Preheat/Postheat Cycle - Check - Dodge D250 1990 Service Manual

Electrical System
DODGE Turbo Diesel
Engine Electrical System Replacement Procedures
Page 8-23
Preheat/Postheat Cycle - Check
Prepare to time the Preheat cycle by watching the WAIT to
START light or using a voltmeter or testlight at the manifold
heater terminals. Turn the ignition key to the ON position, but
do not start the engine.
Note: The temperature in the intake manifold must be below
0°C [32°F] (for early electronic control modules before serial
number 0080000A) and 15°C [59°F] (for later electronic control
modules), for preheat to occur.
If the engine has not been running and the ambient
temperature is less than 15°C [59°F], the WAIT to START light
will come on and the heater solenoids should activate with an
audible CLICK.
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Check the voltage at both heater terminals. There should be
voltage at both terminals for the first 10 to 20 seconds of
Preheat. See the chart on a following page (Normal intake
heater operation) for the sequence of heater operation.
There should no voltage at the KSB valve during the Preheat
cycle, if the temperature Is less than 15°C [59°F].
If the engine has been running or the ambient temperature is
above 0°C [32°F] (for early electronic control modules before
serial number 0080000A) or 15°C [59°F] (for later electronic
control modules), the heater solenoids and Wait to Start light
will not come on. There is no Preheat cycle above these
temperatures.
15*C=
59°F
I N S
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