2004 INFINITI QX56 Can communication

AT-136
DTC P1721 VEHICLE SPEED SENSOR MTR
Revision: August 20072004 QX56
DTC P1721 VEHICLE SPEED SENSOR MTRPFP:24814
DescriptionUCS002FI
The vehicle speed sensor·MTR signal is transmitted from combination meter to TCM by CAN communication
line. The signal functions as an auxiliary device to the revolution sensor when it is malfunctioning. The TCM
will then use the vehicle speed sensor·MTR signal.
CONSULT-II Reference ValueUCS002FJ
On Board Diagnosis LogicUCS002FK

This is not an OBD-II self-diagnostic item.

Diagnostic trouble code “VHE SPD SE·MTR” with CONSULT-II is detected when TCM does not receive
the proper vehicle speed sensor MTR signal (input by CAN communication) from combination meter.
Possible CauseUCS002FL
Harness or connectors
(The sensor circuit is open or shorted.)
DTC Confirmation ProcedureUCS002FM
CAUTION:
Always drive vehicle at a safe speed.
NOTE:
If “DTC Confirmation Procedure” has been previously performed, always turn ignition switch “OFF”
and wait at least 10 seconds before performing the next test.
After the repair, perform the following procedure to confirm the malfunction is eliminated.
WITH CONSULT-II
1. Turn ignition switch “ON”. (Do not start engine.)
2. Select “DATA MONITOR” mode for “A/T” with CONSULT-II.
3. Start engine and maintain the following conditions for at least 5
consecutive seconds.
ACCELE POS: 1/8 or less
VHCL SPEED SE: 30 km/h (17 MPH) or more
4. If DTC is detected, go to AT-137, "
Diagnostic Procedure" .
Item name Condition Display value (Approx.) (km/h)
VHCL/S SE·MTR During driving Approximately matches the speedometer reading.
BCIA0030E

DTC P1721 VEHICLE SPEED SENSOR MTR
AT-137
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Diagnostic ProcedureUCS002FN
1. CHECK CAN COMMUNICATION LINE
Perform the self-diagnosis. Refer AT-93, "
SELF-DIAGNOSTIC RESULT MODE" .
Is a malfunction in the CAN communication indicated in the results?
YES >> Check CAN communication line. Refer to AT- 1 0 3 , "DTC U1000 CAN COMMUNICATION LINE" .
NO >> GO TO 2.
2. CHECK INPUT SIGNAL
With CONSULT-II
1. Start engine.
2. Select “ECU INPUT SIGNALS” in “DATA MONITOR” mode for
“A/T” with CONSULT-II.
3. Drive vehicle and read out the value of “VHCL/S SE·MTR”.
OK or NG
OK >> GO TO 4.
NG >> GO TO 3.
3. CHECK COMBINATION METER
Check combination meter. Refer to DI-17, "
How to Proceed With Trouble Diagnosis"
OK or NG
OK >> GO TO 8.
NG >> Repair or replace damaged parts.
4. CHECK TCM
Perform TCM input/output signals inspection. Refer to AT-90, "
TCM Input/Output Signal Reference Values" .
OK or NG
OK >> GO TO 5.
NG >> GO TO 7.
5. CHECK DTC
Perform “DTC Confirmation Procedure”.

Refer to AT- 1 3 6 , "DTC Confirmation Procedure" .
OK or NG
OK >>INSPECTION END
NG >> GO TO 6.
6. DETECT MALFUNCTIONING ITEM
Check the following items:

The A/T assembly harness connector terminals for damage or loose connection with harness connector.
OK or NG
OK >> Replace the control valve with TCM. Refer to AT - 2 4 1 , "Control Valve With TCM and A/T Fluid
Temperature Sensor 2" .
NG >> Repair or replace damaged parts.
Item name Condition Display value (km/h)
VHCL/S SE·MTR During driving Approximately matches the
speedometer reading.
SCIA2148E

