage.

I did look for a voltage booster. I saw it somewhere in this forum before, but it's just a stock connector.

I think I will run some new cable. I'll just but a roll of 4 gauge and start rewiring the main connections. I'd like to convert to side post anyways, so it's a good time to do it. I noticed the grounds were tiny too, so probably upgrade all that too.

Thanks for the info. I ordered a new alt for pickup and we'll see if it changes anything.

I picked up a new remaned alt yesterday and dropped it in today. Started the car up without any flickering of the lights. I checked the voltage output on the alt and it was a tad high at 14.7v. After about a minute, the reading was down to 14.4v, and with some extra load on the system, it dropped to a low of 14.2v. All-in-all I'm happy. The old rule of thumb was 13.5v-14.5v, so I'll run with this. I also picked up and installed a pre-made 30 inch cable from the alt to the fuse box. No obvious gain from it, but the voltage reading was identical to the alt output instead of the previous .5v drop. I think as a winter project I'll build a new harness out of 4 or 2 gauge, and make a bunch of new grounds.

Thanks for the help all.