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Pete
Pete, Auto Service Technician
Category: Chevy
Satisfied Customers: 29110
Experience:  14 years GM dealer Technician.
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How can I tell if I have a bad ecm. Replaced throttel body

Customer Question

How can I tell if I have a bad ecm. Replaced throttel body sensor and gas pedal sensor and it wont start. The butterfly valve will open and close as you work the pedal.
Submitted: 2 months ago.
Category: Chevy
Expert:  Pete replied 2 months ago.

Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay.

Is the starter engaging to crank over the engine at all with this issue here?

Have you had fault codes checked/read out at all?

Has anything been checked, tested or replaced to try and locate and repair this fault already besides what is listed above?

If you can give me a little more info on exactly what is happening this will help as well here.

Let me know so we can continue,thanks Pete.

Customer: replied 2 months ago.
had a reduced power error. after a few trips it died. I did get this message months ago but it cleared itselef. Had code about the tbs. A p2176 also. Now I have no codes and it will turn over fine but wont start. Have been trying to get relearn info for the new pedal and tbs but cant find it for a dead engin. When I left the battery cables off over night i did hear the throttel body cycle about three times.
Customer: replied 2 months ago.
had a reduced power error. after a few trips it died. I did get this message months ago but it cleared itselef. Had code about the tbs. A p2176 also. Now I have no codes and it will turn over fine but wont start. Have been trying to get relearn info for the new pedal and tbs but cant find it for a dead engin. When I left the battery cables off over night i did hear the throttel body cycled about three times.
Customer: replied 2 months ago.
no thanks on the call
Expert:  Pete replied 2 months ago.

I apologize for the delay,Reviewing your info now.

Expert:  Pete replied 2 months ago.

No problem on the phone call.That is an automated feature the web site offers customers.

Is your security light staying on steady or flashing at all on the dash when you try and start and when it will not start you just release the key?It may say security or may be a picture of a car with a lock across it.

Let me know,thanks Pete

Customer: replied 2 months ago.
the llight of a padlock would alway come on but go off when the engin sstarts. I did have the dash say sevice anti theft system when we did try to program a ke but I am not getting that now.
Expert:  Pete replied 2 months ago.

Is the padlock light on steady now or flashing at all when you try and start it and when it wont start you just let go of the key?

Customer: replied 2 months ago.
Not flashing. I do let go of the key and the stater keeps running for about 4 seconds
Expert:  Pete replied 2 months ago.

Did you check to see if you had blown any fuses with this fault here at all?

Let me know,thanks Pete.

Customer: replied 2 months ago.
Yea fuel pump fuse was shot. rplaced it. Will start now but just for a few seconds. getting p0122 and po223
Expert:  Pete replied 2 months ago.

O.k.,now if you clear these codes do they come right back again?

Customer: replied 2 months ago.
did get the codes back but they are gone now. The 122 was in permanent stored codes but is gone after a few atempepted starts. got a airbag code but that is where I got the fule pump fuse from.
Expert:  Pete replied 2 months ago.

Have you tested fuel rail pressure at all?

Customer: replied 2 months ago.
No.This might take a minute. Ill be back.
Expert:  Pete replied 2 months ago.

No problem

Customer: replied 2 months ago.
Sorry for the delay. Cant find my fuel pressure tool. I am going to go bang my head on a wall then get back to you latter. Dont expect you to wait. Might be a couple hours.
Expert:  Pete replied 2 months ago.

No problem.

Your fuel pressure needs to be between 59 and 62 psi.If it is any lower then this then the power and ground need tested at the fuel pump.You need 12 volts on the gray wire and ground on the black wire.The 12 volts will come with key on or cranking over the engine.If you have these signals then the pump needs replaced.If this is all found o.k. let me know.

If I do not reply right away when you respond again I will as soon as I can.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service,your 5 star rating is appreciated ( should be a link to click on here or above).You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 2 months ago.
fuel pressure is fine.
Expert:  Pete replied 2 months ago.

I apologize for the delay as I was not able to get back here yesterday.

Are codes p0122 and po223 still setting?

Let me know,thanks Pete

Customer: replied 2 months ago.
No
Expert:  Pete replied 2 months ago.

Have you tested for spark at at least 3 spark plugs?

Have you tested fuel injector pulses?

Customer: replied 2 months ago.
All good. It will start and run for a few seconds.
Customer: replied 2 months ago.
I think it needs to learn the new parts
Expert:  Pete replied 2 months ago.

Here is the manual relearn

Throttle Learn

Reset Procedure (Performed after the throttle body is cleaned or replaced)
1. Ignition ON, engine OFF, perform the Idle Learn Reset in Module Setup with a scan tool.
2. Start the engine and monitor the TB Idle Airflow Compensation parameter. The TB Idle Airflow Compensation value should equal 0 percent and the engine should be idling at a normal idle speed.
3. Clear the DTCs and return to the diagnostic that referred you here.

If this does not work let me know.

Let me know if you need anything else and feel free to rate my help here or above ( should be a link to click on ) as this is how I receive credit for my time,this can be done at any time and you can still come back here and reply if needed.Your 5 star rating is appreciated

Thanks Pete