Need some advice on which direction to go

2014 Tahoe 177k miles. So the last few days, it’s been getting pretty cold and I noticed my truck kinda bogs down like it’s gonna stall for a split second when first starting it and than rpm go back up. I did a battery and alternator test with my OBD reader and it passed on battery but alternator failed both tests. (Took two to make sure) it has me hold the RPM at around 2000 for 20-30 seconds. So OK I’m like all right no big deal. I’ll order an alternator and get it taken care of. But I wanted to be 100% sure so I took it to AutoZone and have them tested with their little thing and I guess they are telling me my starter is failing and that my alternator and battery are fine. So I guess I’m confused because results are contradicting each other.

its ok, the scanner is just a generic thing that was probably right for older vehicles without computer controlled charging.

mikez71 said:

its ok, the scanner is just a generic thing that was probably right for older vehicles without computer controlled charging.

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Thanks for the reply… what’s ok exactly?

And I also had auto zone run some tests. There reader said starter was bad. But then again, everyone tells me not to trust AutoZone or any parts store for that matter.

honestly it's probably voltage drop in wiring and ground more than actually hard parts.

hard to saw without hands on thou. how old is the battery?

if more then say 3 or 4 years, I'd replace it with winter coming and replace the postive and neg battery cables, clean up the ground while replacing

Can you post up video of what is actually happening?

89Suburban said:

Can you post up video of what is actually happening?

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So for the bogging down thing for the split second after starting it, seems to be on the first initial start of the day after leaving the truck sit overnight or when I started after work after letting it sit all day it will do it. I’m gonna try to catch it tomorrow on video for you.


It just seems like when i start it first time in morning it will turn over and crank just fine but AFTER it starts it’s supposed to kinda rev the RPM up and than drop down. Well sometimes it doesn’t do that, it will just bog down like it’s gonna stall out and than will barely catch up and keep the vehicle running and than rpm’s go to normal. And this is all happening within like 3 seconds. Hopefully that sheds more light

j91z28d1 said:

honestly it's probably voltage drop in wiring and ground more than actually hard parts.

hard to saw without hands on thou. how old is the battery?

if more then say 3 or 4 years, I'd replace it with winter coming and replace the postive and neg battery cables, clean up the ground while replacing

Click to expand...

I can’t speak for the wiring system at all or the negative and positive cables for the battery. The battery was in the truck when I got it in March 2023. Acdelco 94r

j91z28d1 said:

honestly it's probably voltage drop in wiring and ground more than actually hard parts.

hard to saw without hands on thou. how old is the battery?

if more then say 3 or 4 years, I'd replace it with winter coming and replace the postive and neg battery cables, clean up the ground while replacing

Click to expand...

I will say I left the sun roof open when i first got it. Rookie mistake it was my first ride with a sunroof. Learned the hard way. I did have some strange electrical glitches and weird warning messages for a couple days after that, but I let it dry out in all of the issues went away, and the vehicle returned to normal. I don’t think that has anything to do with this, but I figured I would just mention it.

mikez71 said:

its ok, the scanner is just a generic thing that was probably right for older vehicles without computer controlled charging.

Click to expand...

I heard these scanners can mimic just enough voltage to get a good reading

Sitting perfectly at idle… would that mean I can rule out the alternator? Sometimes the headlight dim when I first take off as well.

Taking it to my local
Shop tmrw to hopefully get some more answers.