91 SC1

I have a 91 SC that has suddenly had the odometer stop working. All the
other gages, tach, and speedometer work just fine. I disassembled the
unit and cleaned and lubricated the odometer unit but it did not fix the
problem. It seemed that the odometer must be bad so I bought a used
complete head cluster at the local used parts store. The Odometer in
that unit does not work either. Now, on to the question... Does anyone
know why just the odometer would stop working and what can be done to
repair it? Is there a sensor somewhere that regulates the odometer?

Thanks

 

So the speedometer working? I believe that unit is purely
mechanical, so if the speedometer is working, the odometer should
too. Could be the used unit was already broken.

Certainly when you disassembled the unit you should have seen the
mechanism that connects speedometer to odometer, and anything that
could interfere with the connection.

 

Thanks for the reply. The entire unit is hooked up electronically.
There are no connections to the head cluster unit except wires. I traced
the circuit board to make sure there were no burn looking marks. I
guess the used unit was working since it had 144,000 miles on it.
Everything works in both the old unit and the other one I put in except
the odometer. Could it be there is some connection to the engine or
wheels (?) that has a sensor that could be the problem? Ideas on a
source to lookup the wiring? Thanks.

 

That still seems a little odd, as one would think that the
speedometer and odometer would be run off the same pickup on the
driveshaft. I wonder if there is some sort of interlock to allow
the unit to be used as a demo without registering miles, or some such?

I suppose you might poke around on the transmission to see if there
appear to be two separate speed pickups. Dunno where these would
be, exactly, though.

 

There will only be one speed sensor. The only reason I can imagine for the
odometer not working but the speedometer working, assuming a good
replacement instrument cluster (which may not be a valid assumption here),
would be some kind of strange power supply problem..

 

thanks, I was wondering that, too. Still, finding the diagram that
would show which wire controls the odometer is my next problem. I have
spent several hours looking on the net for one but have not had any luck
yet. Any ideas are greatly appreciated. I don't think I want to go to
the Saturn dealer to order a manual for the wiring diagram.