2009 INFINITI QX56 sensor

DIAGNOSIS AND REPAIR WORKFLOWTM-5
< BASIC INSPECTION >
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BASIC INSPECTION
DIAGNOSIS AND REPAIR WORKFLOW
Work FlowINFOID:0000000003771803
INTRODUCTION
The TCM receives a signal from the output speed sensor, accelera-
tor pedal position sensor (throttle position sensor) or transmission
range switch. Then provides shift c ontrol or lock-up control via A/T
solenoid valves.
The TCM also communicates with the ECM by means of a signal
sent from sensing elements used wit h the OBD-related parts of the
A/T system for malfunction-diagnostic purposes. The TCM is capa-
ble of diagnosing malfunctioning parts while the ECM can store mal-
functions in its memory.
Input and output signals must always be correct and stable in the
operation of the A/T system. T he A/T system must be in good oper-
ating condition and be free of valve seizure, solenoid valve malfunc-
tion, etc.
It is much more difficult to diagnose an error that occurs intermit-
tently rather than continuously. Most intermittent errors are caused
by poor electric connections or impr oper wiring. In this case, careful
checking of suspected circuits may help prevent the replacement of
good parts.
A visual check only may not find t he cause of the errors. A road test
with CONSULT-III (or GST) or a circuit tester connected should be
performed. Follow the “DETAILED 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 errors, especially
intermittent ones. Find out what symptoms are present and under
what conditions they occur. A “Diagnostic work sheet” as shown on
the example (Refer to TM-6
) should be used.
Start your diagnosis by looking for “conventional” errors first. This will
help troubleshoot driveability errors on an electronically controlled
engine vehicle.
Also check related Service bulletins.
DETAILED FLOW
1.COLLECT THE INFORMATION FROM THE CUSTOMER
Get the detailed information from the customer about the symptom (the condition and the environment when
the incident/malfunction occurred) using diagnosis worksheet. Refer to TM-6, "Diagnostic Work Sheet"
.
>> GO TO 2.
2.CHECK SYMPTOM 1
Check the following items based on the in formation obtained from the customer.
 Fail-safe. Refer to TM-115, "Fail-Safe"
.
 A/T fluid inspection. Refer to TM-179, "Checking the A/T Fluid (ATF)"
.
 Stall test. Refer to TM-186, "Inspection and Judgment"
.
 Line pressure test. Refer to TM-188, "Inspection and Judgment"
.
SAT631IB
SAT632I
SEF234G
Revision: December 20092009 QX56

TM-20
< FUNCTION DIAGNOSIS >
A/T CONTROL SYSTEM
TCM Function
INFOID:0000000003771808
The function of the TCM is to:
 Receive input signals sent from various switches and sensors.
 Determine required line pressure, shifting poi nt, lock-up operation, and engine brake operation.
 Send required output signals to the respective solenoids.
CONTROL SYSTEM OUTLINE
The automatic transmission senses v ehicle operating conditions through vari ous sensors or signals. It always
controls the optimum shift position and reduces shifting and lock-up shocks.
1. Front brake 2. Input clutch 3. Direct clutch
4. High and low reverse clutch 5. Reverse brake 6. Forward brake
7. Low coast brake 8. 1st one-way clutch 9. Forward one-way clutch
10. 3rd one-way clutch 11. Front sun gear 12. Input shaft
13. Mid internal gear 14. Front internal gear 15. Rear carrier
16. Rear sun gear 17. Mid sun gear 18. Front carrier
19. Mid carrier 20. Rear internal gear 21. Output shaft
22. Parking gear 23. Parking pawl
SCIA1519E
Revision: December 20092009 QX56

A/T CONTROL SYSTEMTM-21
< FUNCTION DIAGNOSIS >
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CONTROL SYSTEM DIAGRAM
CAN CommunicationINFOID:0000000003771809
SYSTEM DESCRIPTION
CAN (Controller Area Network) is a serial communication li ne for real time application. It is an on-vehicle mul-
tiplex communication line with high data communication speed and excellent error detection ability. Many elec-
tronic control units are equipped onto a vehicle, and each control unit shares information and links with other
control units during operation (not independent). In CAN communication, control units are connected with 2
communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring.
Each control unit transmits/receives data but selectively reads required data only. For details, refer to LAN-4,
"System Description".
SENSORS (or SIGNALS)
⇒TCM
⇒ACTUATORS
Transmission range switch
Accelerator pedal position sensor
Closed throttle position signal
Wide open throttle position signal
Engine speed signal
A/T fluid temperature sensor
Output speed sensor
Vehicle speed signal
Stop lamp switch signal
Input speed sensor
1st position switch signal
4th position switch signal
ATF pressure switch 2 signal
Tow mode switch signal Shift control
Line pressure control
Lock-up control
Engine brake control
Timing control
Fail-safe control
Self-diagnosis
CONSULT-III co
mmunication
line
Duet-EA control
CAN system Input clutch solenoid valve
Direct clutch solenoid valve
Front brake solenoid valve
High and low reverse clutch sole-
noid valve
Low coast brake solenoid valve
Torque converter clutch solenoid
valve
Line pressure solenoid valve
A/T CHECK indicator lamp
Starter relay
Back-up lamp relay
JSDIA1315GB
Revision: December 20092009 QX56

