Rack Control Module
TM
Product Manual
Rev. 1.2, May 9, 2014 Page 31
4 Troubleshooting
The following troubleshooting instructions are specific to the RCM only. Refer to the
TD80 Installation and Operation Manual, TPM 001 for full TD80 Level Gauging and
Overfill Prevention System details. The RCM may be installed in any currently
recommended TD80 system including one that performs onboard loading control. These
details are beyond the scope of RCM installation and testing.
It is strongly recommended to complete the installation tests at step 16 once any failed
component(s) have been repaired or replaced. A UTT is required to thoroughly test the
entire system and provides the confidence in having a correctly and safely operating level
gauging and overfill prevention system.
Equipment Required: The following items are the minimum equipment required
depending on the nature of the failure.
1. Automotive Test light, 6VDC to 24VDC
2. Short length of wire bare at both ends or with alligator clips.
Optional Equipment: May be required depending on the nature of the failure.
1. Digital Multimeter (DMM)
2. Universal Truck Tester (UTT) for 5-wire optic and 2-wire thermistor installations.
Overview and General Techniques 4.1
The test light is a multi-purpose tool for checking the presence of power or ground in an
automotive electrical circuit. The tip is usually pointed and sharp enough to pierce the
insulation of a wire for circuit testing. Most test lights have a low resistance path due to
the cold resistance of the light bulb. This makes it useful to apply either power or ground
to a part of the circuit. Short circuit current is limited by the light bulb to several hundred
milliamps in a typical automotive circuit. Care must be taken because even this low
current may damage some low power electronic devices. The value of a test light is its
inexpensiveness, ruggedness, ease of use and indications are readily apparent at a
glance.
1. Check presence of battery power
1. Test light clip is connected to power common or ground/return to battery power.
This is usually the chassis of the vehicle.
2. Probe with test light tip in all circuit points that are energized by battery power.
a. Dim or dark light indicates low or no voltage due to a high resistance
connection or open circuit.
2. Check presence of circuit ground or power return
1. Test light clip is connected to battery power.
2. Probe with test light tip in all circuit points that are connected to circuit ground.
a. Dim or dark light indicates a high resistance connection or open circuit.
Varying brightness of the light bulb indicates an intermittent connection. This could be
from any combination of faults listed below:
1. Corroded connector pin/socket, terminal or crimp
2. Loose screw on terminal
3. Corroded wire or splice
4. Pinched wire shorting to power, ground or another signal
5. Poor solder joint
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