No spark and i can only get 5V at the coil.

YoungDart75 said

I just put a brand new ignition switch in the car last week, wired up exactly the same as the last one. The blue wire from the ignition switch shows 10.9V coming out of the ignition switch at the connector under the dash by the steering column , firewall connector and at the ballast. The brown wire shows 5.6V at the connector under the dash by the steering column, firewall connector and at the ballast as well.

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With the key in the RUN position, the brown wire will show the coil+ voltage back up through the firewall and to the ignition switch; this is because that brown wire is not connected to anything by the ignition switch in RUN and the coil - voltage backfeeds back to the switch terminal.

But your reading of only 8.7 volts on the brown wire and at the coil + is a possible sign of an issue. It should be close to battery voltage which will drop some when cranking but normally not that much.

1. Turn the key to START and record voltages at battery +, and the 12v input to the ignition switch (should be a red wire) to see how much the battery voltage and the wiring from the battery to the ignition switch are dropping.

2. Please do the test that I asked a couple of days ago so we can move forward some and start sorting out what is good and bad. Place the spark wire from the coil 1/4" from metal and remove the wire from coil -, then put the key in RUN, and then use a jumper or screwdriver to ground and unground coil - . See if you get a spark each time you do this. Don't be holding the jumper or screwdriver blade when you do this or you will get zapped. This will tell us more of what is good or bad in the system.

3. Test the coil resistance please. Do this with the coil - wire disconnected.

BTW, the irregular arcing is not normal and is the symptom of not running.