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2006 chevy trailblazer_ls_ext
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Discussion Starter · #1 ·
I have a 2006 and my issues are similar to several others but still unique. My wife informs me that when she was sitting at a stop light she says the engine acts like its going to die and the lights dim. So I drive it a cpl days and nothing. I took it to Auto Zone to see if any Engine codes were stored and "no codes". Finally it happened for me. I was sitting still and the engine RPM's dropped to 3-400. The lights dimmed. The Voltage gage showed 9.5 -10. The motor was NOT missing. It was running smooth. Weird.

I have a new battery installed. I put a voltage meter on the battery and was messing around turning things on and off... The normal reading with low "draw" was 13.9 - 14.1. I then turned EVERYTHING on I could and the idle dropped low again. The test reading was all over the place. Constantly moving from 13.75, 3, 10, 0.22, 5, etc. It bounced all over. So I thought alternator. So I went back to Auto Zone and had them run Diagnostic. The Alternator passed all tests. Weird

Now I am confused. I have no issues if I am just running "normally". Lights, radio, and heat on low ( 1 or 2) however if I turn on the heat or defrost to 4 or 5 when idle ling at light then it will drop down again and act like it wants to die.

I don't have the money to throw parts at it. I am not trying to lead anyone to say it was the alternator... but I'm open to suggestions.

BTW My TB has the same whine as the rest. Mine sounds like it is on the right side... I'm again thinking alternator...Yes the whine is RPM controlled.

Pep Boys says they will test the alternator for free if I take it off, but want $25 to test it on. It doesn't seem that easy to take off. I have basic to moderate skills.

Does this sound like anything to the Masters on here?

Mileage is at 110K if that matters. Battery is less than 2 wks old. Just replaced original battery due to cold temps.
 

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2002 chevy trailblazer_ltz
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There have been reports of members having problems after battery changes, but i'm not sure that's your problem. If the battery was changed fairly quickly (like maybe 10 minutes from cables off to cables on), the PCM may have become "confused".

IMO, I would look on this forum for the thread for cleaning the throttle body, which may be part of the problem.

Do that, which includes disconnecting the battery for 35-45 minutes. The throttle body will be clean, the PCM will be off battery long enough so it will correctly re-set to the factory defaults, and hopefully, run smoothly after a few drives around town.
 

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2004 buick rainier
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BTW My TB has the same whine as the rest. Mine sounds like it is on the right side... I'm again thinking alternator...Yes the whine is RPM controlled.

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Ok, my guess on this one is the belt IDLER pulley bearing going bad....
__________________________________________________________


The electrical problem .....it only happens when you turn FAN speed on high?
 

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2006 chevy trailblazer_ls
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I've also seen folks here having trouble with the truck running poorly after a battery change. Turned out in several cases to be the throttle body was dirty. As you drive and the throttle body starts to get dirty, the computer adjusts air/fuel to maintain the correct idle. Then you disconnect the battery and it forgets, so it goes back to stock, but the throttle body is still very dirty. Thats where I'd start, it only costs you some time and the price of a spray can of cleaner. Look up the how tos on here.

As for the whine, sounds like the ever so common idler pulley. They are cheap and easy to change, might want to start there
 

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2006 chevy trailblazer_ls_ext
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Discussion Starter · #5 · (Edited)
I was thinking about cleaning the TB, but my reasoning for putting that off (I actually looked up the thread and bought the cleaner) was that the engine was running smoothly just at a low RPM. I was thinking that if the TB was dirty or sticking then it would idle rough or would do this more often.

Yes the only time I have noticed this was if the heater or defroster is on 4/5 or 5/5. Otherwise it runs smooth. No drop in RPM's or noticeable on the voltage gage.

About the whine... the idler pulley is on the left side. I was considering replacing it if I had to remove the alternator, just do to the fairly inexpensive price.

I did investigate this once before. The only pulley that had any "play" was the water pump. I replaced this and NOPE... it was still there.

I also read the thread about removing some of the power steering fluid and replacing with Lucas Stabilizer. I am a Lucas Fan so I am also going to try this.

Oh yeah, the battery replacement... I took the old battery with me to Auto Zone and had it checked... yes it was bad... 5 years old... so I bought a new one and total time off cables.... about 1 hour.
 

