AFO Enable Circuit Status: Display shows OK, OPEN, SHORT TO GND or SHORT TO VOLTS. This display
indicates the monitored status of the output driver circuit for this output.
OK should always be indicated unless a circuit fault is monitored.
AFO Signal: Display shows PCM or AFECM. This display monitors the vehicles
powertrain control module (PCM) Alternative Fuels Operation (AFO) Signal
circuit. Alternative fuel operation is requested when the alternative fuels
ECM grounds the AFO Signal circuit to the PCM. This display
is received through serial data from the PCM.
AFO Signal Command: Display shows PCM or AFECM. This display monitors the alternative
fuels ECM AFO Command circuit output driver. Alternative fuel operation is
requested when the AF ECM grounds the AFO Signal circuit to the PCM.
Alternative Fuel Level: Display shows fuel level from 0% to 100%. This display indicates
the fuel level signal being sent by the alternative fuels ECM. The alternative
fuels ECM monitors the fuel tank pressure sensor and the fuel tank temperature
sensor values in order to determine the usable CNG fuel level.
Alternative Fuel Mileage Log: Display shows miles the vehicle has operated using alternative
fuel.
(Alt. Fuel) Fuel Pump Relay Command: Display shows ON or OFF. The display indicates the commanded state
of the AF Fuel Pump relay. The gasoline fuel pump relay power circuit is
routed through the AF Fuel Pump relay. Whenever the engine
is operating on CNG the alternative fuels ECM commands the AF Fuel
pump relay ON, opening the gasoline fuel pump relay power
circuit. The alternative fuels ECM opens the gasoline fuel pump
relay power circuit in order to prevent unnecessary gasoline
fuel pump operation.
Alternative Fuel Run Time Log: Display shows Hours: minutes: seconds. This display shows the
amount of time the engine has operated using alternative fuel.
BARO: Display shows the BARO in Kpa from 11 to 105. The BARO reading
is taken at key ON using the MAP sensor and is also corrected
at wide open throttle (WOT). Multiply your current, local,
barometric pressure by 3.386 to obtain a BARO value that should
be within 2 Kpa of the displayed value.
Battery Voltage: Display shows voltage from 0 to 25.5. This display indicates the
system voltage measured by the alternative fuels ECM at the battery feed
terminal.
ECT Sensor: Display shows the temperature of the engine coolant from -40°
to 155°C (-40° to 311°F) and the sensor voltage from
0.0 to 5.00.
EGR Position Sensor: Display shows the position of the EGR valve sensor voltage from
0.0 to 5.00.
Engine Load: Display shows engine load in percent from 0 to 100. Engine load
is calculated by the alternative fuels ECM by engine speed and manifold
absolute pressure. Engine load should increase with an increase in RPM
and MAP.
Engine Run Time: Display shows Hours: minutes: seconds. Engine run time measures
how long the engine has been running during this ignition cycle. When the
engine is turned OFF, the timer is reset to zero.
Engine Speed: Display shows crankshaft rotation speed in revolutions per minute
(RPM) from 0 to 16384. The maximum engine speed is limited to 5500 RPM
by the alternative fuels ECM during alternative fuel operation.
EVAP Purge Solenoid Command: Display shows percent. This display monitors the vehicles powertrain
control module (PCM) EVAP Purge Solenoid Control circuit.
Fuel Gauge Circuit Status: Display shows OK, OPEN, SHORT TO GND or SHORT TO VOLTS. This display
indicates the monitored status of the output driver circuit for this output.
OK should always be indicated unless a circuit fault is monitored.
Fuel Gauge Select Switch: Display shows Depressed or Released. This display monitors the
vehicles powertrain control module (PCM) Fuel Gauge Select Switch
signal circuit. When depressed, the fuel gauge select switch will command
the PCM to display the fuel level of the non-operating fuel system for about
10 seconds. This display is received through serial data from the PCM.
Fuel Indicator Lamp Command: Display shows ON or OFF. This display monitors the vehicles powertrain
control module (PCM) Fuel Indicator Lamp (FIL) control circuit. The FIL is
commanded ON when the engine is operating on gasoline. This display is
received through serial data from the PCM.
Fuel Rail Pressure Sensor: Display shows voltage from 0.0 to 5.0 and pressure from 0 to 772 kPa
(0 to 112 psi). This display indicates the CNG fuel rail pressure.
The alternative fuels ECM monitors the fuel rail pressure (FRP) sensor
in order to calculate the correct fuel injector pulse width.
Fuel Rail Temperature Sensor: Display shows voltage from 0.0 to 5.0 and temperature from -40°C
to 150°C (-40°F to 302°F). This display indicates the
temperature of the CNG fuel within the fuel rail. The alternative
fuels ECM monitors the fuel rail temperature (FRT) sensor in order
to calculate the correct fuel injector pulse width.
Fuel Tank Pressure Sensor: Display shows voltage from 0.0 to 5.0 and pressure from 0 to 4064 psi.
This display indicates the CNG fuel tank pressure. The alternative fuels
ECM monitors the fuel tank pressure (FTP) sensor and the fuel tank temperature
(FTT) sensor in order to calculate the correct CNG fuel level
remaining in the tank.
