the speedometer only works from 30mph and above.also the abs and brake lights are on.Just put a rebuildt tranny in and speed sensor is new

 

The RWSS (on the rear diff) is new? That (or the cable going to it) is the problem. Check the connection.

 

I have the same problem, is that caused by the rwss or the sensor on the output shaft on the back of the transmission.

 

that seems to be an endless debate. the one on the transmission/t-case is the vehicle speed sensor VSS. the one in the top of the rear diff is usually listed as the Rear wheel ABS sensor. either is available at local auto parts store for $15-20.

 

AAMCO scanned the computer and informed me that the computer indicates a speed sensor, and he showed it to me, which he pointed at the wrong sensor, he pointed and the neutral safety switch, i purchased the output shaft speed sensor, i think i am going to replace both rw/abs speed sensor and output shaft speed sensor to hope it takes cares care of my problem.

Thanks for your information

 

replace them one at a time to determine which is bad. keep any old parts that are still good as spares (for the next event). post your results back with all the keywords that will help the next person search....

 

Well I replaced the output shaft speed sensor and it did not take care of the problem, the speedometer jumped right up to 30mph, so i will replace the abs/speed sensor on the rear differential to see if that takes care of the problem, if not then back to the drawing board.

 

Ok i replaced the abs/speed sensor on the differential, having the same problem, speedometer starts off at 30mph, i guess the next thing is going to be is to check the wiring on the connections to see if it is a faulty wire or a bad connection somewhere.

Although my abs light shut off, one thing is fixed now, lol.

Does anyone have any additional thought, the tranny shop originally pointed out the Neutral Safety switch, can that cause the problem?

 

no. neutral safety/reverse simply allows the vehicle to be started in neutral/park and prevents it in R/D. it also turns on the backup lights in R. nothing to do with speedo.

 

chuy, what year is your truck ? if you have the later model with the digital odometer, there is a gauge test. hold in tripmeter while turning key to on. continue to hold the tripmeter in a few more seconds until odometer says CHEK, then release. all lights illuminate, and then gauges sweep to about 1/4, 1/2, then full. this may/may not help you.

i've also unsuccessfully battled speedo issues for 2 years, but mine is hot weather related. mine will ony fail in hot weather when sitting out in the sun and the dash gets good and hot. in normal weather its ok. if parked in the shade its ok. i've replace both sensors and the entire cluster, including speedo. no help. when mine is not working, its also dead during the gauge test, so i think mine is dash wiring or pcm wiring, or pcm itself.

see how yours reacts to the gauge test.