Proheat X45–School Bus - Manual (Page 76)

5-19 SECTION 5. TROUBLESHOOTING & REPAIR
Figure 5-17 Heater Voltage Measurement
Component Faults:
6 – Flame Sensor 9 – Compressor 12 – Blower
7 – Temp Sensor 10 – Ignition Coil 13 – Sleeper Fan
8 – Fuel Pump 11 – Coolant Pump 14 – Hour Meter
This section covers the individual heater components. In many cases
there is a corresponding indicator light on the PCM function display. The
indicator light only indicates an electrical problem, NOT a mechanical failure.
Component problems can also cause Function diagnostic codes.
A FLAME SENSOR diagnostic code indicates an electrical short circuit in the
flame sensor wiring or a flame sensor failure. In addition, it can also indicate
in rare cases the flame sensor detected a flame during pre-check (see Modes
of Operation Section). It will not indicate an open circuit. The flame sensor is
an optical device which “sees” the flame. If the sensor lens is dirty or has an
open circuit, it can not “see” the flame and results in either a START or a
FLAME OUT diagnostic code to display.
Check: Flame Sensor
a) Inspect the flame sensor wiring for a short circuit.
b) Inspect the flame sensor lens for cleanliness.
c) Test the flame sensor. (See following page for flowchart,
Figure 5-18.)
COMPONENT DIAGNOSTICS
6 Flame
Sensor
5.1.3
NOTICE
A SLEEPER FAN error (13) and HOUR
METER error (14) will not shut the
PROHEAT down and heat to the engine
will be maintained.