OEM and Private Label Speedometers

Marshall Electric Programmable Speedometers
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Signal
Marshall speedometers work with signals from both hall effect and magnetic pickup (i.e. vehicle speed sensors) sensors. Any speed sender or electronic module that meets the following two conditions can be used with our speedometer:

1. Pulse range generated proportional to the vehicle speed
2. Output within the voltage ranges listed below:
   1. 3.0V peak (Square Wave) or greater, typical for 3 wire hall effect sender outputs
   2. 3.0V peak to peak (Sine Wave) or greater, typical for 2 wire vehicle speed sensor outputs

If you currently have a mechanical speedo (cable driven) you will need a GM or Ford hall effect sender.

Calibration (Pulses per Mile)
Pulses per mile (PPM) is the number of pulses that the speedometer receives for one (1) mile driven. The speedometer needs to know this information to accurately indicate speed. Marshall electronic programmable speedometers accept a very wide range of PPM (4,000 to 200,000 PPM). This is very convenient when making changes to differential gear ratios and tire sizes. Just recalibrate the speedometer whenever changes are made and the speedometer will automatically adjust for the changes and accurately indicate speed. Marshall speedometers come calibrated for 16,000 pulses per mile.

To calibrate:

1. With the ignition off, press and hold the CALIBRATION/TRIP button.
2. Turn the ignition on, then release the CALIBRATION/TRIP button.
3. The odometer/trip display will indicate CAL to verify that calibration mode has been accessed. The pointer will move to 50% scale.
4. Drive the vehicle EXACTLY one (1) measured mile then stop.
5. Press the CALIBRATION/TRIP button again to complete the calibration.
6. If the number of PPR is between 4,000 to 200,000 the odometer/trip display will indicate the actual pulses counted by the speedometer for five (5) seconds. This indicates a successful calibration.
7. If the number of PPR is below 4,000 at the end of one mile, the odometer/trip display will flash for five (5) seconds after the button is pressed. The calibration will not be updated, and the original calibration will be maintained. Correct the problem and recalibrate the speedometer.
8. If the number of PPR is above 200,000 at the end of one mile, the odometer/trip display will flash for five (5) seconds after the button is pressed. The calibration will not be updated, and the original calibration will be maintained. Correct the problem and recalibrate the speedometer.

Operation
Marshall speedometers have a digital odometer and 2 separate trip odometers (TRIP 1 & TRIP 2) that can be individually reset. Interfacing with the speedometer is done through the CALIBRATION/TRIP button.

1. The speedometer will always display the odometer at power-up.
2. Momentarily press the CALIBRATION/TRIP button once to display TRIP 1, which will be displayed until the speedometer is powered down or the CALIBRATION/TRIP button is pressed again.
3. Momentarily press the CALIBRATION/TRIP button a second time to display TRIP 2, which will be displayed until the speedometer is powered down or the CALIBRATION/TRIP button is pressed again.
4. Momentarily press the CALIBRATION/TRIP button a third time to return to the odometer display.
5. The speedometer will retain the TRIP 1 & TRIP 2 values even when powered down.
6. To clear TRIP 1 or TRIP 2, momentarily press the CALIBRATION/TRIP button until the desired TRIP is displayed, then press and hold the CALIBRATION/TRIP button for approximately 3 seconds until the TRIP resets to 0.

My speedometer does not respond at all, what do I do?
Check all of the wiring connections and power to the speedometer.
1. If the speedometer needle goes to zero when powered up, but does not respond when the vehicle is at speed, there is no signal to the green wire. Check to ensure that the green wire is hooked to the proper location for a valid signal. 2. If the speedometer needle does not go to zero when powered up, the speedometer is not grounded properly or does not have power to the (RED) wire. Check to ensure a good chassis ground. Verify that the (RED) wire has a 12VDC supply.

My speedometer does not read correctly, what do I do?
Recalibrate the speedometer. Be sure that you are driving exactly one (1) mile. The speedometer calibration accuracy is dependent upon driving exactly one (1) mile. Spinning the tires will skew calibration and the speedometer will not be accurate.