Chevy

Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP

Ask an Expert,
Get an Answer ASAP!

2011 impala 3.5L & 2007 trailblazer 4.2L exibiting the same…

Customer Question
2011 impala 3.5L &...

2011 impala 3.5L & 2007 trailblazer 4.2L exibiting the same symptoms - can not control throttle body. Changed throttle body & PCM with no results. Scanned PCM, APP is present but no throttle plate movement on either vehicle. APP movement is being picked up by PCM - checked wiring OK - Can move throttled plate by hand & see movement on scanner WHAT's WRONG

Mechanic's Assistant: Have you checked all the fuses? Do you have a wiring diagram?

Yes

Mechanic's Assistant: Are you fixing your Trailblazer yourself? What have you tried so far?

Changed throttle body & PCM, checked wiring for continuity OK

Mechanic's Assistant: Anything else you want the mechanic to know before I connect you?

Can't get the throttle to relearn because I can't control RPM's

Submitted: 7 months ago.Category: Chevy
Show More
Show Less
Ask Your Own Chevy Question
Answered in 4 minutes by:
12/14/2017
Chevy Mechanic: Roy, import/domestic specialest replied 7 months ago
Roy
Roy, import/domestic specialest
Category: Chevy
Satisfied Customers: 7,728
Experience: ASE master tech for 40 years
Verified

hello, my name is ***** ***** I will be glad to assist you. please allow me a couple of minutes to gather some basic info.

Roy

Ask Your Own Chevy Question
Chevy Mechanic: Roy, import/domestic specialest replied 7 months ago

ok

did you change the pedal assembly?? this is what controls the throttle body movement. the pcm may see the tps working but the pedal module controls the commands.

Roy

Ask Your Own Chevy Question
Customer reply replied 7 months ago
Even if i see movement on my scanner that the pedal is moving
Chevy Mechanic: Roy, import/domestic specialest replied 7 months ago

your seeing a reading for the tps sensor voltage change on the throttle body.

Roy

Ask Your Own Chevy Question
Customer reply replied 7 months ago
I see sensor voltage change when i move the throttle plate manually, i see pedal voltage change on my scanner as i depress the pedal - when i press the pedal no change at throttle body
Chevy Mechanic: Roy, import/domestic specialest replied 7 months ago

I see what you mean but the module is not commanding the motor to open.

Roy

Ask Your Own Chevy Question
Customer reply replied 7 months ago
Exactly, I've actually had a mobile programmer try to reprogram the throttle body with no results - he suggested a wiring problem but i have continuity with all wiring
Chevy Mechanic: Roy, import/domestic specialest replied 7 months ago

its not the throttle body. the control module is part of the inside pedal assembly.

Roy

Ask Your Own Chevy Question
Customer reply replied 7 months ago
That might explain the no throttle movement but it doesn't explain the erratic idle
Chevy Mechanic: Roy, import/domestic specialest replied 7 months ago

2 separate issues. nothing listed in your post for a rough idle

Roy

Ask Your Own Chevy Question
Customer reply replied 7 months ago
All these problems started at the same time, started vehicle it an rough and could not accelerate, changed throttle body first, then PCM
Chevy Mechanic: Roy, import/domestic specialest replied 7 months ago

get the throttle body resolved first and then drive it to see if the rough idle still exists. the module will position the plate correctly to adjust idle speed and smooth.

otherwise there is another issue. first things first

Roy

Ask Your Own Chevy Question
Customer reply replied 7 months ago
i'll give a shot will get back tomorrow to let you know how it goes
Chevy Mechanic: Roy, import/domestic specialest replied 7 months ago

ok

Please take a moment and rate my service 3 stars or better. that is the only way the site will pay me for my efforts.

Roy

Ask Your Own Chevy Question
Customer reply replied 7 months ago
I'm guessing it's 3 out of 5 stars - it was worth at least 3 stars - if it works i'll give you 5 stars but i won't get any parts until tomorrow - worth the conversation - thanks
Chevy Mechanic: Roy, import/domestic specialest replied 7 months ago

your welcome

when you rate hit the number of stars at the top of the page

Roy

Ask Your Own Chevy Question
Chevy Mechanic: Roy, import/domestic specialest replied 7 months ago

any update???

