ABS, Brake and Tire Pressure Warning Lights

[Senna27]

I have a 2005 Matrix (automatic) that's 6 months old. I was on the highway (in the dry) a few days ago when three warning lights came on. Tire Pressure (flashing) ABS (solid) Parking Brake (solid). I pulled over and checked the tire pressures. They were all O.K. About 10 minutes later the lights went out. The next time I stopped I reset the tire pressure system.

The same thing happened again, 4 days later, on the highway, this time in the rain. 15 minutes later, they went out. The next day it happened again driving in the city. I took the car in and they said there is nothing wrong. No Codes/No Faults Found.

My work order had a comment "Customer to return if lights don't go out". At this rate I'll be dropping the car off every couple days!!!

What gives???

[Cyorke]

I know on my Sienna with tire pressure monitoring the ABS sensors are used to monitor air pressure. THis sounds sorta screwy but, they determine if one wheel is rotating slower or faster than the others and that is how the pressure monitoring works. So as the tire pressure in a tire drops that wheel will not rotate at the same speed as the others will and the ABS system will recognize it. Therefore setting the tire pressure light off.
I though Toyota had gone to all sensors in the wheel but if not maybe you have gotten some kind of debris on or around one fo the ABS sensors and it is causing all the lights to come on. Maybe you can get underneath it and see if there is anything athat may be causing the problem. Maybe could also be a faulty sensor. IT seems odd though that there would be no codes or faults when it happens. This is the only thing I can think of off the top of my head.

[ksbrace]

Generally, if the system gets input that doesn't makes sense, the ABS turns itself off and turns on the ABS light. This is so that the vast majority of failures at least leave you with "normal" non-ABS brakes. I'll second the guess that there might be gunk around an ABS sensor on one wheel or a bad sensor. When the computer gets a signal that says one wheel is going much slower than the others, the tire pressure is triggered. Because it is (supposedly) going SO much slower, the ABS engages to release the brakes to that wheel. When releasing the brakes doesn't seem to work, the ABS decides it is confused and shuts itself off. The parking brake light just means there is something wrong in the braking system somewhere (the ABS). From what you said, the fault must be brief, and after 15 minutes of everything looking OK the ABS system re-engages.

In the best case, the service people cleaned and tightened the sensors to inspect the system and it is fixed. This is my guess. If it happens again they will know they have to actually replace things.