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H03011 - How do I adjust the Vehicle Speed Sensor pulse rate?
The signal pulses coming from the vehicle speed sensor are generated for use by the vehicle’s computer,
engine/transmission control, fuel management, ABS brakes, etc. The pulse rate can vary from 4,000 to in excess
of 100,000 pulses per mile. The Modular Distance Sensor (MDS) will condition and amplify these pulses for use
by the RAC. Since the higher pulse rates are not required for accurate distance measurements, the MDS
incorporates a divider circuit to reduce the pulse rate. This is done by adjusting the rotary switch on the front of
the MDS, as shown here.
H03011 - How do I adjust the Vehicle Speed Sensor pulse rate?
The signal pulses coming from the vehicle speed sensor are generated for use by the vehicle’s computer,
engine/transmission control, fuel management, ABS brakes, etc. The pulse rate can vary from 4,000 to in excess
of 100,000 pulses per mile. The Modular Distance Sensor (MDS) will condition and amplify these pulses for use
by the RAC. Since the higher pulse rates are not required for accurate distance measurements, the MDS
incorporates a divider circuit to reduce the pulse rate. This is done by adjusting the rotary switch on the front of
the MDS, as shown here.
Although your particular vehicle may vary, generally Chrysler and Ford vehicles use a 4 to 1 ratio (position 4 on
the switch) while General Motors vehicles use a 16 to 1 ratio (position 16 on the switch). To adjust the ratio, use
a small screwdriver to rotate the switch until the slot in the switch points to the desired ratio. Note that when the
switch is turned counter-clockwise until it stops, it is at the 1 to 1 ratio.
The adjustments go from 1 to 1 (1 pulse into the sensor, 1 pulse out) through 64 to 1 (64 pulses into the sensor,
1 pulse out). You may need to adjust the ratio again based on the results of the calibration procedure. Any time
you change the pulse ratio, you will need to re-calibrate the DMI.
the switch) while General Motors vehicles use a 16 to 1 ratio (position 16 on the switch). To adjust the ratio, use
a small screwdriver to rotate the switch until the slot in the switch points to the desired ratio. Note that when the
switch is turned counter-clockwise until it stops, it is at the 1 to 1 ratio.
The adjustments go from 1 to 1 (1 pulse into the sensor, 1 pulse out) through 64 to 1 (64 pulses into the sensor,
1 pulse out). You may need to adjust the ratio again based on the results of the calibration procedure. Any time
you change the pulse ratio, you will need to re-calibrate the DMI.