Ask Your Own Chevy Question
Customer reply replied 7 months ago
OK tried the accelerator pedal - it did not wok
Customer reply replied 7 months ago
the initial problem of erratic idle and unable to accelerated remains - i'm at a loss
Customer reply replied 7 months ago
roy are you there ?
Customer reply replied 7 months ago
Roy - still waiting for an answer
Chevy Mechanic: Roy, import/domestic specialest replied 7 months ago

yes, I am here. was on phone with another customer.

did you verify 5 volt reference at the app?? there are tan, white/black and gray wires. they all need 5 volts key on.

please be patient as I answering many questions.

Roy

Ask Your Own Chevy Question
Customer reply replied 7 months ago
5 volts are present and i see voltage change on my scanner as i depress the pedal
Chevy Mechanic: Roy, import/domestic specialest replied 7 months ago

ok

is there any voltage on the tan wire at the throttle body???

Ask Your Own Chevy Question
Customer reply replied 7 months ago
all 5 volt references are present
Chevy Mechanic: Roy, import/domestic specialest replied 7 months ago

no, my question was is there voltage on the tan wire at the throttle body???

what voltage do you have at the motor wires on the throttle body???

Roy

Ask Your Own Chevy Question
Customer reply replied 7 months ago
8 wires - blk/wht 0v - gry 5v - brn .245v - yel 0v - ppl 4.30v - blk 0v - blu/blk 5.0v - grn .014v that come from throttle body
Chevy Mechanic: Roy, import/domestic specialest replied 7 months ago

are you sure the blk/wht is not a white/black??? in the diagram I sent you it should have 5 volts from the pcm

Roy

Ask Your Own Chevy Question
Customer reply replied 7 months ago
i'm checking the 2007 trailblazer (the 2011 impala has the exact same problem) there is no white/black wire
Chevy Mechanic: Roy, import/domestic specialest replied 7 months ago

wish you would have told me that

let me get the info from that

Ask Your Own Chevy Question
Customer reply replied 7 months ago
we discussed this from the very beginning
Chevy Mechanic: Roy, import/domestic specialest replied 7 months ago

you listed both cars in your original not mentioning which one you were actually checking

my concern is no power to the motor wires for moving the plate. that comes directly from the pcm to the throttle body.

when you command the throttle plate open with the scan tool can you check the power on those wires???

Roy

Ask Your Own Chevy Question
Customer reply replied 7 months ago
i checked that earlier, there was no voltage change at throttle body. tried manually moving throttle plate with 12v power & ground the throttle plate moved accordingly
Chevy Mechanic: Roy, import/domestic specialest replied 7 months ago

then that tells us the pcm is not working sending the signal. thats where it comes from.

you said you verified wiring was good so that leaves only the pcm. I assume you flashed the pcm to the vin number of the truck.

Roy

Ask Your Own Chevy Question
Chevy Mechanic: Roy, import/domestic specialest replied 7 months ago

ok, then it looks like you have a bad pcm

Roy

Ask Your Own Chevy Question
Customer reply replied 7 months ago
on the impala i changed both the PCM and the throttle body with no results, i took apart the wiring harness to physically check the wiring from the PCM to the throttle body which on the 2011 impala 3.5L are basically ight next to each other and found no problems with continuity or voltage
Chevy Mechanic: Roy, import/domestic specialest replied 7 months ago

ok

Ask Your Own Chevy Question
Customer reply replied 7 months ago
Roy, any good news today ?
Chevy Mechanic: Roy, import/domestic specialest replied 7 months ago

no, I cannot continue since I am here and not there. I need to see it, touch it and test it myself in orer to resolve this. I will opt out and see if anyone else has any ideas.

