ELECTRICAL
10.5
condition then the regulator will remain off, as the
minimum battery requirement will not be met. The
regulator will not turn on unless there exists battery
voltage in excess of the minimum battery voltage
requirement. Therefore, do not attempt to charge
dead batteries using the vehicle’s charging system.
NOTE: COIL 1 has a resisitance to ground.
Battery Protected Output
The battery protected output (BAT_PROT) provides
solid--state--circuit--breaker (SSCB) outputs and
enables most of the functions on the PDM. The
BAT_PROT outputmust be routed only to thevehicle
key/run switch for proper power up sequence.
BAT_PROT is enabled when the key/run switch
connects the BAT_PROT output to loads (must
include RUN input). When RUN input goes high, the
micro--controllerwillremain’ON’until RUN input goes
low by disconnection of the BAT_PROT via the key
switch or on/off switch. It will remain ’ON’ for 5
seconds before turning off The BAT_PROT output is
protected from overloads and short circuits. If this
occurs, the outputturns off. Once tripped, theSSCBs
can be reset by removing the overload or cycling the
key/run switches. The SSCBs will trip again if the
issue causing the overload is not removed.
Engine Temperature Controller
The engine temperature controller has several
features and twoouputs: HOT INDICATORandF AN.
The engine hot output is low and sinks the indicator
signal to ground. The fan output is avtive high and
sources battery power to turn on the fan. The
controller’ s primary function is to control the fan
motor. The fan motor is turned on and off at pre--set
resistancesasdeterminedbytheenginetemperature
thermistor .The FANoutput is protected against short
circuit and overload. If the fan current exceeds the
overload limit longer than the time allowed for inrush,
the fanwill shut off andthe HOT INDICATOR will turn
on. After a delay, the FAN output will then reset itself
and turn on again. If the overload persists, the
controller will cycle the FAN output on and off at set
intervaluntilthe overloadis removed.Ifthemaximum
temperature of the switching device is exceeded the
fan output will turnoff. Thefan will cycle on and off as
previously described until the device temperature
drops. The FAN output driver also monitors to see if
the fanis connectedduring’ON’ state only. If theFAN
output is open circuit upon power up, the engine
temperature controller will activate the hot indicator.
If the engine temperature exceeds the engine hot
thermistor limit, or detects a fan overload condition,
the hot indicator will activate. The controller also
contains provisions for detecting an open or shorted
thermistor .A thermistorfaultwill causetheenginehot
indicator and FAN output to activate.
Accessory Power:
The ACC_PWR switchuses asmart high--sidepower
switch. It is enabled when the RUN input is activated
and disabled when it’s removed. If the output current
exceeds the short--circuit limit, the output current will
be reduced until the ACC_PWR thermally shuts
down. ACC_PWR will automatically turn back on
when it has cooled, based on thermal recovery. Once
tripped, this ouput will remain off until the key switch
is cycled on and off again.
Lights Output
The LIGHTS output uses a smart high--side power
switch. TheLIGHTS relayoutputis enabled when the
RUN input is activated and disabled when it’s
removed. If the maximum output current threshold is
exceeded, the output current will be reduced until the
LIGHTS circuit thermally shuts down. Once tripped,
this ouput will remain off until the key switch is cycled
on and off again.
HOT Indicator Output
The HOT Indicator output uses a low--side power
switch ’smart FET’ that indicates when thethermistor
input exceeds the values prorammed in the PDM. It
also indicates a stalled or open fan condition. The
output is protected against shorts to battery,
over--load, over--voltage and over--temperature
conditions.
Starter Lockout
Starter Lockout monitors the brake input and
transmission signal to determine if the STARTER
output FET will enable a ground path for the starter
solenoid. The output is enabled if either the BRAKE
input is high or the TRANS signal voltage indicates
PARK or NEUTRAL. TRANS voltage is based on a
5Vdc power supply with a 220--ohm load, with
24--ohm for park and 160--ohm for neutral. RUN input
must be enabled for the starter lockout to function.
This output is overload and short circuit protected by
the BAT--PROT output on the high side.
Reverse Polarity Protection
The reverse polarity protection circuit is in series with
thebatterypositiveinputof the PDM.Itallowsforward
current to flow with little voltage drop. When the
battery terminals are connected in reverse, the
protectionswitchisforcedoff, interruptinganycurrent
flow other than --2mA of bias current.
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