I've frequently had odd DTC's appear/disappear in the past & generally turn off any I don't need.

I've swapped PCM's recently and this one can run the fans at high speed, the previous only ran them at slow speed.

Now I'm getting these dtc's obviously the fans are kicking in full, noisey & cooling the car.

I've flashed with EEHack 4.7 & Kur4o's recent 4.92 and fans are coming on at 70C (car was still warm)

I've been getting
43d knock sensor which checks out OK with volt meter.
LT4 filter swapped back in, still has fault.

99 Tach output
Both are switched off. NO DTC's show up in EEHack.

I ran Gary Dougs Scan94-95 and that still shows the DTC 99 as active and won't clear.
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I dicked about with the tune zeroing the timer delay for fan tach output and got different DTC's... fan 1 dtc 77 & CCP/electrical fault (missed the no, EEHACK crashed)
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I don't suspect a mechanical or wiring issue as such.
PCM Knock sensor voltages checked out OK.

Alternator is 14.01
Body terminals on inner wing 13.8
PCM shows ecm input voltage as 13.1

I'll reflash with an earlier tune that doesn't show the fault.

I've also had 97 vss fault occasionally pop up.

Any thoughts?

TIA
Mitch