05 gmc charging issues

[gibsons]

Need a little help here. My boys 05 gmc 1500 5.3L vortec died on him and the charging system he said was dropping, so right away I'm thinking the alt. is going in it. next day I went to give him a hand boosting it and do a test to see if it's charging, but it ended up starting fine for him. While I was gone earlier this week it ended up stranding him in a parking lot, anyways I picked up an alternator for him and putting it in but when he came by the house he said it started doing the same thing, charging system is dropping and also his dash lit up saying charging system failure,(it also said this earlier when he originally started having the problem.)
Any one have any ideas? It has a pretty new battery in it as well.

 

[butters]

Dirty or loose connections on the starter.

 

[ippielb]

Check the ground too. Depending on what your kid does if he went off roading the battery ground cable could be damaged.

 

[ABMax24]

As said above check all connections, start at the battery and work out from there

 

[gibsons]

Thanks fellas, I'll check it out today and let you know what I find.

 

[medler]

I would check the connection right at the alternator. I know if you unplug that it will say " charging system failure on the dash. Gotta be a bad wire there somewhere

 

[gibsons]

Thanks Mike, I'll check that out as well.

 

[X-Treme]

I would check the connection right at the alternator. I know if you unplug that it will say " charging system failure on the dash. Gotta be a bad wire there somewhere

^^^^ this. Particularly the connector with the small wire(s) going to it. If you can get the truck to act up, and THEN wiggle that connector to see if it changes anything, there's your easiest test. I wouldn't worry too much about the connections at the starter. Highly unlikely that you'd see what you're seeing. Alternator, grounds and battery first. In that order.

 

[gibsons]

Hmm, cleaned up the battery even though it looked fine, the ground seems to be ignorant to get to so I will have to get it over to my brothers tomorrow to put it on the hoist. Had it running and the volts dropped eventually then the light and charging system indicator came on. Tried playing with the plug and wires on the alt. for a bit and there was no change. Like I said, when I get to my brothers tomorrow I guess I'll work on the ground and check out the starter. This is frustrating!!!

 

[X-Treme]

It's possible you got a faulty alternator too. Sure wouldn't be the first time I've seen that happen.

 

[doorfx]

X2 put a meter on it and see what you have for voltage. It can save a lot of time troubleshooting

 

[nwoprormk]

X2 put a meter on it and see what you have for voltage. It can save a lot of time troubleshooting

Battery could be shorting inside......but intermittently due to thermal expansion. Seen that before. Put a diff battery in to check

 

[gibsons]

turns out the new alt. was crap!! good to go now, thanks for your help fellas.

 

[growly]

out of curiosity......what brand of Alt.?

 

[gibsons]

I don't recall. I want to say Wilson for some reason.

out of curiosity......what brand of Alt.?

 

[Nipper]

On small plug on back of alternator, ( I believe there are 2 wires in plug ) one of the wires goes to the dash light and the other supplies power to turn on the alternator. With the key on you should have around 5 volts on one of the wires. Some will have 12volts. If voltage is there when you are experiencing the charging problem, most likely a alternator issue. Make sure the proper belt is on the vehicle and the tensioner is working properly as it will not turn the alternator fast enough if the tension is slack.; Hope this helps

 

[X-Treme]

On small plug on back of alternator, ( I believe there are 2 wires in plug ) one of the wires goes to the dash light and the other supplies power to turn on the alternator. With the key on you should have around 5 volts on one of the wires. Some will have 12volts. If voltage is there when you are experiencing the charging problem, most likely a alternator issue. Make sure the proper belt is on the vehicle and the tensioner is working properly as it will not turn the alternator fast enough if the tension is slack.; Hope this helps

He already found the problem. Faulty replacement alternator.