Tire pressure monitors

I have a 2002 Grand Caravan ES with tire pressure monitors from the factory. Recently had the tires rotated during service. After leaving, the overhead console started reading "1 tire High Pressure". I have double checked the tire pressures and all are consistant. Took it back to the garage and they retrained them. OK when I left, once again message came up after turning the car off.

Owners manual says to retrain after tire rotation.

Today I went to the dealer and bought the retraining magnet. I went through the retraining sequence and it said training complete. Took it out for a drive for about 10 miles. Message never came back on. When I got home I turned it off and then back on, message is back.

Does some error code in the computer need flushed???

Van has 96,0000 miles and has never had this problem before, just since last tire rotation.

I have read on this site that pulling the IOD fuse can help many electrical problems, so I tried that. Still comes up with the warning.

I tried lowering the pressure in the tires to 20 pounds. Now it reads "3 tires Low Pressure". It appears that one sensor is reading wrong.

Does anybody understand the computer that controls these?

Any suggestions?????

I can monitor the old fashioned way but the console readout is annoying and comes up and overrides other information.

Try moving the tire that was on the problematic sensor back to that point and see what happens. It is possible that the sensor is damaged and needs to be replaced. Also check suspension components to make sure the angle is correct. These sensors often work based on the angle of the wheel hub to the rest of the suspension, a low tire would cause the light to come on like it did when you lowered the pressure. If there is a suspension issue it may be causing the entire problem. Just a couple of things to look at.

Took it back to the original shop today. They re-rotated the tires back to their original positions. I am running directional tires, so it was pretty easy to guess which position they came from. He then retrained again.
Went to pick it up and service manager said it was fixed. He drove it for about 20 minutes and the message did not come up. I asked if he had turned it back on after shutting off. No he hadn't. When I started it in front of him, message came back on.
He recommends I replace the sensor--it must be bad. Seems ironic that it functioned perfectly for 96,00 miles and then wnet bad the very afternoon he rotated the tires.
Can these be damaged in any way??? Or is there something we are overlooking??

I have discovered that the monitor is fine at lower temperatures while driving at night. I realize that pressure builds up as the tires heat up, but below 75 degrees I can drive unlimited distance without the monitor going off. As soon as the temperature goes over that, even parked, the sensor activates.

I have also discovered that the tire dealer also utilizes nitrogen for filling tires. Can this plug the sensor hole or change how the monitor works?

No, nitrogen doesn't expand or contract like air does so that may be why the sensor isn't working correctly but it will not damage the sensors.

I think I have finally eliminated the problem.
After fooling with trying to figure out which one was setting the alarm off, I let all the air out of all the tires and pumped back up with a garage air compressor. Problem has gone away now. Have put neaearly 5,000 miles on since and no constant alarms. Had it go off once and added a little air to one of the tires and problem went away.
My theory was that the monitors do not like to work with nitrogen and as soon as I replaced it with "normal" compressed air. problem is gone.