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2006 chevy trailblazer_ls_ext
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Discussion Starter · #6 ·
OK so this morning it is 10 degrees outside and the TB is covered in snow. I start it and let it run 15 minutes before leaving. Defroster on 5/5, rear window defroster on, rear heat on 3/3. After 15 minutes of idle ling I leave. I turn the defroster to floor and defroster and turn down to 3/5. I drove 1 hour south with ZERO issues. Not one single time did the idle go low. When I got into town and drove threw a cpl lights until I got home... Nothing.

So now I'm not thinking the alternator... Its so inconsistant.....

Anybody got ideas??
 

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Discussion Starter · #7 ·
UPDATE... So I went out to run a cpl errands and I am frustrated. I was sitting at a redlight, I turned everything on: lights, heater on 5/5, rear heat 3/3, radio, everything I could yep.... Idle dropped down low, gages dropped, lights dimmed.

I checked things by turning 1 item off at a time to see if one particular item made a difference. By turning off 1 item the idle would correct itself. It didnt matter which item as long as turned something off.

So now I am back to thinking its alternator.

Im taking it off on friday and then to an "old alternator repairman, friend of a friend" sounds like a voodoo man if you ask me. Hope this works

I'm definitely open to suggestions or ideas before I do this...
 

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2003 chevy trailblazer_lt_ext
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You shoul tell him why.:)iagree: With your post)

You could always do the Big 3 (or 4), and upgrade some of your wiring between the alternator, battery and ground. That may help you a bit when your load demand is maxed like that. TV Vendor Jetttstream has some new stock if you're interested.

Big 3 kits with extra ground (4 cables) IN STOCK[/QUOTE
Because it could be due to High draw with the oem cables not being able to handle the amount of amperage being required to run everything. So the higher gauge wire in the kits helps to handle the extra load
 

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2006 chevy trailblazer_ls_ext
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Discussion Starter · #10 ·
well new update... I have removed some of the power steering fluid an added 12 oz of Lucas to the pump and .... Still the whine that drives me freaking crazy....

As the for Big 3. I am having trouble understanding the logic behind why I would need this. I have not added anything. There is not a major stereo or other major add other than factory equipment. Also why does it "repair" itself when I press on the gas pedal?

I have tried many many scenarios to find the culprit of something that might be an extra issue... with all the lights on, the heater on high, the rear heat on high, radio....etc I turned off everything separately and found that nothing separately caused an issue.

Anymore ideas...

Need help.
 

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2006 chevy trailblazer_ls
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Sounds to me like you are fairly convinced its the alt, so I'd say you need to get that alt tested. If thats the problem, then we're done here, if not, then you may need to try some or even one of the suggestions people have given
 

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2005 chevy
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You said you got your alternator tested, and it passed, so that kinda rules that out. If you only have the problem at idle, and with all your accessories maxed, then that tells me the load demanded is not being met. Next culprit after the alternator would be the cables supplying the power to each of those 'starving' accessories.

So it's not necessarily that you've added anything to your electrical system that has a huge demand, but there may be an issue with your existing wiring. Something loose, or some corrosion somewhere maybe. :undecided
 

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2004 gmc
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The idle should ALWAYS be rock solid at 600-625 RPM. Any time it dips below that when a load gets added, whether it's from the alternator or the AC compressor, the throttle body should instantly compensate. If the RPM dips to 500 or 550, and this is a lot easier to see on a scangauge or scan tool than the tach, then the alternator isn't going to keep up and stay in voltage regulation around 14V. Then the voltage will dip to whatever the battery can put out, like 12.1 to 12.5.

But my money is on a dirty throttle body when the idle dips, unless you have a true misfire. But misfires are usually bad all the time and then you get a flashing SES light, or bad for a short enough time that you get a P030X code for an identified misfire.
 

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2003 chevy trailblazer_lt_ext
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Think it through

well new update... I have removed some of the power steering fluid an added 12 oz of Lucas to the pump and .... Still the whine that drives me freaking crazy....

As the for Big 3. I am having trouble understanding the logic behind why I would need this. I have not added anything. There is not a major stereo or other major add other than factory equipment. Also why does it "repair" itself when I press on the gas pedal?

I have tried many many scenarios to find the culprit of something that might be an extra issue... with all the lights on, the heater on high, the rear heat on high, radio....etc I turned off everything separately and found that nothing separately caused an issue.

Anymore ideas...

