Electrical

Tiny
MICHAEL HAMILTON2
  • MEMBER
  • 1987 DODGE RAM
  • V8
  • RWD
  • AUTOMATIC
  • 120,000 MILES
Coil and plugs are not getting spark.
Sunday, May 15th, 2016 AT 11:39 AM

4 Replies

Tiny
CARADIODOC
  • MECHANIC
  • 33,873 POSTS
Do you have the Spark Control Computer or the four-terminal ignition module?
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Sunday, May 15th, 2016 AT 1:14 PM
Tiny
MICHAEL HAMILTON2
  • MEMBER
  • 1 POST
I have the ignition module.
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Sunday, May 15th, 2016 AT 4:04 PM
Tiny
CARADIODOC
  • MECHANIC
  • 33,873 POSTS
You will have a ballast resistor then too. Check for 12 volts on both sides of that. If you still have the dual resistor, check for voltage on all four terminals when the ignition switch is in the "run" position.

If the voltages are good, remove the coil wire from the center of the distributor cap and hold it close to a metal part of the engine and body. Watch to see if you get a single spark when a helper turns the ignition switch off. If you do, the module may be shorted.

You must also check the pickup coil in the distributor for continuity. You did not list which engine you have so I don't know if you have one or two pickup assemblies. Regardless, they are both checked the same way with an ohm meter. Typical resistance is around 500 to 900 ohms. The exact value is not important. What you are looking for is one that is open, meaning reading infinite resistance.
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Monday, May 16th, 2016 AT 6:37 PM
Tiny
CARADIODOC
  • MECHANIC
  • 33,873 POSTS
You'll have a ballast resistor then too. Check for 12 volts on both sides of that. If you still have the dual resistor, check for voltage on all four terminals when the ignition switch is in the "run" position.

If the voltages are good, remove the coil wire from the center of the distributor cap and hold it close to a metal part of the engine and body. Watch to see if you get a single spark when a helper turns the ignition switch off. If you do, the module may be shorted.

You must also check the pickup coil in the distributor for continuity. You didn't list which engine you have so I don't know if you have one or two pickup assemblies. Regardless, they're both checked the same way with an ohm meter. Typical resistance is around 500 to 900 ohms. The exact value isn't important. What you're looking for is one that's open, meaning reading infinite resistance.
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Monday, May 16th, 2016 AT 6:37 PM

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