Jamar RAC Plus I, User Manual

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RAC Plus I User’s Manual
5-2
Frequently Asked Questions
Q. My RAC will not count. What’s wrong?
A.
In most cases, when a RAC Plus won’t count, it is not the unit itself that
has the problem. It is usually a problem with the interface sensor or wiring.
Check the following:
1. Ensure the RAC has a calibration number in memory.
The RAC
will not count if there is not a number in memory. As you switch on the
RAC, the calibration number will be displayed for about three seconds.
The factory uses .900 as the test number. If no number is listed, refer
to the Manual Calibration Procedure on page 3-7 for information on
how to enter a number.
2. Ensure that you are attached to the speed sensor output.
It 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.
3. Perform a Sensor Test
. Locate the Sensor Test button on the front
upper right of the Modular Distance Sensor. When pressed, this will
generate 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 RAC and press the CH 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 RAC should count when the
button is pushed. What number it counted doesn’t matter as long as it
did count.
If the RAC did count, everything from the MDS up to the RAC is okay
and the problem is most likely a poor connection at the vehicle’s speed
sensor. Make sure you have a good electrical connection at the tap in
point. Once you are sure you tapped into the correct location, it is always
better to wire solder the connection.
After checking the connection, plug the VSS Input connector back into
the MDS and try the RAC again.