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EC-66Revision: August 2007
ON BOARD DIAGNOSTIC (OBD) SYSTEM
2004 QX56
A particular trouble code can be identified by the number of four-digit numeral flashes. The “zero” is indicated
by the number of ten flashes. The length of time the 1,000th-digit numeral flashes on and off is 1.2 seconds
consisting of an ON (0.6-second) - OFF (0.6-second) cycle.
The 100th-digit numeral and lower digit numerals consist of a 0.3-second ON and 0.3-second OFF cycle.
A change from one digit numeral to another occurs at an interval of 1.0-second OFF. In other words, the later
numeral appears on the display 1.3 seconds after the former numeral has disappeared.
A change from one trouble code to another occurs at an interval of 1.8-second OFF.
In this way, all the detected malfunctions are classified by their DTC numbers. The DTC 0000 refers to no mal-
function. (See EC-8, "
INDEX FOR DTC" )
How to Erase Diagnostic Test Mode II (Self-diagnostic Results)
The DTC can be erased from the back up memory in the ECM by depressing accelerator pedal. Refer to EC-
66, "How to Erase Diagnostic Test Mode II (Self-diagnostic Results)" .
If the battery is disconnected, the DTC will be lost from the backup memory within 24 hours.
Be careful not to erase the stored memory before starting trouble diagnoses.
OBD System Operation ChartUBS00GZV
RELATIONSHIP BETWEEN MIL, 1ST TRIP DTC, DTC, AND DETECTABLE ITEMS
When a malfunction is detected for the first time, the 1st trip DTC and the 1st trip freeze frame data are
stored in the ECM memory.
When the same malfunction is detected in two consecutive trips, the DTC and the freeze frame data are
stored in the ECM memory, and the MIL will come on. For details, refer to EC-49, "
Tw o Tr ip D e t e c t i o n
Logic" .
The MIL will go off after the vehicle is driven 3 times with no malfunction. The drive is counted only when
the recorded driving pattern is met (as stored in the ECM). If another malfunction occurs while counting,
the counter will reset.
The DTC and the freeze frame data will be stored until the vehicle is driven 40 times (driving pattern A)
without the same malfunction recurring (except for Misfire and Fuel Injection System). For Misfire and
Fuel Injection System, the DTC and freeze frame data will be stored until the vehicle is driven 80 times
(driving pattern C) without the same malfunction recurring. The “TIME” in “SELF-DIAGNOSTIC
RESULTS” mode of CONSULT-II will count the number of times the vehicle is driven.
The 1st trip DTC is not displayed when the self-diagnosis results in OK for the 2nd trip.
SUMMARY CHART
For details about patterns B and C under “Fuel Injection System” and “Misfire”, see EC-68 .
For details about patterns A and B under “Other”, see EC-70
.
*1: Clear timing is at the moment OK is detected.
*2: Clear timing is when the same malfunction is detected in the 2nd trip.Items Fuel Injection System Misfire Other
MIL (goes off) 3 (pattern B) 3 (pattern B) 3 (pattern B)
DTC, Freeze Frame Data (no
display)80 (pattern C) 80 (pattern C) 40 (pattern A)
1st Trip DTC (clear) 1 (pattern C), *1 1 (pattern C), *1 1 (pattern B)
1st Trip Freeze Frame Data
(clear)*1, *2 *1, *2 1 (pattern B)
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ON BOARD DIAGNOSTIC (OBD) SYSTEM
EC-67
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RELATIONSHIP BETWEEN MIL, DTC, 1ST TRIP DTC AND DRIVING PATTERNS FOR “MISFIRE
” , “FUEL INJECTION SYSTEM”
*1: When the same malfunction is
detected in two consecutive trips,
MIL will light up.*2: MIL will go off after vehicle is driven
3 times (pattern B) without any mal-
functions.*3: When the same malfunction is
detected in two consecutive trips, the
DTC and the freeze frame data will
be stored in ECM.
*4: The DTC and the freeze frame data
will not be displayed any longer after
vehicle is driven 80 times (pattern C)
without the same malfunction. (The
DTC and the freeze frame data still
remain in ECM.)*5: When a malfunction is detected for
the first time, the 1st trip DTC and
the 1st trip freeze frame data will be
stored in ECM.*6: The 1st trip DTC and the 1st trip
freeze frame data will be cleared at
the moment OK is detected.
*7: When the same malfunction is
detected in the 2nd trip, the 1st trip
freeze frame data will be cleared.*8: 1st trip DTC will be cleared when
vehicle is driven once (pattern C)
without the same malfunction after
DTC is stored in ECM.
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EC-68Revision: August 2007
ON BOARD DIAGNOSTIC (OBD) SYSTEM
2004 QX56
EXPLANATION FOR DRIVING PATTERNS FOR “MISFIRE
TION>”, “FUEL INJECTION SYSTEM”
Driving pattern B means the vehicle operation as follows:
All components and systems should be monitored at least once by the OBD system.
The B counter will be cleared when the malfunction is detected once regardless of the driving pattern.
