INFINITI QX56 2007 Factory Service Manual

LAN-20
< SERVICE INFORMATION >[CAN FUNDAMENTAL]
TROUBLE DIAGNOSES WORK FLOW
• For the details, refer to LAN-54, "Data Sheet".
CREATE DIAGNOSIS SHEET
NOTE:
Be sure to use the diagnosis sheet for the correct CAN system type.
Print Diagnosis Sheet
Print the diagnosis sheet for the applicable CAN system type.
Check of Received Data
Check the created data sheet for missing information.
SKIB8722E

TROUBLE DIAGNOSES WORK FLOW
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• For abbreviations, refer to LAN-37, "Abbreviation List".
DETECT THE ROOT CAUSE
Identify the root cause using the created diagnosis sheet.
Identifying the root cause• Draw a line on the diagnosis sheet to indicate the possible cause. Narrow the search.
NOTE:
• Color-code when drawing lines.
• Do not draw a line onto a existing line.
• Drawing a line is not necessary if the circuit is shorted. Refer to "Present Error — Short Circuit —", "Past
Error — Short Circuit —".
Refer to the following for details of the trouble diagnosis procedure.
• "Present Error — Open Circuit —"
• "Present Error — Short Circuit —"
• "Past Error — Open Circuit —"
• "Past Error — Short Circuit —"
NOTE:
When the root cause appears to be a branch line or short circuit, be sure to check the control unit as well as
the communication line.
Present Error — Open Circuit —
Identify the error circuit using information from the “SELECT SYSTEM” and “CAN DIAG SUPPORT MNTR”
screens.
1. SELECT SYSTEM: Check the items indicated in “SELECT SYSTEM”. Draw a line on the diagnosis sheet
to indicate the error circuit.
NOTE:
CAN communication line has no error if units other than Diag on CAN units are indicated. An error may be
on the power supply of the control unit, DDL1 line or DDL2 line.
a. “TRANSMISSION” which is Diag on CAN unit, is not indicated on “SELECT SYSTEM” screen. This indi-
cates that DLC is not receiving a signal from TCM. Draw a line to indicate an error between DLC and TCM
(line 1-a in the figure).
NOTE:
• Diag on CAN units are not indicated on the “SELECT SYSTEM” screen when the CAN line between
Diag on CAN unit and the data link connector is open.
SKIB8891E

LAN-22
< SERVICE INFORMATION >[CAN FUNDAMENTAL]
TROUBLE DIAGNOSES WORK FLOW
• For a description of Diag on CAN, refer to LAN-5, "Diag on CAN".
2. CAN DIAG SUPPORT MNTR: Check each item on “CAN DIAG SUPPORT MNTR”. Draw a line on the
diagnosis sheet to indicate the error circuit.
a. Reception item of “ENGINE”: On “TCM”, “UNKWN” is indicated. This means ECM cannot receive the sig-
nal from TCM. Draw a line to indicate an error between ECM and TCM (line 2-a in the figure).
NOTE:
If “UNKWN” is indicated on “TRANSMIT DIAG”, then the control unit cannot transmit CAN communication
signal to each unit. Draw a line between the control unit and the splice.
b. Reception item of “ADAPTIVE LIGHT”: On “TCM”, “UNKWN” is indicated. This means AFS cannot
receive the signal from TCM. Draw a line to indicate an error between AFS and TCM (line 2-b in the fig-
ure).
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TROUBLE DIAGNOSES WORK FLOW
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c. Reception item of “MULTI AV”: “UNKWN” is not indicated. This indicates normal communication between
AV and its receiving units. Do not draw any line.
d. Reception item of “BCM”: On “TCM”, “UNKWN” is indicated. This means BCM cannot receive the signal
from TCM. Draw a line to indicate an error between BCM and TCM (line 2-d in the figure).
e. Reception item of “EPS” and “INTELLIGENT KEY”: “UNKWN” is not indicated. This indicates normal com-
munication between EPS and I-KEY and their receiving units. Do not draw any line.
NOTE:
SKIB8725E

