I pulled this from another place that had a bit of details on it. I could be wrong but I swear my 97 Deville has the same issue

bulletin regarding this particular trouble code - TC0073. Its

bulleting 63-50-16 dated May 1996.

Basically, the bulletin indicates that there was a software bug

in the EBTCM (Electronic Brake / Traction Control Module) for

1996 Cadillacs manufactured with the last 6 digits of the VIN

number that are smaller numbers than as follows:

Concours / Deville --- 280478

Eldorado ------------- 614516

Seville -------------- 826978

If you are not having a "real" problem and are getting an

invalid DTC due to the software bug you should be able to

duplicate the problem as follows:

First, turn the rear air conditioning blower to the lowest fan

speed setting. Then, reset the TCS codes to that TC0073 is no

longer shown. Now, turn off your engine. Restart the engine

after a few minutes and then run the diagnostics again. You

should find that the TC0073 does not show up. You should be

able to drive around, turn the engine on and off, etc. and the

TC0073 should not appear provided that you leave the rear air

blower set to the lowest setting. After trying this out, turn

the rear air to the highest blower setting and then turn off the

engine. When you restart the car and run diagnostics the TC0073

should reappear again as though you have a problem. If this is

what happens and your VIN number is within the range as

indicated above then you are getting an invalid TC0073 message. 

You do not need to do anything about the message. You could

replace the EBTCM since the new ones no longer have the software

bug but that would probably cost you well over $600 and it just

isn't necessary.