New Alternator and Battery, but battery still dies while running!

[Bxcliff]

Hey guys I'm new to the forums, I have a 2003 GMC Yukon Denali AWD 6.0L that I let sit in the cold for a while here in upstate NY.

I bought a new battery for her but it wasn't keeping it's voltage so I suspected it was the alternator going bad, which was the oem, I've never replaced it before.

With those new parts in, my truck still runs off the power from the battery and the alternator isn't charging.

Before I go more into this investigation, I just want to hear other people's opinions and ideas on this situation. Any help would be much appreciated.

Also if it helps or has to do with anything, my instrument cluster has been acting up before winter and now it doesn't work at all.

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[Scottydoggs]

it starts and stalls out fast after it starts or down the road? id start with fuel pressure test.

mice like to make a home in air filter boxes too, worth popping it open to see if anyone's home. the nest they build can block your engines air intake.

the cluster can be removed and it still runs and drives. so that likely needs to be sent out for rebuilding.

 

[Bxcliff]

it starts and stalls out fast after it starts or down the road? id start with fuel pressure test.

mice like to make a home in air filter boxes too, worth popping it open to see if anyone's home. the nest they build can block your engines air intake.

the cluster can be removed and it still runs and drives. so that likely needs to be sent out for rebuilding.

The truck runs perfectly fine mechanically, fuel lines and tank does not have frozen water vapor. It's just when I drive all my lights get super dim and when I shut it off it won't start again because the battery died

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[RED TAHOE LS]

Clifford..........to the forum from Georgia Dawg country. If the electrical system is running below 9-10 volts, it will cause instruments to be erratic, even the tachometer. With everything else being ok when running, my gut tells me you got a bad Alternator, it happens. I f you can see the back of the Alternator in the center, there's a bearing right in the middle. With the engine running, take a knife blade that will reach that bearing area and see if it STICKS while running, if NOT, the Alternator is NOT any good. Always double check your connections and make sure they are ok. IMO, use only AC Delco parts including the battery. Good luck.
David g...........

 

[Scottydoggs]

how old are the battery cables? from 03 still if im guess right? if you see any bare wire at the ends of the cables good chance they are shot. they get dry wire and currant cant pass through.

have you tested the voltage at the battery engine running yet? most parts stores can do this for you for free. if its less then 12, should be 13+ running, the new alt is also bad most likely. ive had 2 bad rebuilt alts in a row just a few months back. it happens. parts store should also be able to test the alt on a bench to make sure its the alt. and lets face it, a alt swap in a parking lot's not a big deal on these trucks. even if its just to be tested.


or you've got a huge power draw somewhere and you need to start probing every fuse to see what one is drawing all that power.

might have some thing to do with the harness of wires where the cluster plug comes from, hard to say really.

 

[Bxcliff]

Clifford..........to the forum from Georgia Dawg country. If the electrical system is running below 9-10 volts, it will cause instruments to be erratic, even the tachometer. With everything else being ok when running, my gut tells me you got a bad Alternator, it happens. I f you can see the back of the Alternator in the center, there's a bearing right in the middle. With the engine running, take a knife blade that will reach that bearing area and see if it STICKS while running, if NOT, the Alternator is NOT any good. Always double check your connections and make sure they are ok. IMO, use only AC Delco parts including the battery. Good luck.
David g...........

That's why I suspected the alternator I had was no good. I replaced the bad alternator which failed 3 times when I went to an auto zone to test it with a new alternator which ran the same amperage as the old one

Should I still do what you recommended with the new alternator?

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[Bxcliff]

how old are the battery cables? from 03 still if im guess right? if you see any bare wire at the ends of the cables good chance they are shot. they get dry wire and currant cant pass through.

have you tested the voltage at the battery engine running yet? most parts stores can do this for you for free. if its less then 12, should be 13+ running, the new alt is also bad most likely. ive had 2 bad rebuilt alts in a row just a few months back. it happens. parts store should also be able to test the alt on a bench to make sure its the alt. and lets face it, a alt swap in a parking lot's not a big deal on these trucks. even if its just to be tested.


or you've got a huge power draw somewhere and you need to start probing every fuse to see what one is drawing all that power.

might have some thing to do with the harness of wires where the cluster plug comes from, hard to say really.

Never touched or replaced anything electrical related under the hood besides a few batteries being swapped over the years since I've owned the truck in 2005. I will definitely try to test the voltage of the battery with my multimeter and then see if I have something draining the battery.

Does the alternator on my truck have a fuse? If it does that could be blown possibly

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[swathdiver]

Boy, the only cars I owned at 5 years old were Hot Wheels and Matchbox!

 

[Bxcliff]

So I figured it out based on what you guys have been telling me, I tested all the wires connected to the battery and the alternator and also checked if anything was draining the battery. The alternator wire to the battery wasn't good so I replaced it and it hasn't died since

Thanks for your help guys I appreciate it [emoji106]

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[PG01]

So I figured it out based on what you guys have been telling me, I tested all the wires connected to the battery and the alternator and also checked if anything was draining the battery. The alternator wire to the battery wasn't good so I replaced it and it hasn't died since

Thanks for your help guys I appreciate it [emoji106]

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Was just going to tell to remove/replace your battery cables... glad you got it sorted