Roy

Ask Your Own Chevy Question
Chevy Mechanic: Todd Audette, Chevy Technician replied 7 months ago
Todd Audette
Todd Audette, Chevy Technician
Category: Chevy
Satisfied Customers: 427
Experience: Chevrolet Technician
Verified

I can try to help you but we need to be working on 1 car at a time

Ask Your Own Chevy Question
Customer reply replied 6 months ago
which vehicle would you like to start with (2011 impala 3.5L or 2007 trailblazer 4.2L) both have the same symptoms cannot control the throttle plate with accelerator pedal or mato maximus 2.0 scanner even though voltage change while depressing pedal or manually moving throttle plate
Chevy Mechanic: Todd Audette, Chevy Technician replied 6 months ago
Impala first. I'm at work so I'll be on and off when i can. Any codes in the impala
Ask Your Own Chevy Question
Chevy Mechanic: Todd Audette, Chevy Technician replied 6 months ago
There's a 14 pin connector on the top of the drivers strut tower that goes between the accelerator pedal and ecm. Check that make sure no loose terminals, corosion etc
Ask Your Own Chevy Question
Chevy Mechanic: Todd Audette, Chevy Technician replied 6 months ago

Do you still need help or are you good

Ask Your Own Chevy Question
Customer reply replied 6 months ago
Checked connector on strut tower OK
Chevy Mechanic: Todd Audette, Chevy Technician replied 6 months ago
let me get this straight. When the car is running you have no throttle response or just when the key is in the on position
Ask Your Own Chevy Question
Customer reply replied 6 months ago
all the time
Chevy Mechanic: Todd Audette, Chevy Technician replied 6 months ago
Have you ohm tested the wires end to end from the ecm to the pedal
Ask Your Own Chevy Question
Chevy Mechanic: Lou P., ASE Certified Technician replied 6 months ago
Lou P.
Lou P., ASE Certified Technician
Category: Chevy
Satisfied Customers: 6,080
Experience: Building and driving Chevy's since I was in the womb!!!! Camaro and Corvette enthusiast, access to factory diagrams and tsb's
Verified

Hello Al, it seems you have quite the issue,

looking over the chats I know I can help, But when the techs ask you questions you do not answer them, you seem to reply with some other info that was not requested.

so I can help, I will want to start off as if you NEVER worked on the car at all.

first thing I will want to do is the 2011 impala.

start the car, use the scan tool to run the codes. report back to me the codes and we can go from there.

fixing issues like these are not complicated. but they can be if we do not stay on the same page and do things in order slowly. not to get ahead of each other and keep open clear communication.

I am willing to work with you to resolve this.

so 2011 impala, start it and press the gas pedal a few times to verify no operation and then run the codes to see what codes pop up in ALL modules., not just the ecm.,

Lou

Ask Your Own Chevy Question
Customer reply replied 6 months ago
OK lou, i'm back. scanned the 2011 impala 3.5L codes p0315, p0523, p1516, p2101, p0122, p0222, p0223 (sorry it took so long it's the holidays)
Chevy Mechanic: Lou P., ASE Certified Technician replied 6 months ago

no worries i am in the same boat :)

looking over the codes now and thanks for working with me on this.

Ask Your Own Chevy Question
Chevy Mechanic: Lou P., ASE Certified Technician replied 6 months ago

ok my man here are the code descriptions.

the important ones are pretty much all but the crank sensor one at the moment and the oil pressure one.

the codes indicate to me wiring issues.

so take a look over the info I am sending over.

we need to verify the voltages with a scan tool and meter on the physical connections.

now in my experience with all of the GM fly by wire cars the issue is one of 4 very common failures

  1. throttle body
  2. throttle body connector/terminals (napa has a repair kit)
  3. accelerator pedal
  4. accelerator pedal connector/terminals (napa as well)

so lets take a real good look at the wiring, and also the voltage.

since you have a new part (hopefully NEW GM) and not reman or used then we need to verify that the voltage is correct.

also history of how this happened would be best too.

but these codes are the money shot.

if you have any question about the testing let me know i will do what I can to advise

Lou

Ask Your Own Chevy Question
Was this answer helpful?

How JustAnswer works

step-image
Describe your issueThe assistant will guide you
step-image
Chat 1:1 with a chevy mechanicLicensed Experts are available 24/7
step-image
100% satisfaction guaranteeGet all the answers you need
Ask Lou P. Your Own Question
Lou P.
Lou P.
Lou P., ASE Certified Technician
Category: Chevy
Satisfied Customers: 6,080
6,080 Satisfied Customers
Experience: Building and driving Chevy's since I was in the womb!!!! Camaro and Corvette enthusiast, access to factory diagrams and tsb's

Lou P. is online now

A new question is answered every 9 seconds

How JustAnswer works:

  • Ask an ExpertExperts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional AnswerVia email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction GuaranteeRate the answer you receive.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money.

