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kellcats521 kellcats521 is offline
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Join Date: Feb 2005
Location: Atlanta Metro
Posts: 219
The secondary coil has verrrrry low resistance.

I've seen 2 CDI boxes go bad that still made the noise, and I'd bet yours is bad.

You need to check the resistance of the green coax wire that goes from the pickup coil in the distributor to the CDI box - if you pull the 6-pin connector off of the CDI box (you should be able to reach in and get it w/o pulling the IC off even though it is pretty tight), you can pull the rubber boot back a bit and see the pins for the green coax wire, they are both on one end of the plug for pins 7 and 31D. Check the resistance across these 2 pins - it should be ~600 ohms. Then, switch your meter to AC volts and check these same 2 pins when someone cranks the motor over - you should see a low A/C voltage that WILL vary a lot (basically the pick up coil and magnetic trigger are sending a signal to the CDI box).

Then, with the ignition on, make sure the box is getting ~12V at pin 15, and that pin 31/1 is a good ground.

If all of this checks out, unplug the tachometer connections (pull out the tach and unplug it), and try to start your car - if it runs, the tach drive circuit in the CDI box is bad. If it still will not run, the CDI is bad. To verify that the CDI box is not producing any spark, you can measure the output voltage on pin A of the CDI harness (white wire at the coil) while everything is connected - you should see over 400v A/C at the white wire (also a changing voltage as each spark signal is sent, not a constant voltage).

Good luck,

Pat K
87 930
Old 08-21-2007, 10:31 AM
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