i got my rear gears changed on saturday . i went from the stock 2.73 to 3.42. anyway when the mechanic was done with the car i got in it and the first thing i noticed that both the abs inop and the brake lights were on. i aksed the mechanic about this and he told me that the problem was that since there are new gears there now the computer cannot properly read the sensor so it is causing the lights to turn on. is this possible? again i had no lights on b4 the install. can it possibly be a loose wire or something? thanks in advance for your help

 

He may not have plugged in the connector for the speed sensor on the rear end. No way to get more detailed without knowing some basic info about the car (why, oh, why do people never post this?).
What he told you is bunk.

 

well some basic info would be, the car is a 1998 z28 with an a4 no tcs .

 

I don't remember having an ABS light issue when I went from 3.42's to 4.10's years ago. Of course your speedomter will be off until you reprogram the PCM. Like Shoebox stated, double check that everything is plugged back in (ABS sensor in the top of the differential).

 

yeah what i did was i took off the wheel speed sensor on top of the diff and cleaned it really good put it back on and the light was still on. u think maybe the reluctor ring is on wrong or something?