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2004 gmc envoy
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Discussion Starter · #1 · (Edited)
2004 gmc envoy won't stay running.. keeps throwing out TPS codes yet I have purchased a new one. It starts and runs as long as you are parked. But if you drive it it goes into limp mode every few blocks then refuses to start. I read about the p0651 code and how the TPS is on the same 5v circuit as the radiator fan and how the wiring harness gets worn and grounds to the body. Or the connector is bad. And i unplugged the fan plug and it cleared the codes. I also did a reset on the TPS after installing. I had it running for a good distance again after that but it started having tye same problem again and i had to have my fruend come and pull me back home. It seems to only do it when i let off the gas or am traveling over 20mph. Then i get "REDUCED ENGINE POWER" code on the dash and it dies on me.. i can pull over and restart it and go a few more blocks but it eventually dies after about the 3rd time restating.. im just so damn lost.. i have a decent OBD scanner and i cant pinpoint the problem.. can someone please help me get this machine running again?

Also I am aware of the fuel tank pressure sensor problem.. I don't have one on it. Was under the truck and seen it wasn't there. Mysterious disappearing sensors..
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2002 chevy trailblazer_lt
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A code is the STARTING POINT of troubleshooting not the end point. It does not say a particular part has failed, it merely tells you where to begin your logical investigation into the cause of the issue.

You have done some research by reading others posts that are similar to your issue and that is a start.

You will need to identify the specific code by the actual code number, not just a "code for the TPS".

There are several codes associated with the TPS and each one is different and will involve diifferent diagnostic troubleshooting procedures.

BTW, the fuel tank vapor pressure sensor is generally on TOP of the fuel tank and is often not visible.
 

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2002 chevy trailblazer_lt
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Looking briefly at your list of codes I would start by checking live data for the #2 5 volt reference circuit and see if it is stable.

If possible view this circuit voltage while checking out all the 5 volt reference #2 wiring and components. Watch for sudden dropouts of the voltage.

If it is an intermittent short, which seems to be the case here the voltage may read proper at first but road bumps etc may cause a wire with worn insulation to rub a ground point somewhere.
 

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'05 TB 4.2 EXT
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I went through this same problem for a couple of years --- keeping a cheap scanner wrapped around the steering column for when the REP and CEL came on. I got pretty good at dumping the code and driving on without losing more than a couple of MPH.

▬ I bought a two-channel oscilloscope to test the Null of the twin potentiometers that are on the throttle pedal assembly.​
▬ I looked for drop-outs and never found any --- but I can sure tell you how to test for them if you wanna.​

Anyway --- I finally had a malfunction in my fan clutch where it locked on and didn't release for an hour or so, and now I'm waiting for some decent weather to change it out for a new clutch assembly.

Your problem may or may not be the same as mine -- but you've gotta bug it out thoroughly --- or you'll throw tons of money at it just guessing --- and like chem_man said --- don't get froggy and start ripping parts out/off and installing new ones.

PS you better read up on the dual potentiometers on that throttle!
 

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2004 chevy trailblazer_lt
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TJBaker is the one who said not to start replacing parts willy-nilly, not me, but I agree with him fully!

DIAGNOSE, DIAGNOSE, DIAGNOSE.
 

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2004 chevy trailblazer_lt
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DO NOT DISCONNECT THE BATTERY - REMOVE THE APPROPRIATE FUSE(S).

Why?

Because when you reconnect the battery, the HVAC actuators inside of the dash are commanded to run a recalibration procedure which stresses the old brittle plastic gears inside the actuators and the brittle plastic gears break and leaves you unable to control where the air comes out, or control the temperature of the air, etc. Replacing at least one of them literally requires the removal of the entire dash! So, if you ever need to actually disconnect the battery, such as in the case of needing to install a new battery, be sure and use some kind of Keep Memory Alive (KAM) device to avoid the HVAC actuator recalibration routine.
 

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2004 gmc envoy
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Discussion Starter · #8 ·
I have disconnected the battery many times and that would explain the constant clicking noise behind the - every time I start it and I couldn't find a response or a cause for that but everything you said just made sense and put it clearly for me and I have already tried replacing the throttle body brand new and it didn't fix nothing so I took it back and got a refund Didn't went to this place called RNR sales in Connersville and ripped one off an old trailblazer and put it on and it's is still throwing the same codes We're starting next? Should I try unplugging the fan clutch? My live data doesn't show the barometer jumping when it spikes and I'm not sure what code in the live data represents the 5 V circuit because it doesn't state it clearly. And I do research every P0 code where P1 code I get and look for calls in effect on each of them and every code I get all points toThe truck acting the way it does so it's like they are all working together and also against me. My skin tool has a battery an alternator test function and it told me the alternator is putting out Too high of an outputAnd also said that my battery was bad. And keeping the scant tool hooked up to the OVD port and quickly clearing the Codes when the reduced engine power light comes on really works? Because if so that's my saving graceAnd I will actually be able to drive it down the road it seems like it's been too long since I could do that. And also I have a 2000 W amplifier that keeps blowing the inline fuse and I disconnected it from the amplifier and it didn't blow the fuse so does anybody know anything about amplifiers and diagnosing what could possibly have caused it to blow the inline every time it's connected? Should I take it apart and see if the inside are fried? None of the fuses on the amp itself are blown though
 

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2004 gmc envoy
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Discussion Starter · #9 ·
Also sometimes when I go to turn the Ignition on I get the unknown driver's messand in order to fix that I have to unplug the negative terminal on my battery for a few seconds and then plug it in and then after that I get the driver one message
 

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2004 chevy trailblazer_lt
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I for one do not have a clue as to what information you are attempting to convey to us other than:

1) You now know that it is one or more HVAC actuators making noise in the dash as a result of disconnecting and reconnecting the battery

2) You put a brand new throttle body on your vehicle and it did not cure anything, nor did the junkyard part cure anything

3) You do not know how to proceed

Now for an observation I have made:

You appear to be trying to convey to us what is going on with your 2004 Envoy, but somehow your thoughts and words are first going into some kind of tumbling machine and jibberish comes out and gets typed into the computer in one extremely long paragraph comprised of two or three extremely long run-on sentences. I also know that the overwhelming majority of people from Indiana are educated quite well, and that is based on my living in Hancock County for over 4 years and interacting with my neighbors who originated from all over Indiana.

So, please try telling us what is going on with your Envoy and which engine you have in it, what all the Diagnostic Trouble Codes (DTCs) are from the OBDII system, and what modifications you have made to the Envoy such as the stereo system you have installed.

Good Luck!
 

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2004 gmc envoy
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Discussion Starter · #11 ·
i posted pictures of the codes. and it wont run more than a block without the ''recuced engine power'' light coming on and it stalling and the engine stopping. its a 2004 gmc envoy I6 4.2l and i have an aftermarket radio. its a chinese model and ive naver had problems with it. i have a 2000w amp and 1 15in subwoofer in the back. is that enough information? thats the simplest i can put it for you.
 

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'05 TB 4.2 EXT
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i posted pictures of the codes. and it wont run more than a block without the ''recuced engine power'' light coming on and it stalling and the engine stopping. its a 2004 gmc envoy I6 4.2l and i have an aftermarket radio. its a chinese model and ive naver had problems with it. i have a 2000w amp and 1 15in subwoofer in the back. is that enough information? thats the simplest i can put it for you.
STOP the 1 sentence monoparagraphs --- we don't like them and it makes YOUR thoughts incomprehensible.

Do you SEE how we write our responses?

Try it that way.
 
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