1991 Cadillac DeVille Problems

One or more heater & AC (HVAC) air delivery and/or temperature mode door actuator may fail. This can result in incorrect air delivery or temperature. If this occurs, fault code(s) stored in the HVAC control module should be available to assist with diagnoses.

Problems with the anti-theft systems using the raised-chip key can prevent the car from starting. The wires in the steering column to the ignition lock cylinder tend to break. The the key and ignition lock cylinder must be replaced to correct this condition.

The electronic level ride system may not work properly; this may result in the rear of the vehicle riding too high or too low. Our technicians tell us that a height sensor or exhaust valve failure are common issues with this system. Proper diagnoses will be necessary to confirm the exact fault.

The spark plugs should be replaced every 30,000 miles and the spark plug boots should be checked for hot spots and cracks.

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.

Excessive carbon build up in the engine combustion chambers may be the cause of a smog check failure due to excess NOx emissions. A "top engine" decoarbonization cleaning procedure will commonly correct this concern.

The high-pressure power steering lines are known to leak.

The anti-lock brake system (ABS) control module may fail causing the ABS light to illuminate. Failed modules should be replaced to restore ABS operation.

The rubber section of an automatic transmission cooler line may develop a fluid leak . In some cases the leaking section of hose can be replaced. In others, the complete cooler line must be replaced to correct this concern.

It is common for the fuel level sensor in the fuel tank read the fuel level incorrectly. The sensor must be replaced to correct the condition. Our technicians recommend having the complete fuel pump module replaced on high mileage vehicles.

The trunk pull down switch may fail causing the trunk lid not to close completely. Our technicians tell us that the failed switch can be replaced without changing the complete pull down motor assembly.

This powertrain control module (PCM) may develop a fault with its electrical ground location at the front of the engine block near the starter motor.

The parking brake may not release automatically due to a failed vacuum switch or actuator. Our technicians tell us that if vacuum is supplied to the actuator when the transmission is in gear, the vacuum switch is functioning and replacing the actuator should correct this concern.

The air conditioning compressor may become noisy or develop a refrigeration leak, requiring replacement.

A coolant leak may develop from the water pump. The engine may overheat as a result of the coolant loss. A leaking water pump should be replaced.