Service Manual

Engine Fuel Heater, Electric ISB, ISBe and QSB (Common Rail [...]
Page 5-6 Section 5 - Fuel System - Group 05
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Finishing Steps
Operate the engine and check for leaks or fault codes.
Engine Fuel Heater, Electric (005-008)
Initial Check
NOTE: The fuel heater is not controlled by the electronic
control module (ECM). A bimetallic strip acts as a
thermostat. The fuel heater will turn on below
approximately 4°C [39°F] and turn off above
approximately 27°C [81°F].
Remove the 2-pin connector from the fuel heater.
Check for proper voltage to the fuel heater thermostat
control.
Fuel Heater Voltage
12-volt system - 12 VDC
24-volt system - 24 VDC
If the voltage is not within specifications, refer to the OEM
troubleshooting and repair manual.
Check the wiring between the thermostat control and the
fuel heater
Check voltage at the OEM harness connectors.
NOTE: Voltage out of the thermostat will be zero if the
temperature is above the range needed to turn on the
thermostat.
NOTE: The fuel heater on engines without EGR is
controlled by the electronic control module (ECM). The
CM800 ECM contains a relay that turns the fuel heater on
and off based on the fuel temperature sensor reading.