Unplug the distributor and turn the key on and verify battery voltage to the distributor on the harness side on the Black/White wire, 5-volt references on the Green/Yellow and the Green/Black wires and ground on the Black wire.
Plug the distributor back in, backprobe and check voltages on all 4 wires one at a time while cranking. The Black/White wire should maintain good cranking voltage (like 10.5 to 11 volts). The Green/Yellow wire should read about 2.4 to 2.7 volts. The Green/Black wire should read about 0.2 to 0.6 volts. The Black ground wire should read 0.05 volts or less.
If the distributor voltages check good, then check voltages at the coil/power transistor assembly with the coil/power transistor connector plugged in and backprobing. The Black/White wire is battery voltage supply to the coil. The Black/Pink wire is the ground for the power transistor - look for 0.05 volts or less. The Blue wire is coil negative - verify battery voltage on the Blue wire key on and use a powered up 12-volt test light and check for a pulse (flashing test light) on coil negative while cranking. The White wire (or possibly solid Black) is the pulsed voltage signal from the computer to the power transistor - look for 0.1 volt or less key on and about 0.4 to 0.6 volts while cranking.
DistributorIgnition CoilIgnition Power TransistorWiring Harness The distributor inputs 0-5 volt square wave signals into the computer. Using a voltmeter instead of a scope, the voltmeter takes an average of the 0-5 volt square wave signals. When the computer likes the two distributor signals, the computer pulses a voltage signal out to the power transistor that is mounted with the ignition coil. This signal from the computer turns the power transistor on and off and the power transistor turns coil negative on and off.
THanks for the accept!
Let me know if you have any further questions!