The B counter will be counted up when driving pattern B is satisfied without any malfunction.
The MIL will go off when the B counter reaches 3. (*2 in OBD SYSTEM OPERATION CHART)
Driving pattern C means the vehicle operation as follows:
The following conditions should be satisfied at the same time:
Engine speed: (Engine speed in the freeze frame data) ±375 rpm
Calculated load value: (Calculated load value in the freeze frame data) x (1±0.1) [%]
Engine coolant temperature (T) condition:
When the freeze frame data shows lower than 70°C (158°F), T should be lower than 70°C (158°F).
When the freeze frame data shows higher than or equal to 70°C (158°F), T should be higher than or equal
to 70°C (158°F).
Example:
If the stored freeze frame data is as follows:
Engine speed: 850 rpm, Calculated load value: 30%, Engine coolant temperature: 80°C (176°F)
To be satisfied with driving pattern C, the vehicle should run under the following conditions:
Engine speed: 475 - 1,225 rpm, Calculated load value: 27 - 33%, Engine coolant temperature: more than 70°C
(158°F)
The C counter will be cleared when the malfunction is detected regardless of vehicle conditions above.
The C counter will be counted up when vehicle conditions above is satisfied without the same malfunction.
The DTC will not be displayed after C counter reaches 80.
The 1st trip DTC will be cleared when C counter is counted once without the same malfunction after DTC
is stored in ECM.
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ON BOARD DIAGNOSTIC (OBD) SYSTEM
EC-69
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RELATIONSHIP BETWEEN MIL, DTC, 1ST TRIP DTC AND DRIVING PATTERNS EXCEPT FOR
“MISFIRE ”, “FUEL INJECTION SYSTEM”
*1: When the same malfunction is
detected in two consecutive trips,
MIL will light up.*2: MIL will go off after vehicle is driven
3 times (pattern B) without any mal-
functions.*3: When the same malfunction is
detected in two consecutive trips, the
DTC and the freeze frame data will
be stored in ECM.
*4: The DTC and the freeze frame data
will not be displayed any longer after
vehicle is driven 40 times (pattern A)
without the same malfunction.
(The DTC and the freeze frame data
still remain in ECM.)*5: When a malfunction is detected for
the first time, the 1st trip DTC and
the 1st trip freeze frame data will be
stored in ECM.*6: 1st trip DTC will be cleared after
vehicle is driven once (pattern B)
without the same malfunction.
*7: When the same malfunction is
detected in the 2nd trip, the 1st trip
freeze frame data will be cleared.
SEF 3 93 SD
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EC-70Revision: August 2007
ON BOARD DIAGNOSTIC (OBD) SYSTEM
2004 QX56
EXPLANATION FOR DRIVING PATTERNS EXCEPT FOR “MISFIRE
DETERIORATION>”, “FUEL INJECTION SYSTEM”
The A counter will be cleared when the malfunction is detected regardless of (1) - (4).
The A counter will be counted up when (1) - (4) are satisfied without the same malfunction.
The DTC will not be displayed after the A counter reaches 40.
Driving pattern B means the vehicle operation as follows:
All components and systems should be monitored at least once by the OBD system.
The B counter will be cleared when the malfunction is detected once regardless of the driving pattern.
The B counter will be counted up when driving pattern B is satisfied without any malfunctions.
The MIL will go off when the B counter reaches 3 (*2 in OBD SYSTEM OPERATION CHART).
AEC5 74
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TROUBLE DIAGNOSIS
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TROUBLE DIAGNOSISPFP:00004
Trouble Diagnosis IntroductionUBS00GZW
INTRODUCTION
The engine has an ECM to control major systems such as fuel con-
trol, ignition control, idle air control system, etc. The ECM accepts
input signals from sensors and instantly drives actuators. It is essen-
tial that both input and output signals are proper and stable. At the
same time, it is important that there are no malfunctions such as vac-
uum leaks, fouled spark plugs, or other malfunctions with the engine.
It is much more difficult to diagnose an incident that occurs intermit-
tently rather than continuously. Most intermittent incidents are
caused by poor electric connections or improper wiring. In this case,
careful checking of suspected circuits may help prevent the replace-
ment of good parts.
A visual check only may not find the cause of the incidents. A road
test with CONSULT-II (or GST) or a circuit tester connected should
be performed. Follow EC-72, "
WORK FLOW" .
Before undertaking actual checks, take a few minutes to talk with a
customer who approaches with a driveability complaint. The cus-
tomer can supply good information about such incidents, especially
intermittent ones. Find out what symptoms are present and under
what conditions they occur. A Diagnostic Worksheet like the example
on EC-75
should be used.
Start your diagnosis by looking for conventional malfunctions first.
This will help troubleshoot driveability malfunctions on an electroni-
cally controlled engine vehicle.
