Location of speed sensors?

99 GMC Sierra 1500

Where would i find the speed sensor that is located in the tranny? Is it for sure in the tanny or is it in the transfer case? I know there are two in the front hubs that have recently been cleaned. I am still having problems with the abs and brake lights coming on during normal driving. these lights will stay on for the remainder of the drive until the truck is turned off. Also still have the problem with the abs kicking on during low speeds.

Your ABS speed sensor will be in the rear differential, also sensors will be mounted on each front wheel assembly. The transmission sensor is for the speedometer and the vehicle PCM.

If the light is on than there will be a code. Get it and then focus on that part of the ABS system! Overactive ABS can be a broken exciter ring or a speed sensor flakin out. Knowing which one is making the light come on will make finding the problem that much quicker and easier!

The ABS sensors are located in the rear differential housing and mounted to each front wheel's brake rotor backing plate. The vehicle speed sensor (VSS) is located on the tail housing extension of the tranny, driver's side, where the driveshaft is inserted. On 4wd trucks it is locted in the transfer case.

You don't mention on which axle(s) the ABS is malfunctioning...front or rear only? Both?