1990 Cadillac Seville STS Repair and Maintenance
A guide to problems, costs, maintenance and repair for your 1990 Cadillac Seville STS
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1990 Cadillac Seville STS ProblemsInspect transmission/fluid every 30,000 miles
You may be able to prevent transmission problems by servicing the transmission and inspecting the fluid every 30,000 miles. If the fluid is dark or burned then the transmission system should be completely flushed.
The spark plugs should be replaced every 30,000 miles and the spark plug boots should be checked for hot spots and cracks.
One or more heater & AC (HVAC) temperature and/or air delivery mode door actuator may fail, resulting in improper temperature or air delivery. If this occurs, fault code(s) should be stored in the HVAC control module which should assist in diagnoses.