Need help.
Higher rpm more amps produced if the load is high the oem wires may not carry enough therefore accessories pull down the rpm unless you add more throttle and even then the wire may not carry it unless you go to larger wire too
 

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2004 gmc
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Higher rpm more amps produced
Well, actually, unless the alternator is spinning fast enough, it may not put out enough voltage to get its internal regulator to run. If the alternator isn't in voltage regulation mode, its output collapses and only the battery is left to supply the load at its lower voltage. I think this happens around 500 RPM.
if the load is high the oem wires may not carry enough
Well, actually, amps will always get through the wiring (unless they or the fuse fails). What happens is that excessive current causes a voltage drop on the wires, so not all of the voltage gets to the load, and then the voltage at the load droops, and then you notice the dimming.
therefore accessories pull down the rpm unless you add more throttle
Sorry, this isn't the way the vehicle is supposed to work unless the throttle body is dirty/sticky. Additional current load on the alternator makes it drag on the serpentine belt more, and that additional mechanical load tries to slow the engine down but the PCM notices instantly and opens the stepper motor in the throttle body, adds fuel by increasing the injector pulse width, and essentially steps on the throttle for you to get the RPM back up to the 600 RPM target. Should happen faster than a human can deal with it or even see it on the tach.
and even then the wire may not carry it unless you go to larger wire too
Wires carry current just fine from one end to the other, but they do steal some of the voltage along the way and that's why larger wire can help if everything else is equal. Distinguishing voltage from current is an essential piece of engineering training, and I give those kind of classes so I'm just a tiny bit anal about the details. Sorry. ;)
 

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Discussion Starter · #17 ·
SBUBandit- Sounds to me like you are fairly convinced its the alt, so I'd say you need to get that alt tested. If thats the problem, then we're done here, if not, then you may need to try some or even one of the suggestions people have given....

I am NOT convinced of anything other than the fact that my Trailblazer is running like crap, some of the time. If ONE item seemed to make a significant difference I would try to repair or replace that item. I cannot afford to simply throw money or parts at this thing and hope for the best.

Roadie - Sorry, this isn't the way the vehicle is supposed to work unless the throttle body is dirty/sticky. Additional current load on the alternator makes it drag on the serpentine belt more, and that additional mechanical load tries to slow the engine down but the PCM notices instantly and opens the stepper motor in the throttle body, adds fuel by increasing the injector pulse width, and essentially steps on the throttle for you to get the RPM back up to the 600 RPM target. Should happen faster than a human can deal with it or even see it on the tach.

This makes a little more sense to me than anything else. I can understand that the Throttle Body may have carbon build up or something causing it to react or behave poorly. I will clean this on Thursday this week and report back and let everyone know.

I want to thank those of you that provided a suggestion. I may not have tried them all but I have at least considered them and tried to rationally apply them to my situation. I thought the purpose of this board was to share helpful hints and trade secrets so we all to have to experience the same nightmares. It sounds to me that Chevrolet has certainly made a vehicle that has "personality" to say the least. I have read several posts about RPM's dropping (all of them with subtle differences though), many posts about the "whine" from the front end... Many suggestions offered that run the gauntlet of price range, and many many more.

I have used the forum before when I had to change a wheel hub and found this place to be not only helpful in directions and hints for changing the hub but also the water pump that my Father in Law decided to "help" me with because he was convinced that the front end whine was from that. (that is a funny story in itself because he had taken so much of the front end apart I was very close to a sandblaster and painter.. lol I had to put it all back together before I was able to change the pump. ) BTW of course it did not fix the whine.

Thursday I also plan to change the idler pulley. It is a fairly inexpensive mod and with all the luck it will work,end this silly electrical whine and I can finally give this back to my wife to drive.

Thanks again for everyones help.
 

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2006 chevy trailblazer_lt
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My 06 had the exact same issues you described in your first post; cleaned the throttle body and it cleared right up. As Roadie described mine was dropping below 500rpm at idle and that was causing the lights the dim at night. Since cleaning the throttle body the idle is rock solid on 600rpm.
BTW, my mileage is 96k.
 

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2004 chevy trailblazer_lt
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Stalling

If you want to try to rule out the throttle body, try adding some "Sea Foam" additive to your fuel tank. It will clean things up a bit. Probably not nearly as well as a physical cleaning. But, for $8.00 it is worth a try.
 

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2004 gmc
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Fuel gets injected way past the throttle body butterfly valve. That can't work. Sorry.

Good for a cylinder cleaning, but the "suck it up by the brake booster hose, then turn the engine off for a while to let it work" seems better.

And you get a WONDERFUL smoke show for the neighbors. (I usually do my Seafoaming in the desert when I'm alone for 10 miles.)
 
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