Preheat Mode - Proheat M50 G-II PCM Service Manual

6. Standby
7. Switch "OFF"
OFF
8. Fault Shut
RED
INDICATOR
LIGHT
1. Momentary
GREEN
Switch "ON"

Preheat Mode

2. Pre-check
3. Ignition
4. Full Output
PROHEAT M-SERIES G-II PCM SERVICE MANUAL
Always ensure that the PROHEAT is allowed to Cool Down (Purge) for a full 3
minutes. If the power is shut off without a proper Cool Down (Purge) during
Full Output, DAMAGE TO THE HEATER MAY OCCUR.
The Coolant Pump continues to circulate coolant throughout the system.
When the coolant temperature drops below 160°F (71°C), the G-II PCM will
enter the cycle starting at Pre-check. The PROHEAT will continue to repeat
Steps 2 to 6 until it is switched "OFF."
The ON/OFF switch lamp, timer lamp or OEM indicator (installation options)
will turn off. In addition, the G-II PCM Indicator Light will turn OFF.
If the PROHEAT is in Full Output, it will Cool Down (Purge) first and 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
Down
will shut down all components and flash diagnostic code(s) which best
represent the conditions. The flash codes will be shown on the G-II PCM
Indicator Light in RED. In addition, the ON/OFF switch lamp, timer lamp or
OEM indicator (installation options) will also flash the same code(s). To reset
the PROHEAT, it must be switched off and then on again.
NOTE: Damage may occur it the diagnostic codes are ignored and the PROHEAT
is repeatedly switched off and on without addressing the problem.
2.3.2 PREHEAT MODE (ENGINE OFF)
NOTE: Only the G-II PCM has an indicator light. See page C-1 for more information.
The ON/OFF switch lamp, timer lamp or OEM indicator (installation options) will
light. In addition, the G-II PCM Indicator Light with turn ON GREEN. If the coolant
temperature is below 150°F (65°C) the PROHEAT enters Pre-check. If the
Signal
coolant temperature is above 150°F (65°C) the PROHEAT enters Standby.
The G-II PCM performs self diagnosis checking sensors for correct range,
electrical components for over-load and for a flame presence. Also during the
first Pre-check, the Ignition Module sparks for five seconds to allow a service
technician to visually check for a spark. If there are no errors indicated, the
PROHEAT goes to Ignition.
The Motor and Coolant Pump start first, followed by the ignition spark, and
then Fuel Solenoid Valve opens. The Ignition Module sparks for 30 seconds
during which time the flame sensor must detect a correct flame.
• If the PROHEAT detects proper flame at any time during the 30 second
ignition cycle, the PROHEAT enters Full Output.
• If the PROHEAT does not detect proper flame during the 30 second ignition
cycle, the PROHEAT enters Cool Down (Purge). The PROHEAT will attempt
to start again moving into Pre-check after Cool Down (Purge). 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'S Dual Mode Temperature Sensor. The PROHEAT
closes the Fuel Solenoid Valve and goes into Cool Down (Purge).
CAUTION
2-7