Not getting 12 volts to coil

Yes, I penetrated the insulation at the bulkhead for position # 16 for wire A1 10R and got 10.5 volts, but only 9 volts at the column connector (backprobe), wire J1 12 R.
Ok. If the seal you pierced is the one on the engine side of the firewaull, then it makes sense.
If you probed on the passenger compartment side of the firewall, then the resistance might be at the ammeter connections.

On the older A-body's and others that use the same firewall connector, backprobing the inside is fairly easy. On your car I don't know.

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