Speedometer does not work in my 52 M37

[dman]

I just had a new harness put in the truck (24V) and everything works great except the speedometer. What are the proceedures for trouble shooting? Should I just order a new gauage as the first step?

[Lifer]

The speedo is mechanical, not electric. Usually, any problem with it can be traced to the cable and/or its housing. I would suggest removing the cable to make sure it isn't broken or frayed. A broken cable, of course, means that the speedo won't work at all. A frayed cable will snag inside the housing and result in a clicking sound "somewhere under the dash" and an erratic reading. If either of these conditions exist, replace the cable.

It's possible that the cable is still serviceable but needs lubrication. All you have to do, then, is clean it thoroughly, wipe it dry, and apply a thin coating of white lithium grease along its entire length before reinstalling it.

If you are sure that the cable and its housing are good to go, you may want to consider having the speedo checked out and repairing or replacing it as necessary.

Happy hunting!

[ELBUFO]

I just finished re- rewiring my beastie. My speedometer didn't work from the get go. When I checked the connection , I found that the previous owner, after doing a chop job on the wiring, had not insured that the cable was seated in the speedometer when we was done. This caused the outermost part of the square hole that the cable slides into to become wallowed out. I used a square drive screwdriver bit to remove the burrs form the hole. Since a goodly amount was wallowed I removed the rubber gasket from the cable housing. This gave me about 1/8 to 3/16 more length on the drive cable. I used needle nosed pliers to pull the drive cable out as far as I could get it and insured that it was fully seated, before tightening the nut. It now works perfectly. How long will it last...Only the Gods know, but it was a cheap fix. Check it out...John