Todd LRochester NY

Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help.

Mary C.Freshfield, Liverpool, UK

This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!!

AlexLos Angeles, CA

Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult.

GPHesperia, CA

I couldn't be more satisfied! This is the site I will always come to when I need a second opinion.

JustinKernersville, NC

Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around.

EstherWoodstock, NY

Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know.

RobinElkton, Maryland

< Previous | Next >

Meet the Experts:

GM Tech (Cam)

GM Tech (Cam)

Chevy Technician

15,659 satisfied customers

GM Grand Master Technician 2007. 14 years experience.

Gary

Gary

Chevy Technician

9,621 satisfied customers

15 years GM master tech

Tim&#039;s Auto Repair

Tim's Auto Repair

mechanic

8,884 satisfied customers

Have owned a repair shop for 25 yrs.

Dave Nova

Dave Nova

Chevrolet Technician

7,092 satisfied customers

ASE Master Certification. GM World Class Certification

John

John

Master A.S.E Automotive technician

4,071 satisfied customers

A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician

Don - Mo Lurch

Don - Mo Lurch

Auto Mech / Electronics

2,948 satisfied customers

Chevrolet Cert., Heavy Line Mech, Race Shop Owner, Mobile Electronics.

Ron Z.

Ron Z.

- Chevy Tech -

2,822 satisfied customers

18+yrs experience. State Inspector and Chevy Diagnostics

< Previous | Next >

Related Chevy Questions
My throttle voltage never changes as the others do. stays at
my throttle b voltage never changes as the others do. stays at .999, replaced pedal and throttle body thanks hood hoppet … read more
Chad Farhat
Chad Farhat
Owner
Associate Degree
5,426 satisfied customers
I have a 2007 Chevrolet Trailblazer 4.2l the secondary air
I have a 2007 Chevrolet Trailblazer 4.2l the secondary air pump won't come on. I replaced the air pump , air solenoid, relay to the pump and relay to the air solenoid. I jumped the connecters at the p… read more
Roy
Roy
import/domestic specialest
7,728 satisfied customers
2007 CHEVY EQUINOX CLEANED THROTTLE BODY ..IDLE WENT UP..
2007 CHEVY EQUINOX CLEANED THROTTLE BODY ..IDLE WENT UP.. WHAT WOULD CAUSE THIS.. WILL A RELEARN HELP WITH SCANNER… read more
Gary
Gary
Chevy Technician
Vocational, Technical or Trade Scho
9,621 satisfied customers
Chevrolet Trailblazer LS: HAVE A 02 CHEVY TRAILBLAZER AND HAS
HAVE A 02 CHEVY TRAILBLAZER AND HAS A P1515 AND P1271 CODE A FRIEND REPLACED APP SENSOR AND THROTTLE BODY AND PERFORMED RELEARN IDLE PROCEDUR AND STILL HAS P1271 CODE WITH SERVICE ENGINE LIGHT ANF RED… read more
Gary
Gary
Chevy Technician
Vocational, Technical or Trade Scho
9,621 satisfied customers
06 Colorado 3.5 rwd DTC = p 2135, p 1516, p060E . TP and APP replaced already I cleared c
06 Colorado 3.5 rwd DTC = p 2135, p 1516, p060E . TP and APP replaced already I cleared codes and the're back again… read more
Pete
Pete
Independent Auto Technician
Vocational, Technical or Trade Scho
138 satisfied customers
Chevrolet Trailblazer LS: 2002 chey trailblazer 4.2L 2wd. cruising
2002 chey trailblazer 4.2L 2wd. cruising at 65 on cruise control /flashes reduce engine power… read more
Ironmike
Ironmike
ASE Master L1 performance ,Ford tech
Vocational, Technical or Trade Scho
1,773 satisfied customers
Chevrolet Trailblaxer: I have a 2003 trailblazer. When the
I have a 2003 trailblazer. When the car has sat over night and i start it the engine will start but the service engine light comes on and the reduce engine power light comes on. I cannot get the engin… read more
Ironmike
Ironmike
ASE Master L1 performance ,Ford tech
Vocational, Technical or Trade Scho
1,773 satisfied customers
2006 Trailblazer SS: reduced engine power..check engine..scanner