Fuel Temperature Sensor: Display shows voltage from 0.0 to 5.0 and temperature from -40°C
to 150°C (-40°F to 302°F). This display indicates the
temperature of the CNG fuel within the fuel tank. The alternative
fuels ECM monitors the fuel tank pressure (FTP) sensor and the fuel
tank temperature (FTT) sensor in order to calculate the correct
CNG fuel level remaining in the tank. The FTT sensor is a
non-serviceable part of the high pressure lock-off solenoid.
Gasoline Fuel Mileage Log: Display shows miles the vehicle has operated using gasoline fuel.
Gasoline Fuel Run Time Log: Display shows Hours: minutes: seconds. This display shows the
amount of time the engine has operated using gasoline fuel.
High Pressure Lockoff Solenoid Command: Display shows FUEL FLOW or NO FUEL FLOW. This display indicates
the commanded state of the high pressure lock-off solenoid. The alternative
fuels ECM opens the HPL for one second at EVERY ignition
ON in order to supply a prime pulse to the CNG fuel system.
HO2S Bank 1 Sensor 1: Display shows voltage from 0.0 to 1.1 volts. This display
indicates the voltage of the O2 sensor High signal circuit. With a COLD O2
sensor the signal circuit BIAS voltage of about 451 mV
should be displayed. The oxygen sensor will produce voltage
in relation to exhaust oxygen content once the oxygen sensor
reaches operating temperature. High exhaust oxygen content,
or LEAN conditions, will produce low voltage - 100 mV.
Low exhaust oxygen content, or RICH conditions, will produce
high voltage -- 900 mV. With the oxygen sensor at operating
temperature and the engine in Closed Loop operation the oxygen
sensor voltage should rapidly fluctuate between low and high
voltage.
HO2S Bank 2 Sensor 1: Display shows voltage from 0.0 to 1.1 volts. This display
indicates the voltage of the O2 sensor High signal circuit. With a COLD O2
sensor the signal circuit BIAS voltage of about 451 mV
should be displayed. The oxygen sensor will produce voltage
in relation to exhaust oxygen content once the oxygen sensor
reaches operating temperature. High exhaust oxygen content,
or LEAN conditions, will produce low voltage - 100 mV.
Low exhaust oxygen content, or RICH conditions, will produce
high voltage -- 900 mV. With the oxygen sensor at operating
temperature and the engine in Closed Loop operation the oxygen
sensor voltage should rapidly fluctuate between low and high
voltage.
HPL Solenoid Output Circuit Status: Display shows OK, OPEN, SHORT TO GND or SHORT TO VOLTS. This display
indicates the monitored status of the output driver circuit for this output.
OK should always be indicated unless a circuit fault is monitored.
IAT Sensor: Display shows the temperature of the intake manifold air from -40°
to 155°C (-40° to 311°F) and the sensor voltage from
0.0 to 5.00.
Ignition 0: Display shows voltage from 0 to 25.5. This display indicates the
system voltage measured by the alternative fuels ECM at the Ignition 0 terminal.
Injector PWM Average Bank 1: Display shows pulse width in milliseconds. This display indicates
the average ON time that the alternative fuels ECM is commanding the bank
1 CNG fuel injectors.
Injector PWM Average Bank 2: Display shows pulse width in milliseconds. This display indicates
the average ON time that the alternative fuels ECM is commanding the bank
2 CNG fuel injectors.
Long Term FT Bank 1: Display shows percentage from -100% to 100%. The center
position for the long term fuel trim is 0%. The long term fuel trim is
based on short term fuel trim learned values. It is stored
in memory blocks of the long term memory according to MAP
and RPM values. A percentage greater than 0% indicates
that time is being added to the injector pulse width, increasing
the amount of fuel to the engine. A percentage less than 0%
indicates time is being subtracted from the injector pulse width,
reducing the amount fuel to the engine. A value of 0% indicates
no compensation is required to operate the engine at the desired
16.8 to 1 air/fuel ratio.
Long Term FT Bank 2: Display shows percentage from -100% to 100%. The center
position for the long term fuel trim is 0%. The long term fuel trim is
based on short term fuel trim learned values. It is stored
in memory blocks of the long term memory according to MAP
and RPM values. A percentage greater than 0% indicates
that time is being added to the injector pulse width, increasing
the amount of fuel to the engine. A percentage less than 0%
indicates time is being subtracted from the injector pulse width,
reducing the amount fuel to the engine. A value of 0% indicates
no compensation is required to operate the engine at the desired
16.8 to 1 air/fuel ratio.
Loop Status: Display shows OPEN LOOP or CLOSED LOOP. Closed Loop displayed
indicates that the alternative fuels ECM is controlling fuel delivery according
to oxygen sensor voltage. In Open Loop, the alternative fuels
ECM ignores the oxygen sensor voltage and bases the amount
of fuel to be delivered on other input sensors. At extremely
high ambient temperatures or when towing a trailer, it is possible
for the system to remain in Open Loop operation in order to
control catalytic converter temperatures.
