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H03003 - How do I calibrate my RAC-100/RAC-200?
In order to accurately measure distance, your RAC-100/200 must know the exact distance that the vehicle will travel based
on pulses from the vehicle's transmission.The calibration number is the automatic calculation that represents the number of
pulses received over a set distance. This number, once calculated, will remain accurate for any instrument requiring a
calibration factor until a change to the vehicle occurs, such as different size tires put on the vehicle, tire wear, air added to
the tires, etc. At that time, you must re-calibrate.
In order to calculate the calibration number for your particular vehicle, you must first establish a calibration course. The length of the course can be any
known distance more than 500 feet — 1000 feet is ideal. In general, a shorter more precise course is better than a longer imprecise course. Your
course should be straight and accurate, so take the time to measure the course using a 100' tape. Mark the beginning and ending points so they can
be seen from inside your vehicle. Remember, the course length can be any accurate distance over 500 feet, so for convenience you could use a
telephone pole or other marker as reference point.
Step 1
Slide the ON/OFF switch to ON. Your DMI will perform a brief Self Test. The current Calibration Number will be displayed for approximately three
seconds, then [C.H 0.000] will appear with the decimal between the C & H flashing.
Step 2
Align your vehicle to the marker at the beginning of the course using a reference point on or in the vehicle, such as a window post, door handle, your
shoulder, etc.
Step 3
Press the UNIT key to select feet. The FEET LED will come on and [ 0 ] will be displayed.
Step 4
Press the CAL key. [CL 0] will show up. The instrument is asking for the Course Length. Key in the length of your calibration course in feet using the
numeric keypad and press the ENTER key. [C.H 0] is again on the display. Press the C-HOLD key, C.H will go off.
Step 5
Drive the calibration course. The count you see represents the pulses seen from your transmission sensor and not the distance being traveled, so don't
panic when the display doesn't equal the actual length of your course.
Step 6
When you reach the end of the course, stop your vehicle so that you are exactly aligned with the end marker using the reference point on the vehicle
used at the beginning of the course Press the C-HOLD key and C.H along with the pulses counted will be on the display. Press the CAL key and CF
along with the computed calibration number will be displayed. Record this number for future reference. Press the ENTER key. Your calibration number is
now stored in the DMI's nonvolatile (permanent) memory and [C.H 0] is displayed. The calibration number will stay in memory for more than 40 years
until you re-calibrate or manually change the calibration number. You are able to view the current number every time you power on the DMI.
You should rerun the calibration course to verify the calibration for your vehicle. Press C-HOLD prior to measuring. If this is the first time you have
calibrated a DMI, you may want to run the course a couple of times to practice being properly aligned when starting and stopping at the course markers.
The calibration number used should be between .500 and 1.200. If your calibration number is below this range, you need to use a higher division factor
(such as 1 to 16 or 1 to 32) by adjusting the rotary switch on your MDS. Of course, if the calibration number is too high, use a lower division factor (such
as 1 to 1 or 1 to 2). Several calibration runs may be necessary to determine which division factor is best for your vehicle.
Refer to How do I adjust the Vehicle Speed Sensor Pulse Rate? for more information on this adjusting the rotary switch.
H03003 - How do I calibrate my RAC-100/RAC-200?
In order to accurately measure distance, your RAC-100/200 must know the exact distance that the vehicle will travel based
on pulses from the vehicle's transmission.The calibration number is the automatic calculation that represents the number of
pulses received over a set distance. This number, once calculated, will remain accurate for any instrument requiring a
calibration factor until a change to the vehicle occurs, such as different size tires put on the vehicle, tire wear, air added to
the tires, etc. At that time, you must re-calibrate.
In order to calculate the calibration number for your particular vehicle, you must first establish a calibration course. The length of the course can be any
known distance more than 500 feet — 1000 feet is ideal. In general, a shorter more precise course is better than a longer imprecise course. Your
course should be straight and accurate, so take the time to measure the course using a 100' tape. Mark the beginning and ending points so they can
be seen from inside your vehicle. Remember, the course length can be any accurate distance over 500 feet, so for convenience you could use a
telephone pole or other marker as reference point.
Step 1
Slide the ON/OFF switch to ON. Your DMI will perform a brief Self Test. The current Calibration Number will be displayed for approximately three
seconds, then [C.H 0.000] will appear with the decimal between the C & H flashing.
Step 2
Align your vehicle to the marker at the beginning of the course using a reference point on or in the vehicle, such as a window post, door handle, your
shoulder, etc.
Step 3
Press the UNIT key to select feet. The FEET LED will come on and [ 0 ] will be displayed.
Step 4
Press the CAL key. [CL 0] will show up. The instrument is asking for the Course Length. Key in the length of your calibration course in feet using the
numeric keypad and press the ENTER key. [C.H 0] is again on the display. Press the C-HOLD key, C.H will go off.
Step 5
Drive the calibration course. The count you see represents the pulses seen from your transmission sensor and not the distance being traveled, so don't
panic when the display doesn't equal the actual length of your course.
Step 6
When you reach the end of the course, stop your vehicle so that you are exactly aligned with the end marker using the reference point on the vehicle
used at the beginning of the course Press the C-HOLD key and C.H along with the pulses counted will be on the display. Press the CAL key and CF
along with the computed calibration number will be displayed. Record this number for future reference. Press the ENTER key. Your calibration number is
now stored in the DMI's nonvolatile (permanent) memory and [C.H 0] is displayed. The calibration number will stay in memory for more than 40 years
until you re-calibrate or manually change the calibration number. You are able to view the current number every time you power on the DMI.
You should rerun the calibration course to verify the calibration for your vehicle. Press C-HOLD prior to measuring. If this is the first time you have
calibrated a DMI, you may want to run the course a couple of times to practice being properly aligned when starting and stopping at the course markers.
The calibration number used should be between .500 and 1.200. If your calibration number is below this range, you need to use a higher division factor
(such as 1 to 16 or 1 to 32) by adjusting the rotary switch on your MDS. Of course, if the calibration number is too high, use a lower division factor (such
as 1 to 1 or 1 to 2). Several calibration runs may be necessary to determine which division factor is best for your vehicle.
Refer to How do I adjust the Vehicle Speed Sensor Pulse Rate? for more information on this adjusting the rotary switch.
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