Reset the Tire Pressure Monitoring Sensor on a Cadillac.

After rotating the tires the dash display no longer indicates when a tire is low. The owner's manual says the computer must be reset, but doesn't tell how.


Here’s how, straight from the shop manual:
Tire Pressure Monitoring Sensor Programming

    * Tool Required
    * J 41760 Tire Pressure Monitor (TPM) Programming Tool.

The Tire Pressure Monitor (TPM) system interfaces with the Instrument Panel Cluster (IPC) , Dash Integration Module (DIM) , and the Remoter Control Door Lock Receiver (RCDLR) via a class 2 serial data circuit to perform the sensor programming procedure. Once the program mode is accessed through the RCDLR, each sensor's unique identification code can be programmed into the RCDLR's memory. Each sensor must transmit it's ID code in the proper sequence in order for the TPM system to know the sensors location. A magnet must be held close to the sensor in order to force the sensor to transmit it's ID code. Once the RCDLR has received a sensors ID code a message is sent out on a class 2 serial data line to the DIM to sound a horn chirp, indicating that the sensor transmitted and the RCDLC received the ID code. If the programming sequence is cancelled before any sensor is programmed, the RCDLR will remember all current ID codes. As soon as the RCDLR learns the first sensor's ID code, all previously stored ID codes are erased from the RCDLR's memory. Loss of, or low vehicle battery voltage will cause the sensor ID codes to be erased from the RCDLR's memory. Before proceeding with the steps below, ensure the TPM option is enabled in the RCDLR and IPC.

Programming

   1. Turn ON the ignition, with the engine OFF. Important: If the sensor programming mode cannot be activated, ensure the TPM option is enabled in the RCDLR and the IPC as mentioned in the above supporting text.
   2. Press the key fob lock and unlock buttons simultaneously for several seconds. A horn chirp will sound indicating the sensor programming mode is activated. Important: If the horn chirp does not sound after 15 seconds, remove then replace the sensor programming tool over the valve stem.
   3. Starting with the left front tire, place the J 41760 over the left front valve stem, a horn chirp will sound indicating the sensor's ID code has been programmed.
   4. When the horn chirp sounds, proceed to program the next sensors in the following order:

          o Right front
          o Right rear
          o Left rear

   5. After the left rear sensor is programmed, the horn chirp will sound twice to indicate programming is complete.

Programming Cancellation
The programming mode will be cancelled if any of the following conditions are met:

    * The ignition is turned OFF.
    * All four sensors have been programmed.
    * The TPM system has been in the program mode for longer than 5 minutes and no sensors have been programmed.
    * If more then one minute has passed before the next sensor is programmed, all previously stored codes are erased from the receiver's memory.
    * Vehicle battery voltage is below 8 volts.
And that special tool isn’t that special—it’s just a big magnet. You can probably get one powerful enough at Radio Shack.