Bobthebuilder

Lent my 99 C280 sport edition to my son to drive since he didn't have a car. After about a year and a half, he finally got it back to me yesterday and the odometer reads 1F9176 instead of the mileage. The battery did go dead while he had it since it sat for a period of time after he got a car. The battery was so dead that the trunk wouldn't open to get to the battery. He ran a jumper under the hood to get power to operate the trunk - for some reason the mechanical key doesn't turn in the lock. He said he disconnected the neg first and reconnected it last. Had to code the radio as usual with a battery replacement, but all other dash functions work. AC and fan work. Windows work. Seats work. Reset the service interval indicator OK. Just the odometer gives me that funky reading.....1F9176 instead of the mileage. All the other dash lights and functions of the car seem to work except for the key fob which is old and doesn't seem to lock the car anymore (need to visit the dealer and pay my tithes for a new one). Any idea how to get the mileage to display again on the odometer? I had to disconnect the battery to clean the trunk due to the dirt he left behind. Was hoping that would reset things but still get that reading. As before, everything seems to work OK. Seats were always a little iffy, I can move them when the door is open but sitting in it with the door closed I need to turn the key. But the main problem is the odometer, need to see the mileage instead of the code that's displayed. Help would be appreciated.

khomer2

Have you tried removing and disconnecting the speedometer cluster as shown here?
This may reset the mileage reading.

Bobthebuilder

I'm out of town right now but I'll try that when I get back. I think I might have figured this out though. The F changes to an 8 intermittently so it could be the electronic digit display starting to go. I drove it a few miles and the digits are changing like it's tracking miles. Although this is pretty strange, the last oil changes my son did was at around 198K miles, now the odometer reads 189K miles. Somehow about 11K miles got dropped. A gauge repair guy told me when the eprom gets reset, it's usually a LOT of miles or the display looks like chinese characters. I'm hoping I can change out the ribbon behind the cluster to get a proper functioning display.