Originally Posted by TerminatorX5

you need to read the codes... a faulty speed sensor can indeed cause plausibility error which will set tranny into faillsafe... somehow, the tranny is not always in the failsafe but the engine got the light on which stays on... this can point to a frayed wire... in absence of a diag software, if you are familiar with multimeters, you can try to measure the speed sensors... they are essentially diodes, resistance in one direction, no resistance in the other direction... you can measure the sensors right at the wheels, take one out at a time and measure it - time consuming, or you can measure all four of them right at the ABS connector - i would suggest this route, as you will find the culprit right away, then you can pull the specific wheel, to measure the actual sensor - sometimes, the sensor is good, but the wiring between the sensor and the ABS is not... it will save you a lot of money and aggravation... or, you can always can have the dealer feed you a line of BS at your expense...

good luck...