LAN-24
< SERVICE INFORMATION >[CAN FUNDAMENTAL]
TROUBLE DIAGNOSES WORK FLOW
On CAN DIAG SUPPORT MNTR (without PAST), “UNKWN” is indicated even though the item is not used
in the trouble diagnosis. For the details of each item on CAN diagnostic support monitor, refer to LAN-40,
"CAN Diagnostic Support Monitor".
f. Reception item of “METER”: On “TCM”, “UNKWN” is indicated. This means M&A cannot receive the sig-
nal from TCM. Draw a line to indicate an error between M&A and TCM (line 2-f in the figure).
g. Reception item of “AUTO DRIVE POS.”: On “TCM”, “UNKWN” is indicated. This means ADP cannot
receive the signal from TCM. Draw a line to indicate an error between ADP and TCM (line 2-g in the fig-
ure).
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TROUBLE DIAGNOSES WORK FLOW
LAN-25
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h. Reception item of “ABS”: “UNKWN” is not indicated. This indicates normal communication between ABS
and its receiving units. Do not draw any line.
i. Reception item of “IPDM E/R”: “UNKWN” is not indicated. This indicates normal communication between
IPDM-E and its receiving units. Do not draw any line.
3. Based on information received from “CAN DIAG SUPPORT MNTR”, place a check mark on the known
good CAN communication line between ECM and IPDM-E.
a. Through the previous procedure, the circuit between ADP splice and TCM has the most amount of lines
(shade 3-a in the figure).
b. Place a check mark on the known good lines to establish the error circuit.
SKIB8727E

LAN-26
< SERVICE INFORMATION >[CAN FUNDAMENTAL]
TROUBLE DIAGNOSES WORK FLOW
Reception item of “IPDM E/R”: On “ECM”, “OK” is indicated. IPDM-E communicates normally with ECM.
Put a check mark on the normal circuit between ECM and IPDM-E (check mark 3-b in the figure).
4. Through the above procedure, the error is detected in the TCM branch line (shaded in the figure).
NOTE:
For abbreviations, refer to LAN-37, "
Abbreviation List".
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TROUBLE DIAGNOSES WORK FLOW
LAN-27
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5. Perform the inspection for the detected error circuit. For the inspection procedure, refer to LAN-61, "Mal-
function Area Chart".
Present Error — Short Circuit —
When the symptoms listed below exist, a short circuit of the CAN communication line is a possible cause.
Received data
Error symptom• Most the units connected to the CAN communication system go into fail-safe mode or are deactivated.
Inspection procedure
SKIB8893E
Item (CONSULT-II) Indication
SELECT SYSTEM All Diag on CAN units are not indicated.
CAN DIAG SUPPORT MNTR “UNKWN” is indicated under “TRANSMIT DIAG” and most reception items.

LAN-28
< SERVICE INFORMATION >[CAN FUNDAMENTAL]
TROUBLE DIAGNOSES WORK FLOW
• Refer to LAN-61, "Malfunction Area Chart".
Past Error — Open Circuit —
Review CAN communication signal chart based on information received from the interview with the customer
and on past error information from SELF-DIAG RESULTS and CAN DIAG SUPPORT MNTR.
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TROUBLE DIAGNOSES WORK FLOW
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1. SELF-DIAG RESULTS: Inspect the control units indicating “U1000” or “U1001” on SELF-DIAG RESULTS.
2. CAN DIAG SUPPORT MNTR (with PAST): Check the CAN DIAG SUPPORT MNTR (with PAST) of units
indicating “U1000” or “U1001” on SELF-DIAG RESULTS. Draw a line on the diagnosis sheet to indicate
the possible error circuit.
NOTE:
For the details of each indication on CAN DIAG SUPPORT MNTR, refer to LAN-40, "
CAN Diagnostic Sup-
port Monitor".
a. Reception item of “ENGINE”: “VDC/TCS/ABS”, “3” is indicated in the “PAST”. This means ECM could not
receive the signal from ABS in the past. Draw a line between ECM and ABS (line 2-a in the figure).
SKIB8731E