71 PB
TROUBLESHOOTING
Diagnostic Code (Temperature Based)
Temperature Based:
Thermistors (sensors) modify VDC and is interpreted through the FMC.
Errors indicate a possible issue with the sensor, FMC, or the sensor has detected an abnormal condition (or an out of
parameter value).
Solution: Sensor error, FMC error, or abnormal condition.
VRP Sensor Bank contains 10 sensors for air and coil temperature. Each is 10k Ohm and must be unplugged from the FMC
to test against a resistance chart. The sensors have a two‑port molex connected to the FMC. They all share a common power
supply which can be checked against the other connectors for continuity and rule out the FMC.
Rule Out Thermistors:
A thermistor will only give an error code if the thermistor is shorted, 0 ohms, or opened, O/L. If the thermistor is out of
range, it may not give an error code and the system may not operate correctly.
Make sure your meter has a high enough range to read the sensor. If your meter only goes to 2k ohms and you’re trying to
read 10k ohms, it will read O/L.
Refer to Thermistor Values chart in Component Testing section
Rule out FMC - Continuity Check
The rst pin in each set can be
checked against the others to
make sure voltage has the ability
to ow through that thermistor
port.
Rule out FMC - Voltage Check
The Thermistor port can be
checked without the sensor
attached to verify proper voltage is
being passed through the molex.
Voltage should be ~3.3VDC
Figure 503
(Continuity check)
Figure 504
(Voltage check)
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