PROHEAT M-SERIES SERVICE MANUAL
2-4
NORMAL OPERATING
SEQUENCE
1.. . . . . . . . . . . . . . . Switch On:
6.
. . . . . . . . . . . . . . Cool Down:
5.
. . . . . . . . . . . . . . Full Output:
3. . . . . . . . . . . . . . . . . . Ignition:
2.
. . . . . . . . . . . . . . . Pre-check:
7.
. . . . . . . . . . . . . . . . . Standby:
8.
. . . . . . . . . . . . . . . Switch Off:
2.2
If the coolant temperature is below 160°F (71°C) the PROHEAT enters
Pre-check. If the coolant temperature is above 160°F (71°C) the PROHEAT
enters Standby.
The PCM performs self diagnosis checking sensors for correct range and
electrical components for over-load. Also during the first Pre-check, the Ignition
Module is powered for five seconds to allow a service technician to visually
check for a spark.
The Motor and Coolant Pump start first, followed by the ignition spark, and
Fuel Shut-off Valve. The Ignition Module sparks for 30 seconds during which
time the flame sensor must detect correct combustion.
At the end of the Ignition cycle the Flame Sensor checks the combustion. If
acceptable, the PROHEAT enters Full Output. If not acceptable, the PROHEAT
goes to Cool Down and then will start again at Pre-check. If the second start
cycle fails the PROHEAT will enter Fault Shut Down.
The PROHEAT will continue in Full Output until the coolant temperature
reaches 185°F (85°C) at the PROHEAT outlet Temperature Sensor.
The Motor and Coolant Pump continue to operate for up to three minutes, the
Motor stops and the PROHEAT enters Standby. The PROHEAT will Cool Down
for three reasons:
• Coolant reaches 185°F (85°C).
• A fault is detected. Go to Troubleshooting and Repair
• The PROHEAT is operating in Ignition or Full Output when it is switched off.
The Coolant Pump continues to circulate coolant throughout the system (go
to Auxiliary Input Section for alternative operating modes). When the coolant
temperature drops to its cycle on temperature, the PCM will repeat the cycle
starting at Pre-check.
If the PROHEAT is in Ignition or Full Output, it will Cool Down first, then shut OFF.
If the PROHEAT is in Standby, it will shut OFF immediately.
If the PROHEAT diagnostics sense a system or component fault, the PROHEAT will
shut down all components and flash a fault code(s) which best represents the
conditions. To reset the PROHEAT, it must be switched off and then on again.
NOTE: Damage may occur it the fault codes are ignored and the PROHEAT is
repeatedly switched off and on without addressing the problem.
4. . . . . . . . Combustion Check:
9. . . . . . . . . . Fault Shut Down:
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