TM-22
< FUNCTION DIAGNOSIS >
A/T CONTROL SYSTEM
Input/Output Signal of TCM
INFOID:0000000003771810
*1: Spare for output speed sensor.
*2: Spare for accelerator pedal position signal
*3: If these input and output signals are different, the TCM triggers the fail-safe function.
*4: CAN comm unications
*5: Used as a condition for starting self-diagnostics; if self-diagnostics are not started, it is judged that there is some kin d of error.
*6: A/T fluid temperature sensor 2 does not have any function.
Line Pressure ControlINFOID:0000000003771811
 When an input torque signal equivalent to the engine drive force is sent from the ECM to the TCM, the TCM controls the line pressure solenoid.
Control item Line
pres- sure
control Vehicle
speed
control S h i f t
control Lock-up
control Engine
brake
control Fail-safe
function (*3) Self-diag-
nostics
function
Input Accelerator pedal position signal
(*4)XXXXX X X
Output speed sensor X X X X X X
Vehicle speed signal
(*1) (*4)XXXX X
Closed throttle position signal
(*4)(*2) X (*2) X X (*2) X (*5) X
Wide open throttle position signal
(*4)(*2) X (*2) X (*2) X (*5) X
Input speed sensor 1 X X X X X
Input speed sensor 2
(for 4th speed only) XX X X X
Engine speed signals
(*4)XX
Transmission range switch X X X X X X X
Stop lamp switch signal
(*4)XXX (*5) X
A/T fluid temperature sensors 1, 2 (*6) X X X X X X X
ASCD Operation signal
(*4)XXXX
Overdrive cancel sig-
nal
(*4)XXX
TCM power supply voltage signal X X X X X X
Output Direct clutch solenoid X X X X
Input clutch solenoid X X X X
High and low reverse clutch solenoid X X X X
Front brake solenoid X X X X
Low coast brake solenoid (ATF pressure
switch 2)
XX X X X
Line pressure solenoid X X X X X X X
TCC solenoid X X X
Starter relay XX
Revision: December 20092009 QX56

TM-24
< FUNCTION DIAGNOSIS >
A/T CONTROL SYSTEM
The necessary and adequate line pressure for shift change is set.
For this reason, line pressure pattern setting corresponds to input
torque and gearshift selection. Also, line pressure characteristic is
set according to engine speed, during engine brake operation.
At Low Fluid Temperature
When the A/T fluid temperature drops below the prescribed tempera-
ture, in order to speed up the action of each friction element, the line
pressure is set higher than the normal line pressure characteristic.
Shift ControlINFOID:0000000003771812
The clutch pressure control solenoid is controlled by the signals from the switches and sensors. Thus, the
clutch pressure is adjusted to be appropriate to the engine load state and vehicle driving state. It becomes
possible to finely control the clutch hydraulic pressu re with high precision and a smoother shift change charac-
teristic is attained.
SHIFT CHANGE
The clutch is controlled with the optimum timing and oil pressure by the engine speed, engine torque informa-
tion, etc.
Shift Change System Diagram
PCIA0010E
PCIA0011E
PCIA0012E
Revision: December 20092009 QX56

