Ignition module?

Tiny
DAVISMELODY6669
  • MEMBER
  • 1997 CHEVROLET SILVERADO
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 220,000 MILES
Cam swap have fuel but no spark. Replaced ignition coil with oil pressure switch with idle control valve. The engine started strong fast idle gave it some gas to idle around 2,000 rpm's noticed the rpm were jerking down wards. I turned it off and wanted to turn it on again and nothing. Checked coil for spark and nothing. I checked the connection I have power feed but no ground with the key on. Also I have RPM reading on the gauge. Need help please.
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Friday, December 27th, 2019 AT 7:52 PM

39 Replies

Tiny
ASEMASTER6371
  • EXPERT
Good morning,

Is the distributor turning?

If you have an RPM reading, the crank sensor is sending a signal.

Roy
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Saturday, December 28th, 2019 AT 6:35 AM
Tiny
DAVISMELODY6669
  • MEMBER
Good morning, yes the distributor turns. I checked to see if the coil is throwing spark to a screw that has ground and nothing.
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Saturday, December 28th, 2019 AT 11:26 AM
Tiny
ASEMASTER6371
  • EXPERT
Okay, verify power to the positive side of the coil. If you do, then use a test light on the negative side and crank the engine. Tell me if the test light flashes.

Roy
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Saturday, December 28th, 2019 AT 11:35 AM
Tiny
DAVISMELODY6669
  • MEMBER
The clip on negative of the battery I point the test light on power feed it lights up. With key on n while cranking it flickers off and switching the clip to positive on battery I have no ground even while cranking, that's the connection for the coil. And for the ignition module I have ground and power feed using the test light.
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Saturday, December 28th, 2019 AT 11:55 AM
Tiny
ASEMASTER6371
  • EXPERT
If it is flashing then it is commanding the coil to fire. That would indicate a bad coil.

Roy
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Saturday, December 28th, 2019 AT 12:03 PM
Tiny
DAVISMELODY6669
  • MEMBER
If the power feed is flashing then it's a bad. Am I supposed to get ground from the connection too?
(The coil connection)
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Saturday, December 28th, 2019 AT 12:10 PM
Tiny
ASEMASTER6371
  • EXPERT
Forget about the ground. That is not relevant to this test. You are looking for the module turning the coil on and off.

Roy
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Saturday, December 28th, 2019 AT 12:11 PM
Tiny
DAVISMELODY6669
  • MEMBER
Okay with a charged battery I'ma do the test light on the power feed connection of the coil while cranking if it flickers means to swap out the bad coil right?
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Saturday, December 28th, 2019 AT 12:48 PM
Tiny
ASEMASTER6371
  • EXPERT
Correct.

Roy
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Saturday, December 28th, 2019 AT 1:04 PM
Tiny
DAVISMELODY6669
  • MEMBER
Doesn't flicker just gets little dim while cranking and I lost rpm signal.
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Sunday, December 29th, 2019 AT 3:23 PM
Tiny
ASEMASTER6371
  • EXPERT
Okay, then replace the module back by the coil.

Roy
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Sunday, December 29th, 2019 AT 4:09 PM
Tiny
DAVISMELODY6669
  • MEMBER
Do I replace both?
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Sunday, December 29th, 2019 AT 6:41 PM
Tiny
ASEMASTER6371
  • EXPERT
Just the module.

Roy
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Monday, December 30th, 2019 AT 4:48 AM
Tiny
DAVISMELODY6669
  • MEMBER
The ecm didnt have good ground
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Thursday, January 9th, 2020 AT 1:28 PM
Tiny
ASEMASTER6371
  • EXPERT
That is odd. The ECM controls fuel. Spark is not controlled by the ECM. It is an independent system.

Roy
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Thursday, January 9th, 2020 AT 1:36 PM
Tiny
JOSHBALLARD33
  • MEMBER
  • 1996 CHEVROLET SILVERADO
  • 63,880 MILES
I got a 1996 chevy silverado that is getting a sporadic spark from the cap. Replaced the cap and rotor cause they were bad. Is it the ignition module or coil?
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Sunday, February 7th, 2021 AT 9:15 AM (Merged)
Tiny
HMAC300
  • EXPERT
Scan for codes and check fuel pressure first. It could be a crank or cam sensor as well
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Sunday, February 7th, 2021 AT 9:15 AM (Merged)
Tiny
JOSHBALLARD33
  • MEMBER
Fuel pressure is great only engine code was p0300 generic engine miss
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Sunday, February 7th, 2021 AT 9:15 AM (Merged)
Tiny
HMAC300
  • EXPERT
What is/was fuel pressure? It should be 60-66 psi, then check compression as well as for vacuum leak and what engine is it?It can also be a bad injector
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Sunday, February 7th, 2021 AT 9:15 AM (Merged)
Tiny
JOSHBALLARD33
  • MEMBER
The fuel pressure with key on was at 50 and stayed there my good friend that a mechanic said that was good. It 5.7 vortec no vacuum leaks. The bad thing is the truck has 63000 miles and gets driven maybe twice a month looks like it came right off the show room from 1996. But if your saying pressure should be 60 to 66 then that would make sense because I thought it was the pump because she started having hard starts and then nothing thats why I check pump for pressure but make be he gave me the wrong psi
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Sunday, February 7th, 2021 AT 9:15 AM (Merged)

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