Hello, I have a 2006 Trailblazer SS and the reduced engine power, check engine and stabilitrak lights just came on today. These are the codes I was able to pull with a genesis scanner P060E and P1235.… read more
GM Tech (Cam)
GM Tech (Cam)
Chevy Technician
Vocational, Technical or Trade Scho
15,659 satisfied customers
My girlfriend has a 2007 Chevy TrialBlazer, 6cyl, 4.2L with
My girlfriend has a 2007 Chevy TrialBlazer, 6cyl, 4.2L with 56K+/-mile on it. She's had check-engine lights on for sometime and recently had the car inspected. The codes came back as P0506 and P1400. … read more
Bill
Bill
Foreman/Team Leader
Vocational, Technical or Trade Scho
593 satisfied customers
2003 Chevy trailblazer: revving..it revs to at least the 2..rpm..kicks
Why would my 2003 Chevy trailblazer with only 53000 miles on it, suddenly be revving like crazy? When I turn the key in the ignition it revs to at least the 2 on the RPM dial, and when I am driving it… read more
Matt Carey
Matt Carey
asst. manager/ lead technician
High School or GED
225 satisfied customers
2002 Trailblazer: that loses power..light comes..pedal
A friend has a 2002 Trailblazer that loses power and the Reduced Engine Power light comes on. They had analyzed, and it said replace the pedal sensor. So it was done. Didn't fix the problem. They have… read more
Tim&#039;s Auto Repair
Tim's Auto Repair
mechanic
High School or GED
8,884 satisfied customers
My 2004 Malibu Maxx has a 2135 TPS/APPS alarm. The dealer says
My 2004 Malibu Maxx has a 2135 TPS/APPS alarm. The dealer says the car doesn't have a tps connected to the throttle body. So i'm guessing i'd just have to replace the pedal position sensor right? I to… read more
goodwrench9124
goodwrench9124
Lead Tech/ Shop Leader
Vocational, Technical or Trade Scho
2,571 satisfied customers
2004 Trailblazer: Oil changes...It..000miles..Engine Soon light
I have a 2004 Trailblazer that is very well cared for. Oil changes and maintenence.It has 125,000miles on it. MY Check Engine Soon light came on. I bought a code reader and it gives me 2 codes PO106 a… read more
Shane
Shane
Vocational, Technical or Trade Scho
84 satisfied customers
Colorado: My check engine light came..vacuum leak..ac
My check engine light came on on my 04 colorado and i went to a parts house and had it checked out and they said it was a vacuum leak. also does this have anything to do with my ac?… read more
RussMasterTech
RussMasterTech
GM Service Technician
3 Years College
546 satisfied customers
I have a 2003 TrailBlazer. My service engine soon light
I have a 2003 TrailBlazer. My "service engine soon" light came on, and this time it is staying on. I have done all of the "cheap" and "easy" fixes. She has had a good tune up, new filters, etc., the l… read more
Michael Moore
Michael Moore
Team leader, bumper to bumper tech.
Associate Degree
1,323 satisfied customers
2005 chevy colorado: battery put..local shop..reduced power showed
i have a 2005 chevy calorado and i just got a new battery put in at a local shop. it was real cold this morning and on the way to work reduced power showed up on my display. could this be a cold batte… read more
John
John
Master A.S.E Automotive technician
2 YEARS COLLEGE
4,071 satisfied customers
Blazer: the car engine shouts down I used my scanner and the screen
I have a trail blazer 2002 ,the engine in the morning cheiking for 10 or more minutes , and every time I turn the air conditionig on ,the car engine shouts down I used my scanner and the screen say P0… read more
Mcgruder73
Mcgruder73
Auto Technician
Associate Degree
Gmc: map..circuit..I have already change the mass air sensor..autozone
on the gmc map baro circuit problem, I have already change the mass air sensor and the other sensor it was $60 at autozone I forget the name do you still have an answer… read more
Scott K
Scott K
Automotive Instructor
Vocational, Technical or Trade Scho
1,330 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less

Ask Your Question

x