Daewoo Nubira User Manual page 618

Failed Last Test
This message display indicates that the last diagnostic
test failed for the selected DTC. For type A and type B
DTCs, this message will be displayed during subsequent
ignition cycles until the test passes or DTCs are cleared.
For type C and type D DTCs, this message will clear when
the ignition is cycled.
Failed Since Clear
This message display indicates that the DTC has failed at
least once within the last 40 warm–up cycles since the last
time DTCs were cleared.
Failed This Ig. (Failed This Ignition)
This message display indicates that the diagnostic test
has failed at least once during the current ignition cycle.
This message will clear when DTCs are cleared or the igni-
tion is cycled.
History DTC
This message display indicates that the DTC has been
stored in memory as a valid fault. A DTC displayed as a
History fault may not mean that the fault is no longer pres-
ent. The history description means that all the conditions
necessary for reporting a fault have been met (maybe
even currently), and the information was stored in the con-
trol module memory.
MIL Requested
This message display indicates that the DTC is currently
causing the MIL to be turned ON. Remember that only
type A and type B DTCs can request the MIL. The MIL re-
quest cannot be used to determine if the DTC fault condi-
tions are currently being experienced. This is because the
diagnostic executive will require up to three trips during
which the diagnostic test passes to turn OFF the MIL.
Not Run Since CI (Not Run Since Cleared)
This message display indicates that the selected diagnos-
tic test has not run since the last time DTCs were cleared.
Therefore, the diagnostic test status (passing or failing) is
unknown. After DTCs are cleared, this message will con-
tinue to be displayed until the diagnostic test runs.
Not Run This Ig. (Not Run This Ignition)
This message display indicates that the selected diagnos-
tic test has not run during this ignition cycle.
Test Ran and Passed
This message display indicates that the selected diagnos-
tic test has done the following:
S
Passed the last test.
S
Run and passed during this ignition cycle.
S
Run and passed since DTCs were last cleared.
If the indicated status of the vehicle is "Test Ran and
Passed" after a repair verification, the vehicle is ready to
be released to the customer.
DAEWOO V–121 BL4
ENGINE CONTROLS 1F – 415
If the indicated status of the vehicle is "Failed This Ignition"
after a repair verification, then the repair is incomplete and
further diagnosis is required.
Prior to repairing a vehicle, status information can be used
to evaluate the state of the diagnostic test, and to help
identify an intermittent problem. The technician can con-
clude that although the MIL is illuminated, the fault condi-
tion that caused the code to set is not present. An intermit-
tent condition must be the cause.
PRIMARY SYSTEM–BASED
DIAGNOSTICS
There are primary system–based diagnostics which eval-
uate system operation and its effect on vehicle emissions.
The primary system–based diagnostics are listed below
with a brief description of the diagnostic function:
Oxygen Sensor Diagnosis
The fuel control Oxygen Sensor (O2S) is diagnosed for
the following conditions:
S
Slow response.
S
Response time (time to switch R/L or L/R).
S
Inactive signal (output steady at bias voltage
approx. 450 mv).
S
Signal fixed high.
S
Signal fixed low.
The catalyst monitor Heated Oxygen Sensor (HO2S) is
diagnosed for the following conditions:
S
Heater performance (time to activity on cold start).
S
Signal fixed low during steady state conditions or
power enrichment (hard acceleration when a rich-
mixture should be indicated).
S
Signal fixed high during steady state conditions or
deceleration mode (deceleration when a lean mix-
ture should be indicated).
S
Inactive sensor (output steady at approximately 438
mv).
If the oxygen sensor pigtail wiring, connector or terminal
are damaged, the entire oxygen sensor assembly must be
replaced. Do not attempt to repair the wiring, connector or
terminals. In order for the sensor to function properly, it
must have clean reference air provided to it. This clean air
reference is obtained by way of the oxygen sensor wire(s).
Any attempt to repair the wires, connector or terminals
could result in the obstruction of the reference air and de-
grade oxygen sensor performance.
Misfire Monitor Diagnostic Operation
The misfire monitor diagnostic is based on crankshaft
rotational velocity (reference period) variations. The pow-
ertrain control module (PCM)/engine controlmodule
(ECM) determines crankshaft rotational velocity using the
Crankshaft Position (CKP) sensor and the Camshaft Posi-
tion (CMP) sensor. When a cylinder misfires, the crank-
shaft slows down momentarily. By monitoring the CKP and
CMP sensor signals, the PCM/ECM can calculate when
a misfire occurs.