1993 Check coil packs.

[corvette5001]

I recently pulled the ICM of my 93 and I was wondering if there is a check to check if its the coil pack(s) that are causing the problem or if its the actual module that is the problem. I heard about using an ohmmeter to check the packs but wasnt for sure on how to check them.

[maxwedge]

Cause what problem?

[sad-lumina-owner]

Originally Posted by corvette5001

I recently pulled the ICM of my 93 and I was wondering if there is a check to check if its the coil pack(s) that are causing the problem or if its the actual module that is the problem. I heard about using an ohmmeter to check the packs but wasnt for sure on how to check them.

Well the 'coil' is I think really a high voltage transformer.

A transformer is just a pair of coils, meant to boost the voltage of the original signal. In this case, a pulse is pumped through one coil, and the extra windings in the secondary coil multiply the voltage (but halve the current: nothing's free).

The 'bare' copper wire coils are actually insulated from each other by a thin plastic (dielectric) insulating coating (supposedly good for 50,000 volts!)

But the tightly wound coils can short when high voltages appear between close windings with large differences in voltage.

The basic things that go wrong with transformers/coils is two things;

(1) open circuit (wire break. This is rare, but bad connections are common, e.g. corrosion, wirebreakage, bad connector)

(2) short circuit (this is more common in high voltage transformers. For instance, older TVs and Computer monitors go darker or degrade in quality as the high voltage "flyback" transformer inside the TV starts shorting out. When a few windings short out, the high voltage isn't quite as high as before, changing the brightness or focus of the picture.)

To check your coils is easy, since you probably have more than one (my car has three dual coils to feed 6 cylinders).

No coil should be 'open circuit' from one end of a winding to the other.

All coils should have the same resistance (the many windings will give both a D.C. resistance and an A.C. impedance, and a good voltmeter can at least check for either open circuit or a short.)

All coils should be insulated (open circuit) between the primary and secondary coils. Check a wiring diagram (and pin-out), and make sure none of the coils are shorted between the primary and secondary either.

These tests can be done on a bench with all coils removed from engine.

[maxwedge]

Lot of typing, nicely done, but we still do not know what the root issue is!

[Manny_boy]

Not sure if you found what you were looking for, but this link may help you if you with coil pack/ICM testing:

http://members.fortunecity.com/slade...leshooting.htm