Cranks no spark

Tiny
ETEC225
  • MEMBER
  • 1988 CHEVROLET 1500
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 170,000 MILES
Hi,

I have the truck listed above 350 TBI in it. I am having a problem where I am not getting spark. The engine will crank, the injectors spray fuel. It appears that I am not getting a signal to the coil. the truck is throwing code 42 and 43

Here is a list of parts I have recently replaced:

Fuel sending unit with new pump.
Fuel lines.
Fuel filter.
Spark plugs.
Plug wires.
Cap and rotor.
Ignition control module.
Ignition coil.

Here is everything that I have tried/ tested:

Checked for loose connections at the distributor, coil and ECM.
I have continuity on all four wires going from the distributor plug to the ECM plugs.
I have continuity going from the two wires at the distributor to the coil.
The coil is receiving 12 volt switched power.
The pickup coil in the distributor will produce an AC voltage when tested. (The injectors also use this signal and they are firing.)
When a test light is taped into the white wire on running from the ICM to the coil it does not flash.
I have also tried to follow this guide. http://prntscr.com/kgv0p5 see attached image
it ends up at step 4 with a ckt 424 open, faulty connections or faulty ignition module.
I have replaced the ignition module and I have continuity on that circuit.
I am at a loss with this one. Can someone please help?
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Thursday, August 9th, 2018 AT 7:06 PM

5 Replies

Tiny
KEN
  • ADMIN
I have seen this problem before, you have done most of the testing that is pointing us to a bad ECM or the power or ground circuits are not working. Here is a guide to help you test the wiring and power with grounds:

https://www.2carpros.com/articles/how-to-check-wiring

Check out the diagrams (below). Let us know what happens and please upload pictures or videos of the problem.

Cheers, Ken
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Saturday, August 11th, 2018 AT 12:56 PM
Tiny
ETEC225
  • MEMBER
Hi,
I have confirmed that I have continuity on all of my connections. I also replaced my ecm and still nothing. The coil is not receiving any switching signal.
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Wednesday, August 22nd, 2018 AT 5:55 PM
Tiny
KEN
  • ADMIN
The fact that the injectors have pulse is a good sign. Can I ask if when you replaced the distributor cap did you transfer the internal ground strap? Small metal strap under the coil?
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Thursday, August 23rd, 2018 AT 7:57 PM
Tiny
ETEC225
  • MEMBER
I did not. The coil is remote mounted on the intake manifold in front of the distributor it is not mounted in the distributor cap. The coil does have a good connection to ground. Since my last post I have replaced the connectors going to the ignition module with no luck.
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Friday, August 24th, 2018 AT 7:56 AM
Tiny
KEN
  • ADMIN
If you checked the wiring and the ECM has power and ground the only thing left is the ECM. I would try to find a used on and plug it in here is the location below.

Check out the diagrams (below). Please let us know what you find.

Cheers, Ken
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Saturday, August 25th, 2018 AT 11:39 AM

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