I also have a code 542 on a TSP 6000, but only after a Timeout or shutdown. If the battery is disconnected, the code does not show up, but if you leave the battery connected, let the unit go into timeout, and then try to use the unit it will throw a 542 almost every time. And yes, the ED1 contactor was changed, so was all the fuses involved. We don't have a know good Access 5 to change out. This only happens if the battery is not disconnected while shutdown, and the only way to get the code to go away is to disconnect the battery for awhile! the cable to the Traverse looks and tests good.
Any thoughts?

Look at your control cables for any breaks or shorts. The cable that runs with your traverse hoses at bottom of platform can cause this problem.