How fail-safe cooling works
If the engine begins to overheat:
•The engine coolant temperature
gauge will move to the red (hot)
area.
•The
andsymbol will
illuminate.
•TheService engine soon
indicator light 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.
REVIEW COPY
2005 U137 Excursion(hdw), Owners Guide (post-2002-fmt)(own2002),
Market:USA_English(fus)
Maintenance and Specifications
238
On board diagnostics (OBD-II)
Your vehicle is equipped with a computer that monitors the engine’s
emission control system. This system is commonly known as the On
Board Diagnostics System (OBD-II). This OBD-II system protects the
environment by ensuring that your vehicle continues to meet
government emission standards. The OBD-II system also assists the
service technician in properly servicing your vehicle. When theCheck
engine/Service engine soonlight illuminates, the OBD-II system has
detected a malfunction. Temporary malfunctions may cause yourCheck
engine/Service engine soonlight to illuminate. Examples are:
1. The vehicle has run out of fuel. (The engine may misfire or run
poorly.)
2. Poor fuel quality or water in the fuel.
3. The fuel cap may not have been securely tightened.
These temporary malfunctions can be corrected by filling the fuel tank
with good quality fuel and/or properly tightening the fuel cap. After three
driving cycles without these or any other temporary malfunctions
present, theCheck engine/Service engine soonlight should turn off. (A
driving cycle consists of a cold engine startup followed by mixed
city/highway driving.) No additional vehicle service is required.
If theCheck engine/Service engine soonlight remains on, have your
vehicle serviced at the first available opportunity.
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 yourCheck engine/Service engine
soonlight is on, refer to the description in theWarning lights and
chimessection of theInstrument Clusterchapter. Your vehicle may not
pass the I/M test with theCheck engine/Service engine soonlight 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.
REVIEW COPY
2005 U137 Excursion(hdw), Owners Guide (post-2002-fmt)(own2002),
Market:USA_English(fus)
Maintenance and Specifications
248
