Chart A-1, Won't Flash Code 12, No Mil: Notes

Malfunction Indicator Light (MIL) should remain on when ignition switch is in ON position and engine is not running. Battery voltage is applied to indicator bulb. ECM controls indicator bulb and turns it on by providing a ground path through Purple wire to ECM.

NOTE: Test numbers refer to test numbers on diagnostic chart.

ECM battery feed terminals B1 and C16 are protected by a fusible link in fuse/relay block, near battery.
If ECM terminals B1 and C16 have voltage, then either ECM grounds or ECM is faulty.
Using test light connected to 12 volts, probe each of the system ground circuits to ensure a good ground is present.