S-Prihadi

If code is current or fault still exist, DTC will never clear permanently.
DTC can become historic or STORED when and if the real fault is gone.

Left Coast Geek

ok, I got that orange cap popped out and unplugged the cable. ohm meter read continuity on the two pins of the squib (it read about 0.5 ohms but its not very accurate on low ohms). I didn't try and read bias voltage on the wiring side

S-Prihadi

I think the Bias voltage can not be read with a DMM, you need a scope.
It probably uses the small signal pulse like how ECM test its sensors. Low voltage and very low power and fast short signal, otherwise the pyrofuse will BLOW ... he he he.

Left Coast Geek

I do have an old fashion analog oscilloscope... haven't fired it up in about 10 years. its rated for 20Mhz ...

S-Prihadi

CRT version, sweet

Left Coast Geek

yeah, its probably late 70s/early 80s. its just a cheap BK Precision, 'student grade' as it were, not a proper Tek or HP. A friend was cleaning out his old shop and gave it to me about 10 years ago.