95 ZJ Limited 4.0L odometer
 

A few months ago I purchased a used 1995 ZJ Limited (4.0L) with approx. ~227,500 miles

I noticed a few days ago the odometer reading is approx. ~218,900 miles

I'm trying to figure if something wrong with the odometer? Have others had a similar problem? It currently seems to be working only it has lost a few miles.

It's appears to be a hybrid mechanical / electrical odometer that doesn't use a speedometer cable.

Information from a 95 ZJ's FSM

All gauges except the odometer are air core magnetic units.

SPEEDOMETER/ODOMETER

The speedometer/odometer gives an indication of vehicle speed and travel distance. The speedometer receives a vehicle speed pulse signal from the Vehicle Speed Sensor (VSS). An electronic integrated circuit contained within the speedometer reads and analyzes the pulse signal. It then adjusts the ground path resistance of one electromagnet in the gauge to control needle movement. It also sends signals to an electric stepper motor to control movement of the odometer number rolls. Frequency values for the pulse signal are shown in a chart in Specifications.

Frequency

44.4 HZ ----- 20 mph -1.5 - +4.5
88.8 HZ ----- 40 mph -1 - +4
122.2. HZ --- 55 mph -.3 - +3.3

The VSS is mounted to an adapter near the transmission or transfer case output shaft. The sensor is driven through the adapter by a speedometer pinion gear. The adapter and pinion vary with transmission transfer case, axle ratio and tire size. Refer to Group 21 - Transmission and Transfer Case for more information.


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