No power to the spark plugs on 1991 Ford E-350

When cranking the engine to start Im not getting anything from the coil to the distributor and therefore nothing to the plugs. I have replaced many parts (coil, ignition module)and am down to the brain. When I unplug brain and crank the engine ,I show power from the coil and when i plug it back in and crank again the power is gone. Is this a proper indication the brain is bad????

by in Williamson, NY on October 05, 2010
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1 answer 1 comment
ANSWER by , October 05, 2010
Do you have 12 volts at the red/green wire at the coil with the key on? If you don't then you need to check to check the power relay that feeds the coil. Check to see if you are getting a signal from the Ignition Module, because it is the Ignition Module that starts that first creates spark for the engine. You can check this by using a test light plugged onto the battery positive terminal, then use the test tip of the test light and touch the ground side of the coil ( tan wire ) while some one cranks the engine. The test light should REALLY blink on and off. If it does, and you have no spark, then you have a bad coil. If the Light does not blink, then you have either a bad Ignition Module or a bad Ignition Pick-up in the Distributor. Bottom line is that the Computer does not fire the coil on an EEC-IV system ( I was Ford Tech ).
COMMENT by , October 06, 2010
Dandid, can you tell me more about the power relay that feeds the coil? Where is it located? Still no spark. New p/u and distributer, new ignition mod. , new coil .