1998 Cadillac STS Traction Control

When does the activation occur, with or without a brake pedal input? If it happens with no brake pedal input, it is a traction event. If it happens with the brake pedal applied, it is an ABS event. If the lights are coming on, and a message is displayed, it has to be setting a code. You can check codes yourself and validate this. Press info button up, and on/off together until all segments light and then release (you can do this with key on, it need not be running). It will first display ALL, you can press on/off at that time to keep it simple. The first module that will display any codes is ABS, and that is what we are after. Record the codes, and reply to post.

The two ABS codes are all we are concerned with. The C1223 is LR wheel speed input is 0, and the C1227 is LR wheel speed excessive variation. Without a scan tool to read the specific wheel speed data, all I can do is suspect a faulty wheel speed sensor. It could be a module, or circuitry to that left wheel sensor as well. As far as at the home, the only way I can offer a means to narrow it down and confirm it is a sensor, is to swap the left and right wheel speed sensors and see if the code follows. This could prevent replacing unnecessary parts. If you were creative enough, you could also run some jumper wires from side to side, or change them in the EBCM module connector, but this may be more difficult. To swap the sensors, you would need to disassemble both brake assemblies and remove the hub/sensor from each side. Raise the left side rear and see if there is any play in the wheel that would indicate a faulty hub assembly.