Operation Section
-111-
Table a. MI-04 Diagnostic Fault Codes (Flash Codes)
DFC
Probable Fault
Action
Corrective Action, First Check
73 AFRTrimValveUpperDC
FTV duty cycle at high (rich) limit
(Expected fault when FTV connector
is unplugged)
Stored Fault Code
(MIL, Disable
Adaptive learns)
Engine measured Air/Fuel ratio at the
O2 sensor is excessively rich
Check FTV connector wiring for an
open circuit
z
Check N-CA55-500-TR mixer
for heavy end build-up and
operation (see mixer section)
z
Check N2001 secondary for
operation (see N2001
Regulator section)
74 O2SensorSwitching
O2 sensor is not switching across
the reference AFR voltage
Stored Fault Code
(MIL, Disable
Adaptive learns)
Note : If LP-Gas fuel in LP tank is not
enough, this fault code can be set. If
LP tank is frozen, this fault code can
be set, too. It is not system trouble.
Check the FTV for proper operation
Check FTV Hose Connections
77 OxygenSensorInputHigh
O2 sensor SECM driver signal is
shorted to power
Stored Fault Code
(MIL, Disable
Adapts)
Check if O2 sensor is shorted to
+5VDC or Battery.
(AFRTrimValveLowerDC
fault
should also occur)
