Johno,
A communication error on the display indicates the dash display and main interface board (MIB) have lost communication. Check the #81, 82, 83 and 85 wires from the display to the MIB circuits for an open circuit. Also remove the J2 MIB connector and inspect the J2-3, J2-11, J2-15, and J2-18 pins in the plug for any pushed out pins or spread pins.
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