Low Pressure Lockoff Solenoid Command: Display shows FUEL FLOW or NO FUEL FLOW. This display indicates
the commanded state of the low pressure lock-off solenoid. During alternative
fuel operation conditions the LPL remains closed until at
least 25 RPM is monitored by the alternative fuels ECM.
LPL Solenoid Output Circuit Status: Display shows OK, OPEN, SHORT TO GND, SHORT TO VOLTS or OVER TEMP.
This display indicates the monitored status of the output driver circuit
for this output. OK should always be indicated unless a circuit
fault is monitored.
MAF Sensor: Display shows the amount of airflow entering the engine in grams
per second (g/s) from 0 to 512 and in frequency from 0 to 31,999 Hz.
The MAF sensor produces a frequency signal equal to 2.4 g/s whenever the
ignition is ON and no airflow is present. The 2.4 g/s signal is necessary
in order to detect circuit faults.
MAP Sensor: Display shows manifold pressure in Kilo Pascals (Kpa) from 10
to 104 and voltage from 0 to 5.0. At key ON , engine not running, the MAP
value will reflect barometric pressure. To check for an accurate
MAP reading multiply your local barometric pressure by 3.386
to obtain a map value that should be within 2 Kpa of
displayed value at key ON , engine not running.
(PCM) MIL Command: Display shows ON or OFF. The malfunction indicator lamp (MIL) is
controlled by both the alternative fuels ECM and the gasoline powertrain control
module (PCM). This display indicates ON whenever the PCM commands the
MIL ON. The internal circuitry of the alternative fuels ECM monitors,
but does not affect, the PCM operation of the MIL. The MIL
is illuminated if either module has detected a problem that
affects vehicle emissions, driveabillity or could cause powertrain
damage. The PCM illuminates the MIL when the ignition is ON
and the engine OFF in order to perform a bulb test.
(Alt. Fuel) MIL Command: Display shows ON or OFF. The malfunction indicator lamp (MIL) is
controlled by both the alternative fuels ECM and the gasoline powertrain control
module (PCM). This display indicates ON whenever either module commands
the MIL ON. The internal circuitry of the alternative fuels ECM
monitors, but does not affect, the PCM operation of the MIL.
The MIL is illuminated if either module has detected a problem
that affects vehicle emissions, driveabillity or could cause
powertrain damage. The PCM illuminates the MIL when the ignition
is ON and the engine OFF in order to perform a bulb test.
MIL Output CKT Status: Display shows OK, OPEN, SHORT TO GND, SHORT TO VOLTS or OVER TEMP.
This display indicates the monitored status of the output driver circuit
for this output. OK should always be indicated unless a circuit
fault is monitored.
Reference Voltage High: Display shows voltage from 0.0 to 5.2 volts. This display
indicates the voltage monitored by the alternative fuels ECM from the gasoline
PCM 5 volt sensor supply circuit.
Reference Voltage Low: Display shows voltage from 0.0 to 5.2 volts. This display
indicates the voltage monitored by the alternative fuels ECM from the gasoline
PCM 5 volt sensor ground circuit.
Short Term FT Bank 1: Display shows percentage from -100% to 99%. The center
position for the short term fuel trim is 0%. A percentage greater than 0%
indicates that time is being added to the injector pulse
width, increasing the amount of fuel to the engine to compensate
for a lean condition sensed by the Bank 1 oxygen sensor.
A percentage less than 0% indicates time is being subtracted
from the injector pulse width reducing the amount of fuel
to the engine to compensate for a rich condition sensed by the
Bank 1 oxygen sensor. A value of 0% indicates no compensation
is required to operate the engine at the desired 16.8 to 1 air/fuel
ratio.
Short Term FT Bank 2: Display shows percentage from -100% to 99%. The center
position for the short term fuel trim is 0%. A percentage greater than 0%
indicates that time is being added to the injector pulse
width, increasing the amount of fuel to the engine to compensate
for a lean condition sensed by the Bank 2 oxygen sensor.
A percentage less than 0% indicates time is being subtracted
from the injector pulse width reducing the amount of fuel
to the engine to compensate for a rich condition sensed by the
Bank 2 oxygen sensor. A value of 0% indicates no compensation
is required to operate the engine at the desired 16.8 to 1 air/fuel
ratio.
TP Sensor: Display shows throttle angle from 0 to 100% and sensor voltage
from 0.0 to 5.0 volts. The % display indicates the throttle angle
opening. Throttle closed is 0% and fully open is 100%. The alternative fuels
ECM learns the closed throttle position whenever the TP sensor voltage
is below about 0.9 volts. Learning the closed throttle
position is necessary in order to adjust for production tolerances.
The voltage display indicates the throttle angle opening.Throttle
closed is about 0.5 volts and fully open is about 4.0 volts.
TR Switch: Display shows the position of the trans range (TR) switch.
Vehicle Speed Sensor: Display shows vehicle speed from 0 km/h (0 mph) to
255 km/h (155 mph). The maximum vehicle speed is limited to
107 mph by the alternative fuels ECM during alternative
fuel operation.