88 chevy 1500 2 wd 700 R4 tranny.
Speedo occasionaly jumps around. I replaced vehicle speed sensor(vss)
this did not help. When speedo jumps around and you apply brakes it trips the ABS. This problem only happens occasionaly.

i would trace wiring and make sure you don't have something grounding out. you may have a bad gauge. I have never had this problem with mine, so i really don't know where to point you, sorry.

Just for the hell of it, have your alternator checked. I had a problem similar to this with a 1990 corsica, it was the alt causing it to jump.

i would trace wiring and make sure you don't have something grounding out. you may have a bad gauge. I have never had this problem with mine, so i really don't know where to point you, sorry.

Just for the hell of it, have your alternator checked. I had a problem similar to this with a 1990 corsica, it was the alt causing it to jump.


I just replaced alternator couple months ago. I will try to trace wiring soon. This truck has 254000 miles on it. Its still on orignal engine and tranny and going strong.