CLOSED THROTTLE POSITION AND WIDE OPEN THROTTLE POSITION CIR-
CUIT
AT-187
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Revision: August 20072004 QX56
CLOSED THROTTLE POSITION AND WIDE OPEN THROTTLE POSITION CIR-
CUIT
PFP:18002
CONSULT-II Reference ValueUCS002IC
Diagnostic ProcedureUCS002ID
1. CHECK CAN COMMUNICATION LINE
Perform the self-diagnosis. Refer to AT - 9 3 , "
SELF-DIAGNOSTIC RESULT MODE" .
Is a malfunction in the CAN communication indicated in the results?
YES >> Check CAN communication line. Refer to AT- 1 0 3 , "DTC U1000 CAN COMMUNICATION LINE" .
NO >> GO TO 2.
2. CHECK THROTTLE POSITION SIGNAL CIRCUIT
With CONSULT-II
1. Turn ignition switch “ON”. (Do not start engine.)
2. Select “ECU INPUT SIGNALS” in “DATA MONITOR” mode for
“A/T” with CONSULT-II.
3. Depress accelerator pedal and read out the value of “CLSD THL
POS” and “W/O THL POS”.
OK or NG
OK >>INSPECTION END
NG >> Check the following items. If NG, repair or replace damaged parts.

Perform the self-diagnosis for “ENGINE” with CONSULT-II.

Open circuit or short to ground or short to power in harness or connectors.

Pin terminals for damage or loose connection with harness connector.
Item name Condition Display value
CLSD THL POSReleased accelerator pedal. ON
Fully depressed accelerator pedal. OFF
W/O THL POSFully depressed accelerator pedal. ON
Released accelerator pedal. OFF
Accelerator Pedal OperationMonitor Item
CLSD THL POS W/O THL POS
Released ON OFF
Fully depressed OFF ON
PCIA0070E

AT-188
BRAKE SIGNAL CIRCUIT
Revision: August 20072004 QX56
BRAKE SIGNAL CIRCUITPFP:25320
CONSULT-II Reference ValueUCS002IE
Diagnostic ProcedureUCS002IF
1. CHECK CAN COMMUNICATION LINE
Perform the self-diagnosis. Refer to AT-93, "
SELF-DIAGNOSTIC RESULT MODE" .
Is a malfunction in the CAN communication indicated in the results?
YES >> Check CAN communication line. Refer to AT-103, "DTC U1000 CAN COMMUNICATION LINE" .
NO >> GO TO 2.
2. CHECK STOP LAMP SWITCH CIRCUIT
With CONSULT-II
1. Turn ignition switch “ON”. (Do not start engine.)
2. Select “ECU INPUT SIGNALS” in “DATA MONITOR” mode for
“A/T” with CONSULT-II.
3. Read out ON/OFF switching action of the “BRAKE SW”.
OK or NG
OK >>INSPECTION END
NG >> GO TO 3.
3. CHECK STOP LAMP SWITCH
Check continuity between stop lamp switch harness connector termi-
nals 3 and 4.
Check stop lamp switch after adjusting brake pedal — refer to
BR-6, "
BRAKE PEDAL" .
OK or NG
OK >>INSPECTION END
NG >> Check the following items. If NG, repair or replace dam-
aged parts.

Harness for short or open between battery and stop lamp switch.

Harness for short or open between stop lamp switch and combination meter.
Item name Condition Display value
BRAKE SWDepressed brake pedal. ON
Released brake pedal. OFF
PCIA0070E
Condition Continuity
When brake pedal is depressed Yes
When brake pedal is released No
SCIA2126E

