Incorrect Speed Reading (Speedo OK)
 

Hi all,
I was driving home at night, and blew the fuse to my dash lights, so looked to use the speed/rpm readings on the PFC commander. At first, they seemed normal, but I stopped and restarted the car, and after that the speed reading on the PFC was totally haywire... jumping around from 105kph to 120kph in a matter of seconds, sometimes even wild swings to the 200kph range.

I used the flashlight on my phone to see the dash, and there was no such disturbance on the actual speedo. I'm wondering how this could happen, or if anyone's seen it, or if it could affect anything else. RPM was fine, though read slightly higher (1-200 rpm) on the PFC.

Insights appreciated.

Having the same issue with mine.... Any fixes?

Nothing yet... yours is the first response.

FWIW I had a similar issue and it was the speedometer. The PFC gets its speed input from the speedometer so a bad capacitor or diode could be causing problems. On my car the PFC speed reading went bad first, and eventually the speedometer started to intermittently bounce or just stay at 0 mph.The PFC speed behaved just like you describe even when the speedo was working normally. I fixed the issue by sending my gauge cluster to Hamps Speedometer Repair in Georgia.

Well, the odometer diode recently went bad (no readout), so that's probably it. Thank you.