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Primary and secondary coil test readings

Tiny
MS THUMPER
  • MEMBER
  • 1993 FORD ESCORT
  • 1.9L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 79,084 MILES
I am trying to test the primary and secondary coils. I do not have factory specs on what the coil readings should be. Can you offer some help with that? And the correct procedure for testing them?
Thursday, November 2nd, 2017 AT 7:54 AM

19 Replies

Tiny
PATENTED_REPAIR_PRO
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  • 1,853 POSTS
Here is that procedure:
1. Turn the ignition key "off".
2. Unplug the coil pack from the vehicle harness connector.
3. With the EDIS diagnostic cable negative battery lead connected, disengage the positive lead.
4. Measure the resistance between terminals VBAT + and C1 with a digital volt Ohmmeter (DVOM) set on the two kilohms scale. Refer to the accompanying illustration.
5. If the reading is not greater than 0.4 ohms, replace the coil.
6. Measure the resistance between terminals VBAT + and C2 with a DVOM set on the two kilohms scale. Refer to the accompanying illustration.
7. If the reading is not greater than 0.4 ohms, replace the coil.

Figure 2: Measure the resistance between the EDIS coil pack terminals VBAT + and C1 with a DVOM set on the two kilohms scale.
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Thursday, November 2nd, 2017 AT 8:33 AM
Tiny
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Fig. 1: Probe the terminals of the coil pack with a DVOM to check resistance.
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Thursday, November 2nd, 2017 AT 8:34 AM
Tiny
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That does not look right, let me try this.
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Thursday, November 2nd, 2017 AT 8:35 AM
Tiny
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Or maybe this.
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Thursday, November 2nd, 2017 AT 8:36 AM
Tiny
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That is better
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Thursday, November 2nd, 2017 AT 8:36 AM
Tiny
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Is it the same for the secondary coil as well? And would happen to know the specs for spark plug wires are?
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Thursday, November 2nd, 2017 AT 11:22 AM
Tiny
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What secondary coil are you referring to?
Spark plug wires are normally like 7,000 ohms per foot.
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Thursday, November 2nd, 2017 AT 1:12 PM
Tiny
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The ignition system secondary coil. These car has a electronic distributor-less ignition system (EDIS), but has a distributor and spark plug wires. Can you maybe explain what exactly this means? So would that make it a waste spark or what? The little bit of service information I have been able to find is very confusing.
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Friday, November 3rd, 2017 AT 10:23 AM
Tiny
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I think you mean the secondary ignition coil circuit, not necessarily a secondary ignition coil.
The secondary circuit is the high voltage side of the coil packs where the spark plug wires hook into.
Yes this does have a waste spark, "The ignition coil fires two spark plugs simultaneously, one on the compression stroke and one on the exhaust stroke."
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Friday, November 3rd, 2017 AT 1:07 PM
Tiny
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Ok, now its starting to make a little more sense. Thank you for your time. I managed to get the tests done. Thanks again.
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Tuesday, November 7th, 2017 AT 11:35 PM
Tiny
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Did the coil pass? Is the engine running? Why was you wanting to test the ignition in the first place?
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Wednesday, November 8th, 2017 AT 4:35 AM
Tiny
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A friend's car I've been trying to help them with. Yes the coil passed. It now has a dead battery. So about it running, still waiting to see.
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Wednesday, November 8th, 2017 AT 11:51 PM
Tiny
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Ok, thanks for letting me know.
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Thursday, November 9th, 2017 AT 4:23 AM
Tiny
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Thank you for your help.
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Sunday, November 12th, 2017 AT 6:55 AM
Tiny
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You are welcome.
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Sunday, November 12th, 2017 AT 7:19 AM
Tiny
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Do you know anything about 142f engines? Single cylinder, 4-stroke engine.
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Wednesday, November 15th, 2017 AT 12:18 AM
Tiny
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No, not really.
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Wednesday, November 15th, 2017 AT 4:42 AM
Tiny
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Ok, not a problem. Thanks again.
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Saturday, November 18th, 2017 AT 11:38 AM
Tiny
KHLOW2008
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Do you mean the engine used for portable pumps, etc?

Those are small cc engines.
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Monday, November 20th, 2017 AT 6:57 PM

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