Xerox Phaser 8400 Service Manual page 226

5.
Start up a terminal program, such as in window's HyperTerminal (usually located
in Programs:Accessories:Communications:HyperTerminal). Ensure the serial
port settings, usually COM1: is correct.
6.
Turn on the printer.
The trace should appear in the terminal dialog window. Examine the trace to
troubleshoot the problem. If necessary, save the trace file to capture the text.
4-86 Phaser 8400/8500/8550 Color Printer