I started my 93 Cadillac Deville and the heater came on full blast, haet
and blower (no defroster front or rear) and the electronic gas guage and
temperature contols both have a small letter c appearing in the wiondow.
The check engine soon light comes on after a few seconds. I can not access
the system for any codes, it appears non responsive. The car starts and
seems to run fine and all other controls other than the heater controls and
gas guage are functional. Any ideas?