How to test ignition coil?
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Joined: Aug 2005
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How to test ignition coil?
I've got a 1970 bronco with 302 and the ignition is all stock. It will crank over but I'm not getting any spark off of the coil. I was wondering how to test the coil to see if its good. Do you check continuity or resistance with an ohmeter? The coil draws power from the igntion switch, right? The switch seems to be messed up, it won't go to the accessory position and doesn't spring back like it should. When you turn the key to on, it immediately cranks over. How much voltage goes to the coil from the switch with the key in the on position? Also, what leads on the coil do you check resistance?, is it baterry to where the plug wire comes out? Thanks for help.
Hotshot
Joined: May 2004
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From: The hills of No. Calif.
Here's a simple, unsophisticated test:
Remove the dist. cap and check to see if the points are closed. If not, turn the engine a little till they are. Pull the coil wire out of the dist. cap and set it to where it's got an air gap at the end to check spark. Then run a jumper wire from the pos. terminal of the battery to the Batt. terminal on the coil. Open and close the points repeatedly and see if the coil sparks with a strong blue spark at the end of the coil wire. If so, the coil is probably OK and you need to look at the ignition switch (since you're having problems with it) and the ballast resistor/resistance wire.
It won't hurt to run full voltage to the coil for a short time, that's what you're doing when you turn the key to the start position anyway since the solenoid bypasses the resistor for starting.
Remove the dist. cap and check to see if the points are closed. If not, turn the engine a little till they are. Pull the coil wire out of the dist. cap and set it to where it's got an air gap at the end to check spark. Then run a jumper wire from the pos. terminal of the battery to the Batt. terminal on the coil. Open and close the points repeatedly and see if the coil sparks with a strong blue spark at the end of the coil wire. If so, the coil is probably OK and you need to look at the ignition switch (since you're having problems with it) and the ballast resistor/resistance wire.
It won't hurt to run full voltage to the coil for a short time, that's what you're doing when you turn the key to the start position anyway since the solenoid bypasses the resistor for starting.
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