RAC Plus User’s Manual
2-2
Before You Begin
Note: The following instructions are for installing a RAC with a Modular
Distance Sensor. If you are installing a different type of sensor, refer to the
instructions that came with the sensor itself.
The JAMAR RAC Plus I and Plus II distance measuring instruments (DMI)
are very reliable instruments. However, there can be some external variables
that could affect proper operation and the ability to accurately measure
distance traveled. By observing a few simple precautions you will be able
to eliminate potential problems.
• Do not install wires near any object that could cause stray pulses to
be picked up, such as the alternator, spark plugs or engine coil.
• Do not install the wires or sensor near any objects that will get hot,
such as the manifold. The installation wires or sensor can melt if they
are too close to a heat source.
• Do not install wires near any objects that could vibrate and cut the
wires.
• Tire pressure should be the maximum suggested by the tire manu-
facturer, typically 32-35 PSI cold. The tire should have ample tread
depth. Steel belted radial tires are highly recommended.
• Drive the vehicle 3 to 5 miles (depending on climate) to warm the
tires up to normal operating temperatures prior to calibrating your RAC.
Refer to Chapter 3, Calibration for more detailed instructions.