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Discussion Starter · #1 ·
Working on the above, car was running until someone tried to install a shift light. This was spliced in on the Blue Pulse Signal wire of the coil, as well as the coil power and ground wires. Car coughed a few times, then nothing. Tried different ECU, two different new coils, still nothing. Have square wave pulse going to coil on Blue and Red/Green wires, and they are 180 degrees out of phase as observed on a scope. Scope pulse appears to go from approximately 2v to 12v. Just for grins, put NOID light on injector and it is flashing as it should. Both Cam and Crank sensors are pulsing.

Now that the stage has been set, my question is the DC component of the Pulse Signal wires going to the coil; as noted above they show a low of about 2v so I measured with a Fluke 87 DVM and it's showing 1.88v on each signal wire. Should the Pulse Signal go to ground [0v] or is the 1.88v normal? My thinking is that this DC offset is preventing the ignitor circuit from collapsing the coil field, thus no spark.

Anyone have a thought on this or can someone measure the key on voltage of the signal wires on a similar 4 wire car?

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