Jamar RAC-100, Manual

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RAC-100 and 200 User’s Manual
If Your DMI Fails to Calibrate
If your DMI fails to count during calibration, perform the following opera-
tional checks:
Step 1 Locate the Sensor Test button on
the front upper right of the
MDS, shown in Figure 3.1.
When pressed, this will gener-
ate an internal low-level signal
that is fed directly into the VSS
Input circuit. First, unplug the
VSS Input connector from the
right side of the MDS. Second, turn on the DMI and press the C-
HOLD key just like you would prior to starting a measurement.
Next, using a small pointed object (pen, pencil, screwdriver, etc.)
or your finger press the Sensor Test button for a few seconds. The
DMI should count when the button is pushed. What number it
counted doesn’t matter as long as it did count.
If the DMI did count, everything from the MDS up to the DMI is
okay and the problem is most likely either a poor connection at the
vehicle’s speed sensor or the connection is not at the correct loca-
tion to get the vehicle speed signal. The speed sensor output is
generally at the transmission or the rear differential. If you are
unsure about being attached to the correct output, disconnect the
plug and move the vehicle. If the speedometer does not function,
you have chosen the correct plug wires.
If you are at the correct location, make sure you have a good elec-
trical connection at the tap in point. Once you are sure you tapped
into the correct location, it is always better to wire solder the con-
nection.
After checking the connection, plug the VSS Input connector back
into the MDS and try the DMI again. If the DMI counts, you can
proceed with calibration. If the DMI still does not count, go to
Step 2.
3-4
Figure 3.1 – Sensor Test