My 2008 Chevy uplander I change alternator and the battery excellent but the alternator fail to charge

SOURCE: new battery and alternator. Battery still won't hold charge

Check all your fuses if you had a system failure it could have blown a fuse. I am not sure on your vehicle where the fuse is in the car or under the hood it could also have a relay. You can check your alternator by checking the voltage at the back of the alternator where the big wire bolts on. You should have 14+ volts at the alternator.

SOURCE: 2003 Chevy Suburban, Alternator failed,

I would look for a short in the output wiring at the alternator. My nephew had an intermittent charging problem and I took the car to an autoparts store and had them check the alternator output. Most parts stores will do the check for free. Anyway, while it was hooked up and the output was being checked, I fiddled with some of the wires at the alternator to see if it had any effect. It did. I noticed that as I moved the wires around, the output changed. I was able to isolate the problem to a wire that ran inside the plug. I resoldered the wire and that fixed the problem. I'm not saying that your problem is the same, but I would definitely look at a wiring short somewhere. I sympathize, since there is nothing more aggravating than finding the source of some electrical issues. Anyway, I hope this helped and that you find a resolution to your problem. Best wishes.

SOURCE: 1986 chevy c-20 diesel, dual batteries - erratic charging

What place verified the alternator for you?
If its a place like Autozone,all they can do is a normal running check of it,They cannot put a load on it to see how much it can put out.It really sounds like the voltage regulator is not changing,maybe one of the diodes are bad in the alternator.

SOURCE: Have 44k on a 2008 chevy uplander. Front left

I have a 2008 as well.. with 39K and the front right needed replaced.
it was covered under the 100K warranty

Donald DCruz

• 17130 Answers
• Posted on Nov 22, 2011

SOURCE: Diagram of a 2008 Chevy Uplander Van 3.9 L engine.

First of all you need to confirm the case of the alternator before it is replaced and I hope that the output voltage from the alternator was checked. However if voltage is present the fault can be with the rectifier/regulator.
Now the alternator is clamped on to the enigne side with the pulley threading in line with the main belt.
You need to have box spanners to remove the side clamps holding the alternator so as to loosen the unit . While refitting the tension of the belt is most important as you need help to keep it tight while the bolts are fastened .
If a new alternator is not purchased then it will be best to have it done at the dealership as the cost of part will include the replacement.So check for estimate before you remove the unit.