Codes p1275 and p1280, starts hard but will idle?

2003 CHEVROLET TRAILBLAZER
228,000 MILES • 4.2L • 6 CYL • 4WD • AUTOMATIC
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HUNTER0307
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i replaced the valve cover gasket, intake manifold gasket, throttle body gasket, cleaned throttle body while out, i actuated the throttle body by hand while cleaning, put everything back together. now it starts after the third try, it will idle at about 1,100 RPMs, no throttle response. I have p1275 and p1280 codes, check Eng and reduced power lights on. i have checked and rechecked all connections, run electrical tests, I cannot find an issue.
Aug 19, 2024 at 6:56 PM
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JACOBANDNICKOLAS
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Hi,

Both codes are related to the accelerator pedal position switch in the vehicle. Was any work done to that?

Do me a favor. I attached diagnostics for the P1280 below. I feel that code should be checked first. Take a look through the diagnostics and let me know if you are comfortable performing them.

Let me know.

Joe

See pics below.
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Aug 19, 2024 at 8:02 PM
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HUNTER0307
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No work was done to the interior at all, I have a Foxwell scan tool, I am comfortable with testing, and will get back tomorrow.
Aug 19, 2024 at 8:09 PM
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HUNTER0307
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I forgot to mention it will start and immediately stall 3 times then start and idle at 1,100 RPMs, but nothing on throttle.
Aug 19, 2024 at 9:57 PM
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HUNTER0307
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I did all the tests, then tested the to unit with an ohm meter,0.00 across all test, no response on meter when actuating throttle.
Aug 20, 2024 at 10:04 AM
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JACOBANDNICKOLAS
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Hi,

When you opened the throttle plate by hand, that may have damaged the throttle body. If you are getting no response or readings from testing, that is what it sounds like happened.

Let me know your thoughts.

Joe
Aug 20, 2024 at 5:49 PM
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HUNTER0307
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well, I replaced the throttle body with a known good one, no difference, my scanner says my throttle is not actuating, put old throttle body on another blazer and it ran perfect, I did the graph on my scanner for "absolute throttle position", got no response, flat line while i operated the throttle, I then did an ohms test on the throttle, and everything seemed good, I think i will still try replacing the throttle, still getting p1275,and p1280 codes, and refuses to reset, I have checked all vacuum hoses, wires, cant find a thing.
Aug 20, 2024 at 7:21 PM
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JACOBANDNICKOLAS
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My online manual is presently down. However, I need you to check grounds for the TB and APP. See if anything was damaged or shorted.

Let me know.

Joe
Aug 20, 2024 at 7:32 PM
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HUNTER0307
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Okay, I will get back. also, i am going to be getting my vehicle inspection license, where might i find a good source on vehicle specifications like ball joint tolerance etc., for vehicles up to 2022?
Aug 20, 2024 at 8:37 PM
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HUNTER0307
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Problem solved, thank you for all your help, attached picture of issue.
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Aug 21, 2024 at 6:58 AM
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JACOBANDNICKOLAS
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Hi,

It was a ground??? If so, I'm glad you found it. Electrical issues can be a pain. LOL

As far as your question about specifications is concerned, yes, I would be happy to get what you need. I just need you to start a new question when the topic changes or the vehicle changes. It is more helpful to others when that is done.

Here is the link to start a new one:

https://www.2carpros.com/questions/new

Regardless, I'm glad to know the problem is resolved. Take care and feel free to come back any time in the future.

Joe
Aug 21, 2024 at 7:13 PM