Jim Grant's Tech Tips
1500 4x4, ABS and Speedo Problems
Q: I own an ‘89 GMC 1500 4x4 and have two problems. First
is the speedometer, it works on and off. I wondered if you had any troubleshooting
tips as to where to look. Also, my brake light continually flashes - it
has brand new brakes and I tried disconnecting the battery but it continues.
I would appreciate some input.
is likely that the Anti-Lock Brake System is missing an input. That input
is the same input that makes the speedometer work. Have your technician
check the vehicle speed sensor (VSS). The VSS is located at the back of
the transmission and provides the information needed for the ABS and speedometer