TM-30
< FUNCTION DIAGNOSIS >
ON BOARD DIAGNOSTIC (OBD) SYSTEM
ON BOARD DIAGNOSTIC (OBD) SYSTEM
IntroductionINFOID:0000000003771819
The A/T system has two self-diagnostic systems.
The first is the emission-related on board diagnostic syst em (OBD-II) performed by the TCM in combination
with the ECM. The malfunction is indicated by the MI L (malfunction indicator lamp) and is stored as a DTC in
the ECM memory but not the TCM memory.
The second is the TCM original self-diagnosis indicat ed by the A/T CHECK indicator lamp. The malfunction is
stored in the TCM memory. The detected items are ov erlapped with OBD-II self-diagnostic items. For detail,
refer to TM-32, "CONSULT-III Function (TRANSMISSION)"
.
OBD-II Function for A/T SystemINFOID:0000000003771820
The ECM provides emission-related on board diagnostic (O BD-II) functions for the A/T system. One function
is to receive a signal from the TCM used with OBD-relat ed parts of the A/T system. The signal is sent to the
ECM when a malfunction occurs in the corresponding OBD-related part. The other function is to indicate a
diagnostic result by means of the MIL (malfunction indi cator lamp) on the instrument panel. Sensors, switches
and solenoid valves are used as sensing elements.
The MIL automatically illuminates in One or Two Trip Detection Logic when a malfunction is sensed in relation
to A/T system parts.
One or Two Trip Detection Logic of OBD-IIINFOID:0000000003771821
ONE TRIP DETECTION LOGIC
If a malfunction is sensed during the first test drive, the MIL will illuminate and the malfunction will be stored in
the ECM memory as a DTC. The TCM is not provided with such a memory function.
TWO TRIP DETECTION LOGIC
When a malfunction is sensed during the first test drive, it is stored in the ECM memory as a 1st trip DTC
(diagnostic trouble code) or 1st trip freeze frame data. At this point, the MIL will not illuminate. — 1st Trip
If the same malfunction as that experienced during the fi rst test drive is sensed during the second test drive,
the MIL will illuminate. — 2nd Trip
The “Trip” in the “One or Two Trip Detection Logic” means a driving mode in which self-diagnosis is performed
during vehicle operation.
OBD-II Diagnostic Trouble Code (DTC)INFOID:0000000003771822
HOW TO READ DTC AND 1ST TRIP DTC
DTC and 1st trip DTC can be read by the following methods.
( with CONSULT-III or GST) CONSULT-III or GST (Generic Scan Tool) Examples: P0705, P0720 etc.
These DTC are prescribed by SAE J2012.
(CONSULT-III also displays the malfunctioning component or system.)
 1st trip DTC No. is the same as DTC No.
 Output of the diagnostic troubl e code indicates that the indicated circuit has a malfunction. How-
ever, in case of the Mode II and GST, they do not indicate whether the malfunction is still occurring or
occurred in the past and returned to normal.
CONSULT-III can identify them as shown below, therefore, CONSULT-III (if available) is recom-
mended.
Freeze Frame Data and 1st Trip Freeze Frame Data
The ECM has a memory function, which stores the driv ing condition such as fuel system status, calculated
load value, engine coolant temperature, short term f uel trim, long term fuel trim, engine speed and vehicle
speed at the moment the ECM detects a malfunction.
Data which are stored in the ECM memory, along with the 1st trip DTC, are called 1st trip freeze frame data,
and the data, stored together with the DTC data, are called freeze frame data and displayed on CONSULT-III
or GST. The 1st trip freeze frame data can only be disp layed on the CONSULT-III screen, not on the GST. For
detail, refer to TM-30
.
Only one set of freeze frame data (either 1st trip freez e frame data of freeze frame data) can be stored in the
ECM. 1st trip freeze frame data is stored in the ECM me mory along with the 1st trip DTC. There is no priority
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
Revision: December 20092009 QX56

