PCM behaving strangely: compressor short, sticky fault, intermittent functioning

[beerobber]

I need some tips on how to diagnose potential PCM issues.

Our PCM operates intermittently. When we enable the robot, the compressor will give a little sputter, then the PCM will blink orange. The NI console reports a compressor short. But if we wiggle the wires, or ignore that issue and focus on other things, typically the compressor will kick in a few minutes later. It won't run smoothly, just 4-5 seconds at a time until it finally builds up to 120 on the high side. Might take 5-7 minutes to get there.

The solenoids won't fire reliably through the PCM. They work great manually, but during the times the compressor isn't running and the light blinks orange, they won't respond to code control.

We have replaced the compressor. We have replaced the PCM. We have run new power wiring from the compressor to the PCM. We've isolated the PCM on the CAN bus. None of these things made it reliable. The new PCM seemed to get itself into a working state a bit more frequently than the old one.

This is a tense moment for our team. Our first district event loads in Thursday night. We spent 4 of our 6 out-of-bag hours tonight, and we have 2 left. So with the robot in the bag, I can't take pictures and I can't try your suggestions until tomorrow night. But please load me up with ideas so we can get this issue cleared!

Here are some things I've read on other threads:
- Try moving PCM further from radio (not sure this will be possible, but we can try some shielding material to block RF temporarily for troubleshooting)
- Reapply firmware
- Use Weidmuller ferrules like http://www.ctr-electronics.com/cabli...le-16-awg.html
- Make sure CAN isn't running parallel to power

Thanks in advance for your suggestions.
--Chris