Operating instructions

ENGINE ELECTRICAL
Alternator Controlled Switch "ACS"
Shown is the (ACS) for the 1993 to current 500 EFI
systems. The ACS controls voltage from the
alternator by rectifying from
AC to DC voltage current
to charge the battery.
It also supplies the ECU with a
12vDC battery voltage signal
to indicate that the
engine's crankshaft is turning.
The ACS eliminates
the need for the
"Ready" light system reset as used on
previous
500 EFI models. NOTE: Even if the key
switch and kill switch are in the
"off' position, the ACS
will power up the system if the crankshaft is turned.
(See also page 4.40, Power up testing.)
Test Procedure
With ignition in the on or run position, crank engine over slowly. You will hear the fuel pump run for approximately
five seconds. This tells you the
ACS is working. If the fuel pump doesn't work when cranking, disconnect ECU
wire harness and reconnect to reset ECU. Crank engine again. If fuel pump won't start working, unplug the
harness at the
ECU and check Orange/Black wire PIN #11 on the ECU harness. Battery voltage should be
present when cranking engine.
NOTE: You can also use the select monitor to determine if the ECU is getting
power.
If the select monitor display lights up, then the ECU is getting power, check the ACS wire at the ECU plug.
CAUTION: Take care not to distort the pin with your tester lead. If no voltage is present, reset ECU and check
Orange/Black lead at
ACS unit. If no voltage is present, check for alternator output or loose connections. If
alternator output is OK, replace ACS.
NOTE: 1994 to current sao's will use a five wire ACS LR36. The extra wire is for a center tap alternator.
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Cold Starting
Whenever the engine is being cold started, the ECU will select a special "start-up" mode. This will occur any time
the engine is being cold started; for example, any Type
I system which has been "key off' long enough for the self
shut-off timer to power down the system, or a Type
II system which has had the engine stopped long enough for
the ready light to go off. After turning on the ignition key to reset the system, the fuel pump will run from three to five
seconds to pressurize the system. When the
ECU sees the first ignition pulse it provides a longer than normal
"prime" pulse to the injectors to inject enough fuel into the engine for starting. On 1993 and later Type II systems,
there is no ready light or ignition key reset. The pump
mayor may not run for the 3-5 second period depending on
how long the engine has been off.
In all systems, the "prime" pulse only occurs if the pump runs for the 3-5 second
period.
Once the engine is running the ECU provides a rich cold engine mixture while the engine is warming up. It uses the
engine temperature sensors as an indicator of when the engine is warm enough to start decreasing the fuel to air
ratio.
If the key is turned off, the ECU provides power to the self shut-off relay for from ten seconds to ten minutes,
depending upon the system type, and will not repeat the fuel system pressurizing and prime pulse during that time.
Once the self shut-off sequence has expired, the engine will have had sufficient time to cool and the ECU will again
repeat the cold start sequence.
In Type I systems only, during times of severely hard running or in very warm weather if the engine crankcase
should approach a temperature which might result in engine damage the
ECU will provide additional fuel to the
engine for cooling. When the crankcase temperature sensor indicates a temperature of approximately
100°C, the
ECU will lengthen the pulse time and cause an over-rich condition which will cool the engine. As soon as the
engine temperature returns to normal, the ECU will return to the original map.
If the engine should become flooded during starting, it can be cleaned out by holding the throttle wide open while
turning the engine over.
If the engine is not running, and the throttle is open more than 60°, no fuel will be injected.
The engine will start and will begin receiving fuel from injection when the engine exceeds
800 RPM, or when the
throttle position goes under
60°. The engine should then clean out and run normally.
In Type II systems, the engine is protected against overheating by the engine coolant sensor. If the engine coolant
reaches a threshold
(85°C 1993 and later, else 1 OO ° G) the 'temp" light on the dash will begin to flash. If the engine
coolant temperature continues to increase, the light will begin to blink faster. When the light blinks fast, the
ECU
adds fuel to enrich the mixture and to help prevent engine damage. The fuel will continue to be added until the light
stops blinking.
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4.42