I have a 1994 GMC Sierra 5.7L K1500 and am having an issue with the speedometer. For awhile the speedometer was cutting out completely and drop to 0. Recently, it has started to “jump” around. It will sit around 10 mph lower than my actual speed and then bounce up and down within 10mph of what I’m actually doing. Any suggestions on what I can do to narrow down the malfunctioning part?
Brian in Boise, ID
Gm trucks have had this issue for many years. I had my 2004 GMC instrument cluster completely changed out(free) because of the same problem you have. Repair can be quit expensive.
Hope you get a break from GM.