Proheat X45–School Bus - Manual (Page 90)

5-33 SECTION 5. TROUBLESHOOTING & REPAIR
An HOUR METER (AUXILIARY OUTPUT) diagnostic code indicates an electrical
short in the hour meter (auxiliary output) wiring harness, electrical connections
or connected electrical load. The electrical load could be an hour meter, relay
or any other low load (< 1 A) connection that depends on the installation. This
error will not shut the heater down and heat to the engine will be maintained.
An open circuit will not display a diagnostic code.
Symptom: Hour Meter (Auxiliary Output) Electrical Load not Operating
(code indicated)
Check: Hour Meter (Auxiliary Output) Electrical Load
a) The wiring connections and polarity.
b) For an electrical short from the positive wire to the negative
wire. For an electrical short from the positive wire to the
chassis. Test electrical load. (See Test Procedure)
Hour Meter Troubleshooting (No code Indicated)
The following material covers the Hour Meter (Auxiliary Output) electrical problems
that do not indicate a Code 14. Note that the Hour Meter (Auxiliary Output) is
high side switched.
Symptom: Hour Meter (Auxiliary Output) Electrical Load not Operating (no
code indicated)
Check: Hour Meter (Auxiliary Output) Electrical Load
a) The wiring connections and polarity.
b) Test electrical load. (See Test Procedure)
Test Procedure:
a) Disconnect load/circuit to hour meter (auxiliary output) harness
and start heater. If error goes away, check for short circuits
in the load/circuit.
b) Restart the PROHEAT. If there is still an error, disconnect
the 18-pin internal harness and restart the PROHEAT again.
If code 14 is still present, replace PCM.
c) Check for correct voltage (12 V: 9 – 14 V, 24 V: 19– 30 V) at
the hour meter (auxiliary output) harness.
d) Reconnect hour meter (auxiliary output) harness. Start the
PROHEAT.
e) Connect electrical load directly to a remote power source of
the rated voltage (12/24 Volts). Does the electrical load run?
14 Hour
Meter
(Auxiliary
Output)
Figure 5-26 Hour Meter (Auxiliary Output) Test