Trane Tracer MP581 Hardware Installation page 100

Chapter 15 Troubleshooting
Table 26. Universal input troubleshooting with a thermistor input
Step number
Step 1 Set the multi-meter to read dc voltage. Measure the voltage across the termi-
nals for the input you are troubleshooting. Verify the voltage you measured
falls into the gray area of the curve in Figure 53 for the current temperature.
If you do not see the voltage reading appropriate for the current temperature,
you have a sensor wiring problem.
If you do see the correct voltage for the current temperature, proceed to the
next step.
Step 2 Disconnect the sensor wires from the input terminals. Set the multi-meter to
read dc voltage. Measure the voltage across the terminals for the input you are
troubleshooting.
The voltage should be 4.75–5.25 Vdc (see Table 30 on page 92). If you do not
see a reading in that range, the Tracer MP581 has a circuit board problem.
Figure 53. Voltage measured across terminals vs. temperature
Temperature (
Figure Note:
The correct region is shown in gray. A range of measurements is shown due to the variability of reference voltages
and thermistors.
Table 27. Universal input troubleshooting with a binary input
Step number
Step 1 Disconnect the sensor wires from the input terminals. Set the meter to read dc
voltage. Measure the voltage across the terminals for the input you are trouble-
shooting.
The voltage should be 16.00–18.00 Vdc (see Table 30 on page 92). If you do not
see a reading in that range, the Tracer MP581 has a circuit board problem.
90
Action
o
F)
Action
Probable cause
Sensor wiring
problem
Circuit board
problem
o
Temperature ( C)
Probable cause
Circuit board
problem
CNT-SVN01C-EN