Tech Articles

Odometer Fix

40 series trucks, particularly in the colder climates, have a tendency to develop an annoying problem with the odometer and speedometer. The former stops working - usually the 1/10 dial would turn but the kms wouldn't - and the latter would sometimes jump with the odometer tried to turn. Here's what I did to fix mine:

1. Remove the dash cluster, and the speedo from the cluster (you don't actually have to unbolt the other gauges if you remove all the screws).
   
   
2. Remove the speedo needle (pulls off) and face plate.
   
   
3. Just above and to the right of the odometer numbers is a small metal pin. Pull this out, and the odo can be removed from the plastic cage.
   
   
4. Remove the small e-clip at the left end of the odometer. (Of course mine went flying, but luckily I had one that worked, so be careful when removing it!)
   
   
5. Remove and stack all the number rings and the gear mechanisms between them.
   
   
6. Clean the metal rod thoroughly (mine was quite sticky, which is what I think caused the odo not to function properly). Also clean the inside of each number ring. Lube the rod.
   
   
7. Reassemble. I put my black number rings on in reverse order. Be careful that you get the numbers lined up evenly.
   
   

It was a bit surprising to find that I could easily have reset my odo to 0! I did an initial test on my by setting it to 204998 and using a robertson (squarehead) screwdriver bit in a drill to run it up to 205k. Worked fine. Now with almost 5k km real travel on it, it hasn't stuck at all.