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Pete
Pete, Technician
Category: Car
Satisfied Customers: 27537
Experience:  17 years automotive training and experience.
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2007 Envoy SLT, I have put two new ignition switches from

Customer Question

2007 Envoy SLT, I have put two new ignition switches from Oriley's in and all is good until it sits over night in the cold, then it want start again. Battery is good, everything lights up when I turn the key on except the check engine light on the left side of the cluster does not light up. (I was told that as long as that light does not come on it will not start)
I put it in a shop and he ran all the diagnostics with his equipment and found nothing, while in his shop it mysteriously started working and worked until I picked it up last night, i drove it home and it worked fine, I cranked it several times and it worked fine.
It was 11 degrees here this morning and it will not crank, again everything lights up except the check engine light on the left side of the cluster then when I move the switch to the start position, nothing happens.
JA: Does the light stay on, or does it blink?
Customer: check engine light does not come on
JA: Are you fixing your Envoy yourself? What have you tried so far?
Customer: new ignition switch (2) my mechanic ran dianostics with his equipment
JA: Anything else you want the mechanic to know before I connect you?
Customer: did you read where it works after i install a new switch till the nex morning
JA: JustAnswer.com.
Customer: ???
JA: What confuses you?
Customer: what is next
Submitted: 5 months ago.
Category: Car
Expert:  Pete replied 5 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 check engine light always off when this issue occurs here?

Let me know so we can continue,thanks Pete.

Customer: replied 5 months ago.
Expert:  Pete replied 5 months ago.

O.k.,the power and ground signals need tested at the engine computer when this occurs.if you have the correct power and ground signal but the check engine light is not on and there is a no start issue then this is the engine computer itself at fault.The engine computer controls the engine light.It should always come on every time the key is switched on.Since it is not coming on I suspect either an intermittent wiring/connection fault to the engine computer or the engine computer itself is at fault internally.Most of the time it is internal to the computer with it needing replaced.

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.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 5 months ago.
Is there a place where i can look for wireing issues should i unplug the main computer and plug it back to check for a loose connection there?
Customer: replied 5 months ago.
I am assuming I should disconnect the battery before
Expert:  Pete replied 5 months ago.

There is no common area.I would inspect the wiring running to and at the computer for any issues needing repaired or replaced.You can unplug the computer as well with the key off and check for any damaged pins in the connectors.

Let me know if you need anything else and feel free to rate my help here as this is how I receive credit for my time.Your 5 star rating is appreciated

Thanks Pete

Customer: replied 5 months ago.
On 2 occasions I have installed a new ignition switch and it would work after that until it set overnight, Can you think of a reason that that would occur?
Expert:  Pete replied 5 months ago.

I apologize for the delay.

The only thing I see here is damaged wiring or connections at the ignition switch itself or an issue with a short leading to the ignition switch causing this fault here.This would be the only other thing I can think of that can cause this here.

Thanks Pete

Customer: replied 5 months ago.
Well late yesterday I unplugged the 3 huge plugs on the main Computer there on the left side of the motor (straight 6) and inspected them, found nothing out of the ordinary. Plugged them back in and tried to crank and wow, the check engine light came on and it cranked. I thought i had found the problem. I cranked it several times last night and again this morning. Then this afternoon I tried it again and the check engine light does not come on and it will not crank. Any suggestions?
Expert:  Pete replied 5 months ago.

Since you had removed and reconnected the computer and the issue corrected itself temporarily this does sound like an internal electrical fault in the engine computer itself.It may have just been the slight movement at the computer when disconnecting and connecting it that allowed the brief start times.I have seen some computers act up like this here before and had to replace and program the computer to resolve this here.

Let me know if you need anything else and feel free to rate my help here as this is how I receive credit for my time.Your 5 star rating is appreciated

Thanks Pete

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