I have 04 4x4 with about 230K on it. About a week ago, my ABS/Slip light came on, now on every time I drive it. I checked sensors with OBDII and the are all reading wheel speed. I think I've narrowed it down to the module. Can someone tell me the work involved in doing this? Does this require a complete brake fluid change? Ebay has used ones for under 100.00. Thanks in advance for any input.