Electrical bugs

[TX LTZHoe 07]

I have had a few bugs in this tahoe since I bought it last semptember, but most of them were fixed fairly easily, while under warranty. Now that my warranty is gone, there are some new issues that are starting to scare me.

The dealership replaced the alternator some time ago whenever it was determined to be causing a "whine" through the stereo. However, the alternator gauge still acts strangely IMO. Under normal running and little electrical load (rear A/C off, lights off, etc), the gauge shows to the left of the middle mark, less than 14 volts. Whenever one or all of those things comes on, which I would consider a substantial load on the system, the voltage jumps up to over 14 volts, to the right side of the middle mark. This seems counterintuitive.

Secondly, I replaced my battery 2 weeks ago. The AC Delco wouldnt hardly hold a charge anymore, and I replaced it without taking it back to the dealership. Now the "whine" through the stereo is back, but not as bad as before.

And then recently, with the HVAC in "Auto", the fan is acting weird. It has been in the 90's lately and when you first get in the car, the fans obviously go to high speed so that it can cool the car down. However, the fan speeds seem to surge now - to a speed higher than they have ever been, and then it drops back down to normal high speed, and then back up, cycling back and forth. I have not tested it, but I dont think it does in whenever it's not in Auto. I am driving it today to get a better diagnoses...the wife drives it majority of the time.

Anybody have any ideas as to what could be causing all of these problems? I dont have a warranty, and I dont want to spend thousands for the dealership to diagnose these problems.

 

[Modded]

I have not seemed to have any of those problems, excluding them first one.
I have the exact same issue with my alternator whining and voltage meter acting weird, I am thinking about making them warranty it soon.

 

[steven johnson]

alternator goes's to stand-by mode when its not needed. that's why your voltage meter drops. Its normal Per. GM service center

 

[TX LTZHoe 07]

alternator goes's to stand-by mode when its not needed. that's why your voltage meter drops. Its normal Per. GM service center

Thats kinda what I was thinking it seemed like it was doing, but I dont quite understand how it does it. Is it not charging all the time?

 

[91RS]

The ECM can control how much charge the alternator puts out and when. Like during WOT the ECM will turn off the alternator charging. I would says your's is operating normally.

I would recommend not using the Auto HVAC. It keeps moving actuators around to get the temperature you want and just wears things out faster. I always recommend only using it in "manual" mode. The fan surging is probably something to do with how the auto system is working.

 

[rogersinsel]

I have had a few bugs in this tahoe since I bought it last semptember, but most of them were fixed fairly easily, while under warranty. Now that my warranty is gone, there are some new issues that are starting to scare me.

The dealership replaced the alternator some time ago whenever it was determined to be causing a "whine" through the stereo. However, the alternator gauge still acts strangely IMO. Under normal running and little electrical load (rear A/C off, lights off, etc), the gauge shows to the left of the middle mark, less than 14 volts. Whenever one or all of those things comes on, which I would consider a substantial load on the system, the voltage jumps up to over 14 volts, to the right side of the middle mark. This seems counterintuitive.

Secondly, I replaced my battery 2 weeks ago. The AC Delco wouldnt hardly hold a charge anymore, and I replaced it without taking it back to the dealership. Now the "whine" through the stereo is back, but not as bad as before.

And then recently, with the HVAC in "Auto", the fan is acting weird. It has been in the 90's lately and when you first get in the car, the fans obviously go to high speed so that it can cool the car down. However, the fan speeds seem to surge now - to a speed higher than they have ever been, and then it drops back down to normal high speed, and then back up, cycling back and forth. I have not tested it, but I dont think it does in whenever it's not in Auto. I am driving it today to get a better diagnoses...the wife drives it majority of the time.

Anybody have any ideas as to what could be causing all of these problems? I dont have a warranty, and I dont want to spend thousands for the dealership to diagnose these problems.

WHat you are describing for your alt. gauge is normal.

 

[Zed 71]

Alternator gauge flux is normal per GM. It is an on demand type operation.

 

[Maccam26]

The ECM can control how much charge the alternator puts out and when. Like during WOT the ECM will turn off the alternator charging. I would says your's is operating normally.

I would recommend not using the Auto HVAC. It keeps moving actuators around to get the temperature you want and just wears things out faster. I always recommend only using it in "manual" mode. The fan surging is probably something to do with how the auto system is working.

Auto HVAC has been around for many years, is your recommendation based on substantial evidence that components would wear out faster by using the system? What parts do you believe this would impact? Just trying to see if I can stomach repair costs if facts support this claim. Thanks.

 

[Northern Ont]

Thanks for the info about the Voltmeter and Alternator. I was going to ask the same question, mine does the same thing. Nice to know that it is normal.

As far as a noise in the stereo, if you moved any main power wires when you changed the battery, that is probably what is causing the noise. If the main power wire for the stereo is too close to another power wire (or the main battery + or -), it can sometimes cause RF interference. Just check by moving the main power cable over an inch or two one way or another, sometimes it doesn't take very much to clear up RF noise.

I don't have any ideas for your HVAC. We only use AC up here for about a month a year, although I prefer the sunroof and the wind in my hair. Damn Canadians!

Later,
Rob

 

[OklabyGodhoma]

Your variable fan speed may well be due to your controller "breaking down". Fan circuits are actually done with a resistor bank causing a controlled voltage drop to the motor when you change speeds. If you have the fan set on one speed and the fan speed keeps changing on you I would look into this. An easy way to diagnose this is to set the fan at different speeds....if it only goes "variable" in one setting and not in others then that is the circuit that has the bad resistor. It is usually a bank "assembly" that has to be replaced....the good news....not that expensive.