2002 Cadillac Seville ABS & TC light comes on occasiona

Initially, what I would do is clear the codes, and drive until the warning indicator returns. See which codes(s) return. This will give a more definate indication of who is causing the fault. You will not need to return to dealer for diagnostics, your vehicle has an onboard feature that will display codes. To enter that onboard feature, push and hold the info up, and on/off button simultaneously, until the segments illuminate. You info center on the cluster should read ALL. From here you can use the info button to scroll modules alphabetically, up or down. Roll to ABS, and press on/off. It should change to ABS CODES, if you use the info button at this point it will toggle between that, and ABS CLEAR CODES? Like I said previously, clear them first, you can do this by pressing on/off. It will acknowledge by displaying ABS CODES CLEAR. Drive until warning indicators or message appears, and run this process again, only pressing on/off after the display reads ABS CODES. Report back.

That narrows it down to the right rear circuit. At this point, and the fact that it is intermittent, a few things are possible. The only situation may be when it is stationary, the fault does not occur. It is possible that you have a faulty rear wheel speed sensor(hub/bearing), terminals in the sensor connector(harness side) that have lost some tension/poor fitting, or wiring issues from the RR wheel sensor to the EBCM. There is one way of isolating the sensor, but it requires a bit of work. The right and left wheel hubs could be swapped(in contrast to just replacing the rh side). If you roadtested it afterward and your codes followed the sensor, then replace the hub. Looking at the terminals, it is not real obvious if they are lacking tension. Usually in the field, we use a male of the same type(in this case metri-pack 150 male), insert it into each female terminal, and if you invert it and the male falls out, it is loose. If you pick the rear wheels up off the ground, there should be no play when grasped at 12 and 6 and wobbled. I would proceed with either replacing or swapping the rear hub(your choice), if it doesn't change check the terminals, and if you still find nothing you are going to need to check wiring. That is where it may get a little complex.