as bluenose suggested do check the mast cable...
but...after looking in the service book the only mention of any sort of 3xx code is 300-399 and refers to traction control module-fault condition on page 6-38.
when you look at the troubleshooting for that it has several things to check.
1-recycle the key 5 times allowing a 10 second interval between cycles (proceedure to clear codes).
2-check the ground control station display and see if there is a code displaying there (if you havn't). It only suggest 2 codes there and it's either replace traction control module or go to next step 5.
3-confirm batteries voltage etc.
4-check battery voltage while charging.
5-check for short in harness between ground control station P5 to traction control module.

So maybe there are other things besides the mast cable that will cause this.
it's suggestions rule out the mast cable. (but check it anyway).