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No spark, cranks but will not start

Tiny
BRIAN567
  • MEMBER
  • 1997 GMC JIMMY
  • 4.3L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 143,000 MILES
My vehicle shut off while driving the other day. It cranks but does not start. Battery is perfect. Dashboard gauges will not move at all and will not shift out of park.
Friday, October 26th, 2018 AT 1:05 PM

48 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good afternoon.

Did you check for power to the coil?

See if you have voltage to the positive side of the coil with the key on.

Did you verify fuel pressure as well?

I attached a wire diagram for you. Check the pink wire to the coil and the module with the key on.

Roy
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Friday, October 26th, 2018 AT 1:37 PM
Tiny
BRIAN567
  • MEMBER
  • 26 POSTS
We did a spark plug test. There is no spark at all. We are going to try changing the ignition coil and see if that works. We just do not understand why the dashboard gauges do not work and why it will not shift out of park.
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Friday, October 26th, 2018 AT 1:42 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Before throwing parts at it, lets do some diagnostics.

That is why I asked you to check for voltage at the coil and the module.

Roy
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Friday, October 26th, 2018 AT 1:44 PM
Tiny
BRIAN567
  • MEMBER
  • 26 POSTS
Well there is no spark at all when we did the spark plug test using a brand new spark plug. So I am assuming it is not getting any power to the ignition. I mean I never heard of a vehicle that would not go out of park when you turn the key. That makes no sense.
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Friday, October 26th, 2018 AT 1:52 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
And I agree. That is why it makes no sense throwing parts at it.

Check all your fuses for power on both sides with the key on.

The ignition switch is common to all these issues but we need to do checks to confirm.

Roy
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Friday, October 26th, 2018 AT 1:58 PM
Tiny
BRIAN567
  • MEMBER
  • 26 POSTS
We checked all fuses and relays. Nothing bad there. However, I do know that for about a month my battery gauge always read 10 volts when you turn the key without starting the engine. I do not know if that is relevant or not.
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Friday, October 26th, 2018 AT 2:04 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
10 volts indicates a dead battery. Nothing will work with that voltage.

When you checked the fuses, did you test for power to the fuses?

Roy
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Friday, October 26th, 2018 AT 2:21 PM
Tiny
BRIAN567
  • MEMBER
  • 26 POSTS
Well we out the new ignition coil on and it started but after we shut it off it would not start up again. Even with the battery fully charged. So we tried disconnecting the ECM computer and the battery for about two minutes. Hooked them both back up and it started up again but after we shut it off it would not start back up so I am guessing either the ECM computer is bad or something is bad in my vehicle that is causing the ECM computer to shut down power to the vehicle.
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Friday, October 26th, 2018 AT 5:07 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Okay,

Again, you need to do voltage checks as I suggested three times. You seem to be avoiding this. If you want me to help you, I need information.

Otherwise, you will be throwing parts at this until you stumble across the issue. That is a waste of time and money.

Let me know if you can do the checks I suggested.

Roy
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Friday, October 26th, 2018 AT 5:15 PM
Tiny
BRIAN567
  • MEMBER
  • 26 POSTS
It is running about 14 volts through the engine. There is no loose connections as far as I can tell but I am going to try checking the ECM plugs. Maybe there is a short that I am not seeing. Just does not make sense that it started after we installed the ignition coil and then shut off again.
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Saturday, October 27th, 2018 AT 7:32 AM
Tiny
BRIAN567
  • MEMBER
  • 26 POSTS
So with that done the only other thing I can think of is that either the ECM is fried or therei s some kind of security thing going on in there that the ECM is telling the engine to shut down. I cannot reprogram the ECM because I am not a mechanic so I do not know.
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Saturday, October 27th, 2018 AT 7:40 AM
Tiny
BRIAN567
  • MEMBER
  • 26 POSTS
Also, the fact that you cannot shift it out of park with the key turned tells me that there is a security switch engaged. I just do not understand. I went through every possible thing. It has to be the computer. I just do not know anything about ECM programming.
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Saturday, October 27th, 2018 AT 8:36 AM
Tiny
ASEMASTER6371
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I asked for specific voltage readings at specific points.

14 volts through the system tells me nothing at all.

Roy
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Saturday, October 27th, 2018 AT 6:15 PM
Tiny
BRIAN567
  • MEMBER
  • 26 POSTS
Oh yeah we did that a longtime ago. That is fine. Someone told me try replacing your cam position sensor but that cannot be it because it started up after we replaced the ignition coil.
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Sunday, October 28th, 2018 AT 10:08 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
If you want me to help I need all the information I request.
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Sunday, October 28th, 2018 AT 10:34 AM
Tiny
BRIAN567
  • MEMBER
  • 26 POSTS
I understand that, but how can it be a voltage issue if it started up after we put in a new ignition coil? We tested every part of the engine for voltage and it was fine. We did not get spark before putting in the ignition coil but got spark after. It is still giving off spark as we speak. Just something is not allowing the ignition coil and ignition to let the engine start up. When we took out the old ignition coil we noticed it rattled a lot when you shake it so it was definitely a bad ignition coil. Just do not understand why it will not start back up with the new one in.
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Sunday, October 28th, 2018 AT 10:39 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
You are not understanding. Your lack of information does not allow me to help you.

I need the voltage when it will not start at the module and at the coil positive.

Without that information, I cannot and will not continue.

Roy
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Sunday, October 28th, 2018 AT 12:08 PM
Tiny
BRIAN567
  • MEMBER
  • 26 POSTS
Just forget it. It is obviously the ECM. We are just going to junk it. Thanks for your time though.
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Sunday, October 28th, 2018 AT 12:10 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
No, it is not obviously the ECM without confirming it.

Your lack of doing correct diagnostics has cost you time and money when it can be something simple.

Have a great day.

Roy
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Sunday, October 28th, 2018 AT 12:13 PM
Tiny
BRIAN567
  • MEMBER
  • 26 POSTS
So it turned out being a faulty ignition switch. We removed the plastic cover under the ignition and turned the key to the on position. Then we smacked that area with a wrench and the entire dashboard cluster had power and the vehicle started right up.
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Wednesday, November 7th, 2018 AT 3:51 PM

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