Ford 1999 Crown Victoria Owner's Manual page 157

What you should know about fail-safe cooling
If the engine coolant supply is depleted, this feature allows the vehicle to
be driven temporarily before incremental component damage is incurred.
The "fail-safe" distance depends on ambient temperatures, vehicle load
and terrain.
How fail-safe cooling works
Standard cluster
Optional cluster
If the engine begins to overheat:
the engine coolant temperature gauge will move to the H (hot) area
(if your vehicle is equipped with analog gauges).
the engine coolant temperature gauge will illuminate all eight bars and
a tone will sound every five seconds for one minute (if your vehicle is
equipped with digital gauges).
the symbol will illuminate.
the Check Engine 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.
Maintenance and care
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