You can read the error code from the "blinks" of the TPWS light. This will tell you what the TPWS thinks is wrong.
To do so:
1. Turn the iginition off
2. Connect the CG (pin 4) and TC (pin 13) pins together on the DLC3 connector (also known as the OBDII connector). You can do so with a small clip lead.
3. Turn the ignition on
4. TPWS light will light steady for three seconds
5. TPWS light will flash in a pattern indicating the stored DTCs (trouble codes). The pattern will require you to count the flashes and discern the delays between.
For example, if DTCs 13 and 23 are stored you will see:
0.5 second flash
1.5 seconds off (1)
0.5 second flash
0.5 second flash
0.5 second flash (3)
2.5 seconds off (gap between stored codes)
0.5 second flash
0.5 second flash (2)
1.5 seconds off
0.5 second flash
0.5 second flash
0.5 second flash (3)
4.5 seconds off (gap between repeating)
Then, it will start again and will repeat until you kill the iginition and remove the jumper.
What the codes mean:
11, 12, 13 or 14 (Tire pressure low on one of the 4 tires)
21, 22 ,23 or 24 (No signal from one of the 4 sensors)
41, 42, 43, or 44 (Transmitter ID error on one of the 4 sensors)
65, 66 ,67, or 68 (Abnormal temperature inside one of the 4 tires)
71 (Transmitter ID not registered)
73 (Vehicle speed or Engine Speed Signal Malfunction)
76 (Malfunction in TPWS ECU internal cuircuit)
91 (Vehicle Speed Sensor Error)
94 (Engine Speed Sensor Error)