CAN-Bus not communicating with anything

[mrian]

On my 2003 base model, I have a lot of electrical gremlins I've been tracking down since I bought the car. I finally bought a Foxwell OBD reader, and I got a plethora of codes. They include "CAN-Timeout, Instrument Cluster-No signal (DME, ABS, PCM, Air Conditioning, Fuel Level, Oil Level, Airbag), and what I believe the problem is actually, Instrument Cluster (No Signal B+, and Implausible Signal Power Supply)". I will list the code numbers at the bottom of this post for anyone who is interested. The Porsche troubleshooting manual recommends replacing the instrument cluster for most of the no signal faults, but for the last 2 that I have a hunch about, it suspects wiring, and I also suspect an open in the CAN-wires. I have no problem checking wires with a multi-meter, but I don't have a good bearing with where these wires might be located in the vehicle, weather this might be a CAN-hi or CAN-lo problem, and what some likely spots my issue might be at (ie grommets through the firewall, etc). Additionally, to my knowledge the 2003 model year is the first model year to have a CAN-Bus, which has made my search for information difficult (shoutout to charm.li for having manuals). I may be on the wrong track entirely, but I would really appreciate any insight into this problem!
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Code list; P1601, P0071, P1576, (Instrument Cluster) 36, 9110, 9111, 9114, 9115, 9122, 9123, 9130, 9131, 9140