No signal to coil

Tiny
BIGJOHN610
  • MEMBER
  • 1991 FORD F-150
  • 5.0L
  • V8
  • 4WD
  • AUTOMATIC
  • 113,000 MILES
My truck quit running one day and would not restart. I checked fuel pressure, it was fine. I started checking for spark. No spark. Checked for signal coming into coil and there was none. I decided to replace the pickup coil, ignition module, and coil with new Motorcraft replacements. I reinstalled the distributor and coil, and checked initial timing. The truck ran great for 30 minutes, and revved up to 2,000 rpm's, battery light was flickering while this was happening, and shut off. It would not restart. Same problem, no signal to the coil. I tried unplugging the spout connector, still no signal. The next morning, it started right up and did the same thing as the day before. Any ideas? Anybody?
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Wednesday, March 13th, 2019 AT 6:07 PM

8 Replies

Tiny
SCGRANTURISMO
  • EXPERT
Hello,

This could be a number of things from the Ignition Control Module (ICM), The Power-train Control Module (PCM), The Spark Output (SPOUT) connector, spark plug wires, or the spark plugs themselves. But, in the diagrams down below I have included an Ignition System Troubleshooting flowchart for you to go through. Please go through it and get back to us with what you find out.

Thanks,
Alex
2CarPros
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Thursday, March 14th, 2019 AT 12:07 AM
Tiny
BIGJOHN610
  • MEMBER
I've performed all of those diagnostic tests. Once before I replaced the pickup coil, ICM, and coil with new Motorcraft parts. Then, I did them again last night after it shut off again. Still no signal to coil, spout or no spout. Today, a friend of mine let me borrow his distributor. Same result. Started and ran, then after about fifteen minutes, it shut off. No signal to coil. Put the distributor back on his truck and it started right up. I replaced the PCM a year ago with a rebuilt one. I'm leaning towards it.
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Thursday, March 14th, 2019 AT 2:46 PM
Tiny
SCGRANTURISMO
  • EXPERT
Hello again,

Okay, Can I get you to check the wire coming from the #1 cavity on the TFI Ignition Module Connector. Please run this wire back and check to make sure it has a good tight connection, and it is not damaged and there is no corrosion present anywhere. I have included a diagram of the connector and component locations in the diagrams below. Please get back to us with what you find out.

Thanks,
Alex
2CarPros
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Thursday, March 14th, 2019 AT 8:22 PM
Tiny
BIGJOHN610
  • MEMBER
Okay, I will.
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Thursday, March 14th, 2019 AT 8:26 PM
Tiny
KEN
  • ADMIN
Please let us know what you find. We are interested to see what it is.
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Monday, March 18th, 2019 AT 12:49 PM
Tiny
BIGJOHN610
  • MEMBER
As soon as I get in (I'm an otr truck driver) I'll check out the ground.
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Monday, March 18th, 2019 AT 8:03 PM
Tiny
BIGJOHN610
  • MEMBER
Ok. The ground is good all the way back to the ecm. I checked all the connections on all 6 wires and continuity tested. I checked the ignition suppression resistor, 21.9k ohms. All of this I did before starting the engine and after it died and went into a no start condition. Had a coil signal before it started. No coil signal after it died.
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Sunday, March 24th, 2019 AT 11:00 AM
Tiny
KEN
  • ADMIN
It sounds like the PCM went out, but to be sure let's check the wiring between the ECM and distributor. Here is a guide and the ignition system wiring diagrams. Also check the ECC relay.

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

and

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Check out the diagrams (below). Please let us know what happens.
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Monday, March 25th, 2019 AT 10:40 AM

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