How Can I Test Ignition Coil On GM Cars And Trucks 1988-1995″?
In the olden days, when the distributor was easily accessible, you could test the coil by pulling the coil wire, holding the tip near a ground, and having someone crank the engine. If the coil and coil wire were good, there would be an arc. It was also pretty easy to get a poke this way, but you could tell if you had spark. This was also a technique for testing individual plug wires. If you want something more elegant, and potentially less painful, get an ignition tester. Here is an example of one: http://www.surespark.com/ You can check the manual for your vehicle for the exact location of your coil. Sources: Cited – and a few owgodamits.
The coil is actually a step-up transformer with primary and secondary windings (coils). You can test it an ohm meter… in cap coils have test on side of cap under the cap (take off cap). Set to the 0-2M ohm scale and compare readings for the primary winding (across the plug studs) to the secondary winding (center conductor to one stud–that goes to the center of the distributor cap). If the resistance does not meet published specs for the coil then toss the coil. If you don’t have published specs for the coil then use these ranges as your general guide. Primary resistance: 0.2 to 1.4 ohms (ok) Secondary resistance: 3.6 k ohms to 11.8 k ohms (11,800 ohms) (ok) If there is infinite resistance on either coil there is a break in the coil… toss it. Another simple way to test is to pull a spark plug wire and attach a plug gapped to 0.020″ with the metal body of the plug grounded to the car and you should see a blue spark when the engine is fired.
