I was driving my 89 Chevy C2500 truck and noticed it was about to hit 80,000 miles. Sometime after that I heard a loud crack sound, but did not know what it was. It happened when we were either going to or leaving a store.
Later on the way home I noticed that the odometer was stuck half way between 79,999.9 and 80,000.0 it did not move the rest of the drive home. After doing some research I determined that the odometer gear may have cracked.
The plastic in an 88 to 91 chevy truck is old and brittle, do not over tighten any of the screws when putting them back in. You will almost certainly find broken plastic on the gauge cluster bezel, and the screws that hold the headlight controls in place. A new bezel can be ordered from LMCTRUCK.COM
I took the dash panel apart. There are youtube videos on how to do this, it is very easy. I found that this gear (seen below with the red arrow) had a crack in it.
There are youtube videos to explain how to remove the gear, and replace it. Though I do not recommend heating the gear up. I ordered a 924-396 Odometer Drive Gear from amazon for a ridiculous $30.
However the gear has 2 extension from the hub, a large one and a small one. My original gear did not have the small one.
The small one indicated above with the red arrow had to be removed because I could not get the odometer back together with it there. I installed my gear by placing the gear over a vice spread just enough to allow the hub to go through. I placed the odometer in the hole, and carefully tapped it in place with a small brass hammer. Do not use a steel hammer. Be careful of how far you put the gear on, too far and you cannot join it back in place with the trip meter. Not far enough and you can't get the odometer back in place. Once the gear was on I estimated how far I had traveled (about 49 miles) after the gear broke, and advanced the odometer that much. The odometer cannot be moved backwards without taking it apart which would probably be a nightmare to put back together.
Once I had the odometer fixed I worked on my trip meter which had been broken at some point when my dad had the truck.
The above is a picture from an old ebay listing, and shows the back of the trip meter. The red arrow points at the piece of plastic that was broken. the trip meter cannot be reset if the shaft with the green gears is not in the correct place.
The above picture shows the 2 shafts from the side, the left one has a twisted wire on the top side of the shaft. I did the repair with the gauge panel still assembled as I did not want to take a chance of breaking it further by taking it apart to work on it. I wrapped a small piece of thin steel wire around the 2 shafts twice. The wires must go around the shafts as shown on the L side. with the 2 ends of the wire coming out of the top. I then carefully cinched the shafts tight enough so the trip meter reset would work. I twisted the wires together carefully, and snipped off all but about 3/16 of an inch of the twist. When completed the shafts were now correctly aligned, and the reset works. You must run the wire around twice, as you cannot cinch them together with only one loop of wire.
while setting the correct mileage I noticed that the odometer had a tendency to get stuck, and this might explain why it had broken when it had to move 6 disks. The odometer is driven by a motor, not a cable.
Because you have to turn the truck on and move the shifter all the way over to remove the control gauge cluster, when you disconnect the cluster that may cause a fault. This fault will show up when you get everything back together as the brake light will blink 8 times short and 1 time long then repeat. The error is an open circuit error in the brake controller. The error is false. I fixed mine by disconnecting the battery for 30 seconds.
some of the pictures in this post came from other sources as I was in too much of a hurry to take my own pictures.
