Alternator Replacement Info
 

My alternator may have died on my Uplander LS 3.5. Checking around, no one in town stocks the 105amp unit, only the 125amp. My OE is 105amp, but the dealer tells me that their system is changing everything up to the 125amp with a new regulator included. The dealer would have to order it in overnight.

Question I have is am I safe buying a 125amp unit from a Jobber in town today, with the possibility that the regulator is incorrect, or should I just spend the extra to get the GM OE one with the new regulator overnight? Keep in mind that I do not have time to make one choice, find out it's wrong, and then have to take another day to order and install another unit.

Thanks.

I think in your last statement you answered your own question... go with the OEM and all should be good...:cool:

Agreed - stick with the dealer part. Sometimes you're just better off.

FWIW - With our Venture we always had flickering lights from day 1 and once the original alternator failed and I replaced it with the updated one all the flickering was gone.

hope you tested it properly as these are expensive ecm controlled alternators.

Make sure you check the output at the alternator. Loose connections at the starter solenoid are common. This can cause an alternator light to come on as the alternator output cable runs to the starter solenoid and then to the battery.

Turns out it was just corrosion build up on the posts and terminals. Cleaned it up, charged the battery, and all seems good.

442Dude: I've had the same "dimming/flickering" problem from day one as well. They always said this was "normal". The voltage drop when you hit the brake sometimes is enough to interrupt power to any 12V devices you have plugged into any outlets.

PG2676, thank you for posting your outcome. It will likely save a lot of us some grief down the line.

Bob R

Yeah - we bought ours used and everything I found out told us it was normal for the Venture too. I would notice that the headlights would lightly flicker while it was idling in the driveway. I even found some TSBs about it where they talked about shielding wires and such, never bothered to take it to that level as we only really noticed it at idle and never had an issue where the battery wasn't charging. Once I put in the new alternator with the new higher amperage the problem went away forever. The thing had power everything so the alternator was likely undersized from day 1.

Glad to hear that you didn't have to replace the alternator after all. I did the Venture one in my driveway. Took about 6 hours by the time I took all of the stuff of that had to get out of the way and then rotated the engine so I could actually get the old one out and finally put everything back together. It was a job to be proud of for a backyard wrench turner but not something you'd want to do on a regular basis!

pretty sure there is a tsb about replacing the voltage regulator to cure the flickering light issue.

Was that the 3.4L where the alternator was located on the bottom somewhere behind the passenger front wheel? If it was, I don't envy you. I remember having to replace the same one on a 3.8L Grand Prix. Two mechanics and about 6.5 hours. What a pain in the ass!

Oh yeah it was! - the alternator was passenger side up against the middle of the firewall under the wiper mechanism and covers. No way to get to it other than to spin the motor. Feeling pretty good that it was only me and 6 hours vs 2 mechanics and 6.5 on the Grand Prix! Pain? Absolutely!!!!! LOL