Gasboy Fuel Point Vehicle Module - Manual (Page 22)

Preparation for Programming Odometer Ratio (Enter ODO RATIO)
Page 4-8 MDE-4524A Vehicle Module Programming Manual· May 2006
Odometer Ratio (Enter ODO RATIO)
The VM receives odometer data as a series of pulses. These pulses may come from sensors
mounted to the transmission, transaxle, or drive shaft, or from circuits in the vehicle's
computer module or cruise control.
The vehicle's ABS system must not be used as a source for odometer pulses.
Any Fuel Point Vehicle Modules currently installed must be immediately
disconnected from the ABS system.
With electronic speed transducers, the connection should be made at one of
these locations: at the buffered output side of any vehicle's control modules,
such as the powertrain control module (PCM); or, if buffered output is not
available, at the transmission's speed generator signal wire.
IMPORTANT INFORMATION
The number of pulses-per-mile is affected by several factors, such as, tire size, axle ratio, and
transmission specifications. Due to all these variances, the VM requires you to program in a
ratio of the number of pulses it is expected to receive per mile. This section helps you to
determine the proper ratio for your particular vehicle. If you do not know the vehicle specs, the
VM Programmer has a calibration feature to help narrow down the correct odometer ratio.
Keep in mind that the ratio for the first counter field has a maximum limit of 640000 and the
maximum ratio for the second counter (for a dual VM) is 64000. For this reason, the first
counter field should be odometer and the second should be hours, when using a dual VM.
Mechanical Odometer Cable
Older vehicles use a mechanical cable to deliver odometer pulses to the dashboard. To allow
the VM to record these pulses, a mechanical transducer should have been purchased and
installed according to the guidelines and restrictions outlined in C35699 Fuel Point Vehicle
Module Installation Manual. The formula for figuring the mechanical odometer ratio is:
Cable revs/mile X sensor pulses/rev
Cable revs per mile is the number of revolutions the mechanical cable turns for each mile.
This number can be found in the transmission specification. Typically it is:
Domestic - 1000 revs/mile
Foreign - 900 revs/mile
Sensor pulses per rev is the number of electronic pulses generated for each revolution of the
sensor input. This is determined by the sensor manufacturer and may be stamped on the
sensor. A common value is 8 pulses/rev.