I have a 1999 ZR2 Blazer and I’m having a problem with my Trans shifting. So I bought this Blazer off of an old man that thought the trans didn’t work but it turns out the guy that he had install the trans never hooked the shift cable back up. So I hooked it up and it seemed to work fine. I ended up letting it sit for about a year and I came back to it this spring to work on it and I noticed my speedometer doesn’t work, doesn’t flicker or bounce, it’s just completely dead. Every other gauge works. I checked fuses and they’re all intact. And since the Blazer uses the speedometer to shift through the gears I’m currently stuck in 1st and when I drive the ABS light comes on a minute or so after driving (Turns off after I shut the blazer off and turn it back on the following day) I replaced the VSS on the transfer case and I replaced the Wheel speed sensors and still no luck. I’m narrowing it down to an electrical issue but from what I’ve gone over I hadn’t seen any frayed wires or worn out spots.

 

At what point in the circuit does the transmission get its speed information? Is it from the gauge cluster? I don't know why it would work, but could you get another gauge cluster to swap in to see it it helps? Perhaps the problem is with the speedometer gauge.