User Manual - Page 655

For 2001 XTERRA.

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The data, stored together with the DTC data, are called freeze frame data and displayed on CONSULT-II or
GST. The 1st trip freeze frame data can only be displayed on the CONSULT-II screen, not on the GST. For
details, see EC-679.
Only one set of freeze frame data (either 1st trip freeze frame data or freeze frame data) can be stored in the
ECM. 1st trip freeze frame data is stored in the ECM memory along with the 1st trip DTC. There is no prior-
ity for 1st trip freeze frame data and it is updated each time a different 1st trip DTC is detected. However, once
freeze frame data (2nd trip detection/MIL on) is stored in the ECM memory, 1st trip freeze frame data is no
longer stored. Remember, only one set of freeze frame data can be stored in the ECM. The ECM has the fol-
lowing priorities to update the data.
Priority Items
1
Freeze frame data Misfire DTC: P0300 - P0306
Fuel Injection System Function DTC: P0171, P0172, P0174, P0175
2 Except the above items (Includes A/T related items)
3 1st trip freeze frame data
For example, the EGR malfunction (Priority: 2) was detected and the freeze frame data was stored in the 2nd
trip. After that when the misfire (Priority: 1) is detected in another trip, the freeze frame data will be updated
from the EGR malfunction to the misfire. The 1st trip freeze frame data is updated each time a different mal-
function is detected. There is no priority for 1st trip freeze frame data. However, once freeze frame data is
stored in the ECM memory, 1st trip freeze data is no longer stored (because only one freeze frame data or
1st trip freeze frame data can be stored in the ECM). If freeze frame data is stored in the ECM memory and
freeze frame data with the same priority occurs later, the first (original) freeze frame data remains unchanged
in the ECM memory.
Both 1st trip freeze frame data and freeze frame data (along with the DTCs) are cleared when the ECM
memory is erased. Procedures for clearing the ECM memory are described in HOW TO ERASE EMISSION-
RELATED DIAGNOSTIC INFORMATION, EC-666.
SYSTEM READINESS TEST (SRT) CODE
NGEC0552S03
System Readiness Test (SRT) code is specified in Mode 1 of SAE J1979.
As part of enhanced emissions test for Inspection and Maintenance (I/M), certain states require that the sta-
tus of srt be used to indicate whether the ECM has completed self-diagnosis of major emission systems and
components. Completion must be verified in order for the emissions inspection to proceed.
If a vehicle is rejected for a State emissions inspection due to one or more SRT items indicating INCMP,
use the information in this service manual to set the SRT to CMPLT.
In most cases, the ECM will automatically complete its self-diagnosis cycle during normal usage and the SRT
status will indicate CMPLT for each application system. Once set as CMPLT, the SRT status remains
CMPLT until the self-diagnosis memory is erased.
Occasionally, certain portions of the self-diagnostic test may not be completed as a result of the customers
normal driving pattern and the SRT will indicate INCMP for these items.
NOTE:
The SRT will also indicate INCMP if the self-diagnosis memory is erased for any reason or if the ECM
memory power supply is interrupted for several hours.
If, during the state emissions inspection, the SRT indicates CMPLT for all test items, the inspector will con-
tinue with the emissions test. However, if the SRT indicates INCMP for one or more of the SRT items, the
vehicle is returned to the customer untested.
NOTE:
If MILis ON during the state emissions inspection, the vehicle is also returned to the customer untested even
though the SRT indicates CMPLT for all test items. Therefore, it is important to check SRT (CMPLT) and
DTC (No DTCs) before the inspection.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
VG33E
Emission-related Diagnostic Information (Contd)
EC-655
FE
CL
MT
AT
TF
PD
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
GI
MA
EM
LC
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