TOW MODE SWITCH
AT-189
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Revision: August 20072004 QX56
TOW MODE SWITCHPFP:25129
DescriptionUCS002IG
When tow mode switch is “ON”, tow mode switch signals are sent to TCM from combination meter by CAN
communication line.Then it`s a tow mode condition.
Diagnostic ProcedureUCS002IH
1. CHECK CAN COMMUNICATION LINE
Perform the self-diagnosis. Refer to AT - 9 3 , "
SELF-DIAGNOSTIC RESULT MODE" .
Is any malfunction in the CAN communication indicated in the results?
YES >> Check CAN communication line. Refer to AT- 1 0 3 , "DTC U1000 CAN COMMUNICATION LINE" .
NO >> GO TO 2.
2. CHECK POWER SOURCE
1. Turn ignition switch “ON”. (Do not start engine.)
2. Check the voltage between tow mode switch connector terminal
1 and ground.
OK or NG
OK >>INSPECTION END
NG >> GO TO 3.
3. CHECK TOW MODE SWITCH
1. Turn ignition switch “OFF”.
2. Disconnect tow mode switch connector.
3. Check continuity between tow mode switch connector M254 ter-
minals 1 and 2.
OK or NG
OK >> GO TO 4.
NG >> Repair or replace tow mode switch.
4. DETECT MALFUNCTIONING ITEM
Check the following items. If any items are damaged, repair or replace damaged parts.

Harness for short or open between combination meter connector terminal 35 and tow mode switch con-
nector terminal 1.

Harness for short or open between tow mode switch connector terminal 2 and ground.
OK or NG
OK >> GO TO 5.
NG >> Repair or replace damaged parts.
ConditionTo w m o d e
switchData (Approx.)
When ignition switch is turned to “ON”ON 0V
OFF Battery voltage
SCIA5156E
Condition Continuity
To w m o d e s w i t c h “ O N ” Ye s
To w m o d e s w i t c h “ O F F ” N o
SCIA5157E

TROUBLE DIAGNOSIS FOR SYMPTOMS
AT-191
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Revision: August 20072004 QX56
TROUBLE DIAGNOSIS FOR SYMPTOMSPFP:00007
AT CHECK Indicator Lamp Does Not Come OnUCS002II
SYMPTOM:
AT CHECK indicator lamp does not come on for about 2 seconds when turning ignition switch to
“ON”.
DIAGNOSTIC PROCEDURE
1. CHECK CAN COMMUNICATION LINE
Perform the self-diagnosis. Refer to AT - 9 3 , "
SELF-DIAGNOSTIC RESULT MODE" .
Is any malfunction in the CAN communication indicated in the results?
YES >> Check CAN communication line. Refer to AT- 1 0 3 , "DTC U1000 CAN COMMUNICATION LINE" .
NO >> GO TO 2.
2. CHECK TCM POWER SOURCE
1. Disconnect A/T assembly harness connector.
2. Turn ignition switch “ON”. (Do not start engine.)
3. Check voltage between A/T assembly harness connector (vehi-
cle side) and ground. Refer to AT- 5 2 , "
Wiring Diagram — AT —"
.
4. Turn ignition switch “OFF”.
5. Check voltage between A/T assembly harness connector (vehi-
cle side) and ground. Refer to AT- 5 2 , "
Wiring Diagram — AT —"
.
OK or NG
OK >> GO TO 4.
NG >> GO TO 3.
3. DETECT MALFUNCTIONING ITEM
Check the following items:

Harness for short or open between battery and A/T assembly harnhess connector terminals 1, 2

Harness for short or open between ignition switch and TCM connector terminal 6

10A fuse (No. 3, located in the fuse block)

10A fuse (No. 49, located in the IPDM E/R)

Ignition switch, Refer to PG-4, "POWER SUPPLY ROUTING CIRCUIT" .
OK or NG
OK >> GO TO 4.
NG >> Repair or replace damaged parts.
Item Connector No.Te r m i n a l N o .
(Wire color)Vo ltag e
TCM F91 (P) - Ground
Battery voltage 2 (P) - Ground
6 (Y/R) - Ground
SCIA2105E
Item Connector No.Te r m i n a l N o .
(Wire color)Voltage
TCM F91 (P) - Ground
Battery voltage
2 (P) - Ground
6 (Y/R) - Ground 0V
SCIA2104E

