A few years ago I replace the 2 little plastic gears in the odometer, and got the odometer working again. Now, the odometer still works fine while the speedometer quit working. It went out intermittently for a few months until it finally won't work at all anymore. Again, the odometer still works fine. I cleaned the contacts on the connection on the transmission, but I was under the impression that they were ok already since the odometer hasn't stopped working. Any ideas? Thanks. -Jeff

 

Mine did the same thing, the speedometer worked for awhile after then just finally quit but if I hit a bump it would work again for awhile.

Pretty sure it is a loose connection on the speedo head, I need to pull the cluster and check them carefully.

Going to figure out a way to supply a pulse to the head to see it work out of the truck before I have it all back together.

I have been using my GPS for a speedometer.
Jim

 

Jim-

Thanks for the input. Let me know what you find. I figured I would have to take apart the dash again, just no more time right now.

-Jeff

 

That would be my guess also. Look for a cold solder joint, shows up as a dark ring in the puddle around a pin.

For a pulse, 555 is your friend.

 

In the 60's and 70's I have had many hours under a big magnifying glass and light chasing bad soldering joints.

I used to use a filament transformer capacitors and a voltage divider to calibrate analog tachometers against the 60hz.

 

Any update to this? I am having the same issue. My odo is dead on, but my speedo has been going out. Ive been using my GPS for speed, but I just moved to the UK and in order for my truck to pass MOT, I have to have a fully functional speedo....dont ask me why they wont allow the use of GPS