Speedometer Reading all over the place

Hi everyone. I just lost my speedometer completely. No readings on speed, mileage or trip. I changed the speed sensor and still nothing. I’m going to pull the sensor out again and make sure I put it in right. Can I spray Gunk brake cleaner on the nubs? 2003 pete 379 18 speed

 

Ye

Yes, spray cleaner is ok.
Did you check your Speedo gauge connection in the dash?

 

Not yet, been running hard. I’ll get a chamce this weekend to look everything over. Got a good used speedometer from a friend to test and will check the entire harness

 

It might be speed sensor or bad wiring harness going to speed sensor, either or both.

 

Well I changed the speedometer, which by the way, my original one was plugged in, and it didn’t work right away but then erratically started to work, them worked, but only got 8 miles out of it on a 50 mile trip. I guess I’ll pull the sensor out and clean everything as good as possible. If that doesn’t work, I’ll inspect, repair or replace the harness. Any other ideas would be helpful. Thanks everyone

 

And oh, by the way, I only had 900k+ on my original speedo and the one I borrowed has 700k. Nah that couldn’t be it. Don’t those things laat forever?

 

I had problems with my tach when I first bought my truck. Turned out to be the solder joints on the inside. I could wiggle the connector to get it working

To fix it I pried off the bezel and soldered it back together. It's lasted 5 years so far

 

So far NG. Does the sensor wire run directly to the speedometer or is it part of another harness? Would be great if it was separate. That would make it cheaper to replace. And easier.

 

Hi everyone. I found my problem. From the sensor there is a 16” wire that plugs into it. From there, there is a longer twisted double wire to the ECM. Right in the middle of those wires I found a chafed wire that had turned green from oxidation. Cut both wires and respliced and that solved the problem. Everything works as it should. For some reason that harness just kind of swings in the breeze. Few extra zip ties and good to go. Thanks to all for help and advice. Keep the shiny side up.