TM-32
< FUNCTION DIAGNOSIS >
DIAGNOSIS SYSTEM (TCM)
DIAGNOSIS SYSTEM (TCM)
CONSULT-III Function (TRANSMISSION)INFOID:0000000004019470
CONSULT-III can display each diagnostic item using the diagnostic test modes shown following.
SELF-DIAGNOSTIC RESULT MODE
Display Items List
X: Applicable, —: Not applicable
TCM diagnostic mode Description
Work Support This mode enables a technician to adjust some devices faster and more accurately.
Self-Diagnostic Results Retrieve DTC from ECU and display diagnostic items.
Data Monitor Monitor the input/output signal of the control unit in real time.
CAN Diagnosis Support Monitor It monitors the status of CAN communication.
DTC & SRT Confirmation The status of system monitoring tests and the self-diagnosis status/result can be confirmed.
ECU Identification Display the ECU identification nu mber (part number etc.) of the selected system.
Items (CONSULT-III
screen terms) Malfunction is detected when... TCM self-di-
agnosis OBD (DTC)
Reference page
“TRANSMIS-
SION” with
CONSULT-III MIL indicator
lamp*1, “EN-
GINE” with
CONSULT-III or
GST
CAN COMM CIRCUIT  When a malfunction is detected in CAN communica-
tions U1000 U1000
TM-39
STARTER RELAY If this signal is ON other than in P or N position, this is
judged to be a malfunction.
(And if it is OFF in P or N position, this too is judged to
be a malfunction.) P0615 —
TM-40
TRANSMISSION
CONT TCM is malfunctioning. P0700 P0700
TM-43
T/M RANGE SWITCH A Transmission range switch 1-4 signals input with im-
possible pattern
 “P” position is detected from N position without any other position being detected in between. P0705 P0705
TM-44
INPUT SPEED SEN-
SOR A TCM does not receive the proper voltage signal from
the sensor.
 TCM detects an irregularity only at position of 4th gear for input speed sensor 2. P0717 P0717
TM-47
OUTPUT SPEED SEN-
SOR A Signal from vehicle speed sensor A/T (output speed
sensor) not input due to cut line or the like
 Unexpected signal input during running
 After ignition switch is turned ON, unexpected signal input from vehicle speed sensor MTR before the vehi-
cle starts moving P0720 P0720
TM-50
ENGINE SPEED TCM does not receive the CAN communication signal
from the ECM. P0725 —
TM-52
1GR INCORRECT RA-
TIO A/T cannot shift to 1st gear P0731 P0731
TM-55
2GR INCORRECT RA-
TIO A/T cannot shift to 2nd gear P0732 P0732
TM-57
3GR INCORRECT RA-
TIO A/T cannot shift to 3rd gear P0733 P0733
TM-59
Revision: December 20092009 QX56

DIAGNOSIS SYSTEM (TCM)TM-33
< FUNCTION DIAGNOSIS >
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4GR INCORRECT RA-
TIO  A/T cannot shift to 4th gear P0734 P0734
TM-61
5GR INCORRECT RA-
TIO A/T cannot shift to 5th gear P0735 P0735
TM-63
TORQUE CONVERT-
ER Normal voltage not applied to solenoid due to cut line,
short, or the like P0740 P0740
TM-64
TORQUE CONVERT-
ER A/T cannot perform lock-up even if electrical circuit is
good.
 TCM detects as irregular by comparing difference val-
ue with slip rotation. P0744 P0744*2
TM-67
PC SOLENOID Normal voltage not applied to solenoid due to cut line,
short, or the like
 TCM detects as irregular by comparing target value
with monitor value. P0745 P0745
TM-68
TP SENSOR TCM does not receive the proper accelerator pedal po-
sition signals (input by CAN communication) from
ECM. P1705 P1705
TM-70
TRANS FLUID TEMP
SEN During running, the ATF temperature sensor signal
voltage is excessively high or low P1710 P0710
TM-72
VEHICLE SPEED SIG-
NAL Signal (CAN communication) from vehicle speed sen-
sor MTR not input due to cut line or the like
 Unexpected signal input during running P1721 —
TM-74
INTERLOCK Except during shift change, the gear position and ATF
pressure switch states are monitored and comparative
judgement made. P1730 P1730
TM-76
1GR E/BRAKING Each ATF pressure switch and solenoid current is
monitored and if a pattern is detected having engine
braking 1st gear other than in the "1" position, a mal-
function is detected. P1731 —
TM-78
INPUT CLUTCH SOLE-
NOID Normal voltage not applied to solenoid due to function-
al malfunction, cut line, short, or the like
 TCM detects as irregular by comparing target value
with monitor value. P1752 P1752
TM-80
FR BRAKE SOLENOID Normal voltage not applied to solenoid due to function-
al malfunction, cut line, short, or the like
 TCM detects as irregular by comparing target value
with monitor value. P1757 P1757
TM-82
DRCT CLUTCH SOLE-
NOID Normal voltage not applied to solenoid due to cut line,
short, or the like
 TCM detects as irregular by comparing target value
with monitor value. P1762 P1762
TM-84
HLR CLUTCH SOLE-
NOID Normal voltage not applied to solenoid due to function-
al malfunction, cut line, short, or the like
 TCM detects as irregular by comparing target value
with monitor value. P1767 P1767
TM-86
L C BRAKE SOLENOID Normal voltage not applied to solenoid due to function-
al malfunction, cut line, short, or the like P1772 P1772
TM-88
Items (CONSULT-III
screen terms) Malfunction is detected when... TCM self-di-
agnosis OBD (DTC)
Reference page
“TRANSMIS-
SION” with
CONSULT-III MIL indicator
lamp*1, “EN-
GINE” with
CONSULT-III or
GST
Revision: December 20092009 QX56