how do you clear the trouble code on a 93-94 cadillac sedan-de-ville 4.9 engine tks,
The first point is that there is a reason for the trouble code in the first place and clearing the code is just a temporary measure and it will appear. these codes do not set arbitrarily for no reason. 1993 and 1994 should be two completely different systems. 1993 is OBDI and 1994 is OBD II. The 1993 could be reset I believe through the heater control, but to be perfectly honest, I haven't had service manuals for the 1993 for at least 12 years, but you can go down to parts stores like Auto Zone and get a cheap code reader and an explanation of what the codes mean and how to reset the computer. On 1994 I used my OTC scanner to read and reset the codes. You can find these with manuals and software on Ebay these days with the case for $50 plus. The scannner plugs into the OBD II port at the bottom of the driver's side dash via cord.