MEF036D
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EC-72Revision: August 2007
TROUBLE DIAGNOSIS
2004 QX56
WORK FLOW
Flow Chart
*1 If time data of “SELF-DIAG
RESULTS” is other than [0] or [1t],
perform EC-127, "
TROUBLE DIAG-
NOSIS FOR INTERMITTENT INCI-
DENT" .*2 If the incident cannot be verified, per-
form EC-127, "
TROUBLE DIAGNO-
SIS FOR INTERMITTENT
INCIDENT" .*3 If the on board diagnostic system
cannot be performed, check main
power supply and ground circuit.
Refer to EC-128, "POWER SUPPLY
AND GROUND CIRCUIT" .
*4 If malfunctioning part cannot be
detected, perform EC-127, "
TROU-
BLE DIAGNOSIS FOR INTERMIT-
TENT INCIDENT" .*5EC-59, "
Driving Pattern"*6EC-123, "TROUBLE DIAGNOSIS -
SPECIFICATION VALUE"
PBIB1043E
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TROUBLE DIAGNOSIS
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Description for Work Flow
STEP DESCRIPTION
STEP IGet detailed information about the conditions and the environment when the incident/symptom occurred using the
EC-74, "
DIAGNOSTIC WORKSHEET" .
STEP IIBefore confirming the concern, check and write down (print out using CONSULT-II or GST) the (1st trip) DTC and the
(1st trip) freeze frame data, then erase the DTC and the data. (Refer to EC-62, "
HOW TO ERASE EMISSION-
RELATED DIAGNOSTIC INFORMATION" .) The (1st trip) DTC and the (1st trip) freeze frame data can be used
when duplicating the incident at STEP III & IV.
If the incident cannot be verified, perform EC-127, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
Study the relationship between the cause, specified by (1st trip) DTC, and the symptom described by the customer.
(The Symptom Matrix Chart will be useful. See EC-84, "
Symptom Matrix Chart" .)
Also check related service bulletins for information.
STEP IIITry to confirm the symptom and under what conditions the incident occurs.
The DIAGNOSTIC WORK SHEET and the freeze frame data are useful to verify the incident. Connect CONSULT-II
to the vehicle in DATA MONITOR (AUTO TRIG) mode and check real time diagnosis results.
If the incident cannot be verified, perform EC-127, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
If the malfunction code is detected, skip STEP IV and perform STEP V.
STEP IVTry to detect the (1st trip) DTC by driving in (or performing) the DTC Confirmation Procedure. Check and read the (1st
trip) DTC and (1st trip) freeze frame data by using CONSULT-II or GST.
During the (1st trip) DTC verification, be sure to connect CONSULT-II to the vehicle in DATA MONITOR (AUTO TRIG)
mode and check real time diagnosis results.
If the incident cannot be verified, perform EC-127, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT" .
In case the DTC Confirmation Procedure is not available, perform the Overall Function Check instead. The (1st trip)
DTC cannot be displayed by this check, however, this simplified check is an effective alternative.
The NG result of the Overall Function Check is the same as the (1st trip) DTC detection.
STEP VTake the appropriate action based on the results of STEP I through IV.
If the malfunction code is indicated, proceed to TROUBLE DIAGNOSIS FOR DTC PXXXX.
If the normal code is indicated, proceed to the BASIC INSPECTION. (Refer to EC-79, "
Basic Inspection" .) Then per-
form inspections according to the Symptom Matrix Chart. (Refer to EC-84, "
Symptom Matrix Chart" .)
STEP VIIdentify where to begin diagnosis based on the relationship study between symptom and possible causes. Inspect the
system for mechanical binding, loose connectors or wiring damage using (tracing) “Harness Layouts”.
Gently shake the related connectors, components or wiring harness with CONSULT-II set in “DATA MONITOR
(AUTO TRIG)” mode.
Check the voltage of the related ECM terminals or monitor the output data from the related sensors with CONSULT-II.
Refer to EC-96, "
ECM Terminals and Reference Value" , EC-118, "CONSULT-II Reference Value in Data Monitor" .
The Diagnostic Procedure in EC section contains a description based on open circuit inspection. A short circuit
inspection is also required for the circuit check in the Diagnostic Procedure. For details, refer to “Circuit Inspection” in
GI-27, "
How to Perform Efficient Diagnosis for an Electrical Incident" .
Repair or replace the malfunction parts.
If malfunctioning part cannot be detected, perform EC-127, "
TROUBLE DIAGNOSIS FOR INTERMITTENT INCI-
DENT" .
STEP VIIOnce you have repaired the circuit or replaced a component, you need to run the engine in the same conditions and
circumstances which resulted in the customer's initial complaint.
Perform the DTC Confirmation Procedure and confirm the normal code [DTC No. P0000] is detected. If the incident is
still detected in the final check, perform STEP VI by using a method different from the previous one.
Before returning the vehicle to the customer, be sure to erase the unnecessary (already fixed) (1st trip) DTC in ECM
and TCM (Transmission control module). (Refer to EC-62, "
HOW TO ERASE EMISSION-RELATED DIAGNOSTIC
INFORMATION" and AT- 4 0 , "HOW TO ERASE DTC" .)