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GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15181
Experience:  GM Grand Master Technician 2007. 14 years experience.
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I have an 02 Trailblazer that is running rough. It is not

Customer Question

I have an 02 Trailblazer that is running rough. It is not just a rough idle it is running rough constantly. It has no stored codes. It will flash the SES light but with code reader hooked up it only gives an accelerator pedal position sensor code. I tried a new one and it did the same thing. With the scan tool it shows that my TPS is only opening up to a max of about 35%. any ideas?
Submitted: 11 months ago.
Category: Chevy
Expert:  Roy replied 11 months ago.

good afternoon my name is roy and I will assist

what was the code?? it sounds like your tps is the issue not the [edal sensor

Roy

Customer: replied 11 months ago.
I cant recall the exact code number. It threw 2 of them, both for the accelerator pedal position sensors which has now been replaced. I cleared the codes when I replaced the part. On this vehicle the TPS is built into the throttle body and I have tried a new one, and it still has the same problem. At WOT it only shows 35% with new throttle body and accelerator sensor. It also shows a pending code of P0300 but it never goes to a stored fault.
Expert:  Roy replied 11 months ago.

there are 2 tps in the system. one goes from 0-100% and the other goes from 100-0. if you replaced the throttle body, and the pedal sensor, I would inspect the wiring as common areas are by the kick panel.

the 300 code is a multiple miss fire code. it has no effect on the accelerator pedal codes

Roy

Customer: replied 11 months ago.
At idle it shows the TPS reading at 18% and runs rough. Would a faulty tps reading cause the engine to run rough and possibly cause the 300 code, because the running rough is my main concern.
Expert:  Roy replied 11 months ago.

check the connector on the tps for damaged pins and corrosion.

again, the 300 code is separate and has nothing to do with this issue

Roy

Customer: replied 11 months ago.
I checked the pins at the throttle body and the pedal. Both look fine. I could not find any noticeably damaged wires in the harness either. Could this possibly be a bad ECM?
Expert:  Roy replied 11 months ago.

no, the system is independent of the pcm. it has its own control module on the pedal sensor

Roy

Expert:  Roy replied 11 months ago.

take a look at the pin out for the pedal sensor

Roy

Customer: replied 11 months ago.
Pins look good. No bends, cracks or corrosion
Expert:  Roy replied 11 months ago.

did you check the view I sent you for all the voltages??

Roy

Customer: replied 11 months ago.
I just checked and I have a good 5 volts on both reference signal pins.
Expert:  Roy replied 11 months ago.

and the grounds and the continuity to the tps???

Roy

Customer: replied 11 months ago.
grounds are good and it has continuity
Expert:  Roy replied 11 months ago.

if all the readings are correct, the system is working correctly.

I will opt out and see if someone else can help you.

Roy

Expert:  Tool Hut replied 11 months ago.

Hi, My Name is ***** ***** for posting your question to just answer. I am a independent contractor for just answer, and ASE Certified Master Auto Technician with 20 years experience. I am confident we can resolve your problem together.Please remember I don't know your skill level. I can't see, smell, hear, or touch the vehicle. It may take a few back and forth replies to get to a satisfactory resolution.I also try to give all of the information you may need expecting a positive rating. I am not compensated for my time until you leave a positive rating.

I have read the thread above.

IS the check engine light flashing all of the time?

Expert:  Tool Hut replied 11 months ago.

Do you still need help?

Customer: replied 11 months ago.
I'm very sorry I didn't see your response until now. I no longer need help. Thank you

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