How fail-safe cooling works
If the engine begins to overheat:
•The engine coolant temperature
gauge will move to the red (hot)
area.
•The message center will indicate
the engine is overheating.
•The
indicator will
illuminate.
If the engine reaches a preset over-temperature condition, the engine
will automatically switch to alternating cylinder operation. Each disabled
cylinder acts as an air pump and cools the engine.
When this occurs the vehicle will still operate. However:
•The engine power will be limited.
•The air conditioning system will be disabled.
Continued operation will increase the engine temperature and the engine
will completely shut down, causing steering and braking effort to
increase.
Once the engine temperature cools, the engine can be re-started. Take
your vehicle to a service facility as soon as possible to minimize engine
damage.
When fail-safe mode is activated
You have limited engine power when in the fail-safe mode, so drive the
vehicle with caution. The vehicle will not be able to maintain high-speed
operation and the engine will run rough. Remember that the engine is
capable of completely shutting down automatically to prevent engine
damage, therefore:
1. Pull off the road as soon as safely possible and turn off the engine.
2. Arrange for the vehicle to be taken to a service facility.
3. If this is not possible, wait a short period for the engine to cool.
4. Check the coolant level and replenish if low.
Never remove the coolant reservoir cap while the engine is
running or hot.
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3. The fuel cap may not have been securely tightened. SeeFuel filler
capin this chapter.
4. Driving through deep water - the electrical system may be wet.
These temporary malfunctions can be corrected by filling the fuel tank
with good quality fuel, properly tightening the fuel cap or letting the
electrical system dry out. After three driving cycles without these or any
other temporary malfunctions present, the
indicator should stay off
the next time the engine is started. A driving cycle consists of a cold
engine startup followed by mixed city/highway driving. No additional
vehicle service is required.
If the
indicator remains on, have your vehicle serviced at the first
available opportunity. Although some malfunctions detected by the
OBD-II may not have symptoms that are apparent, continued driving
with the
indicator on can result in increased emissions, lower fuel
economy, reduced engine and transmission smoothness, and lead to more
costly repairs.
Readiness for Inspection/Maintenance (I/M) testing
In some localities, it may be a legal requirement to pass an I/M test of
the on-board diagnostics system. If the
indicator is on, refer to the
description in the Warning lights and chimes section of the Instrument
Cluster chapter. Your vehicle may not pass the I/M test with the
indicator on.
If the vehicle’s powertrain system or its battery has just been serviced,
the on-board diagnostics system is reset to a “not ready for I/M test”
condition. To ready the on-board diagnostics system for I/M testing, a
minimum of 30 minutes of city and highway driving is necessary as
described below:
•First, at least 10 minutes of driving on an expressway or highway.
•Next, at least 20 minutes driving in stop-and-go, city-type traffic with
at least four idle periods.
Allow the vehicle to sit for at least eight hours without starting the
engine. Then, start the engine and complete the above driving cycle. The
engine must warm up to its normal operating temperature. Once started,
do not turn off the engine until the above driving cycle is complete.
2008 F-250/350/450/550(f23)
Owners Guide (post-2002-fmt)
USA(fus)
Maintenance and Specifications
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