TROUBLE DIAGNOSIS FOR SYMPTOMS
AT-195
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Revision: August 20072004 QX56
5. CHECK SYMPTOM
Check again. Refer to AT- 6 2 , "
Check at Idle" .
OK or NG
OK >>INSPECTION END
NG >> GO TO 6.
6. PERFORM TCM INSPECTION
1. Perform TCM input/output signals inspection. Refer to AT-90, "
TCM Input/Output Signal Reference Val-
ues" .
2. If NG, recheck A/T assembly harness connector terminals for damage or loose connection with harness
connector.
OK or NG
OK >>INSPECTION END
NG >> Repair or replace damaged parts.
Large Shock (“N” to “D” Position)UCS002IM
SYMPTOM:
A noticeable shock occurs when the selector lever is shifted from the “N” to “D” position.
DIAGNOSTIC PROCEDURE
1. CHECK SELF-DIAGNOSTIC RESULTS
Perform self-diagnosis. Refer to AT- 9 3 , "
SELF-DIAGNOSTIC RESULT MODE" .
Do the self-diagnostic results indicate A/T fluid temperature sensor, engine speed signal, accelerator pedal
position sensor, ATF pressure switch 1, front brake solenoid valve, CAN communication line?
YES >> Check the malfunctioning system. Refer to AT-131, "DTC P1710 A/T FLUID TEMPERATURE
SENSOR CIRCUIT" , AT-115, "DTC P0725 ENGINE SPEED SIGNAL" ., AT- 1 2 9 , "DTC P1705
THROTTLE POSITION SENSOR" , AT-175, "DTC P1841 ATF PRESSURE SWITCH 1" , AT-
151, "DTC P1757 FRONT BRAKE SOLENOID VALVE" , AT- 1 0 3 , "DTC U1000 CAN COMMUNI-
CATION LINE" .
NO >> GO TO 2.
2. ENGINE IDLE SPEED
Check the engine idle speed. Refer to EC-32, "
Idle Speed and Ignition Timing Check" .
OK or NG
OK >> GO TO 3.
NG >> Repair.
3. CHECK CONTROL CABLE
Check the control cable.

Refer to AT- 2 3 4 , "Checking of A/T Position" .
OK or NG
OK >> GO TO 4.
NG >> Adjust control cable. Refer to AT-234, "
Adjustment of A/
T Position" .
LCIA0324E

AT-198
TROUBLE DIAGNOSIS FOR SYMPTOMS
Revision: August 20072004 QX56
Vehicle Does Not Creep Backward In “R” PositionUCS002IN
SYMPTOM:
The vehicle does not creep in the “R” position. Or an extreme lack of acceleration is observed.
DIAGNOSTIC PROCEDURE
1. CHECK SELF-DIAGNOSTIC RESULTS
Perform self-diagnosis. Refer to AT- 9 3 , "
SELF-DIAGNOSTIC RESULT MODE" .
Do the self-diagnostic results indicate accelerator pedal position sensor, ATF pressure switch 6, high and low
reverse clutch solenoid valve, CAN communication line, PNP switch?
YES >> Check the malfunctioning system. Refer to AT - 1 2 9 , "DTC P1705 THROTTLE POSITION SEN-
SOR" , AT - 1 8 4 , "DTC P1846 ATF PRESSURE SWITCH 6" , AT-163, "DTC P1767 HIGH AND
LOW REVERSE CLUTCH SOLENOID VALVE" , AT-103, "DTC U1000 CAN COMMUNICATION
LINE" , AT-109, "DTC P0705 PARK/NEUTRAL POSITION SWITCH" .
NO >> GO TO 2.
2. CHECK CONTROL CABLE
Check the control cable.

Refer to AT-234, "Checking of A/T Position" .
OK or NG
OK >> GO TO 3.
NG >> Adjust control cable. Refer to AT-234, "
Adjustment of A/
T Position" .
3. CHECK A/T FLUID LEVEL
Check A/T fluid level. Refer to AT-13, "
Checking A/T Fluid" .
OK or NG
OK >> GO TO 4.
NG >> Refill ATF.
4. CHECK STALL TEST
Check stall revolution with selector lever in “1” and “R” positions.
Refer to AT-58, "
STALL TEST" .
OK or NG
OK >> GO TO 6.
OK in “1” position, NG in “R” position>>GO TO 5.
NG in both “1” and “R” positions>>GO TO 8.
LCIA0324E
SAT6 3 8A
SAT4 9 3G