TROUBLE DIAGNOSIS
CVT-25
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CVT
Step Motor
If an unexpected signal is sent from the step motor to the TCM, the step motor coil phases “A” through “D” are
all turned OFF to hold the gear ratio used right before the non-standard condition occurred.
CVT Lock-up Select Solenoid
If an unexpected signal is sent from the solenoid to the TCM, the CVT lock-up select solenoid is turned OFF to
cancel the lock-up.
TCM Power Supply (Memory Back-up)
Transaxle assembly is protected by limiting the engine torque when the memory back-up power supply (for
controlling) from the battery is not supplied to TCM. Normal statues is restored when turning the ignition switch
OFF to ON after the normal power supply.
How to Perform Trouble Diagnosis for Quick and Accurate RepairBCS001GG
INTRODUCTION
The TCM receives a signal from the vehicle speed sensor, PNP
switch and provides shift control or lock-up control via CVT solenoid
valves.
Input and output signals must always be correct and stable in the
operation of the CVT system. The CVT system must be in good
operating condition and be free of valve seizure, solenoid valve mal-
function, 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 improper wiring. In this case, careful
checking of suspected circuits may help prevent the replacement of
good parts.
A visual check only may not find the cause of the errors. A road test
with CONSULT-II or a circuit tester connected should be performed.
Follow the CVT-26, "
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 errors, especially
intermittent ones. Find out what symptoms are present and under
what conditions they occur. A “DIAGNOSTIC WORKSHEET” as
shown on the example (Refer to CVT-27
) 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.
SAT631IB
SAT632I
SEF234G
DTC P1777 STEP MOTOR - CIRCUIT
CVT-153
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CVT
DTC P1777 STEP MOTOR - CIRCUITPFP:31020
DescriptionBCS001LS
The step motor changes the step with turning 4 coils ON/OFF according to the signal from TCM. As a result,
the flow of line pressure to primary pulley is changed and pulley ratio is controlled.
CONSULT-II Reference ValueBCS001LT
Remarks: Specification data are reference values.
On Board Diagnosis LogicBCS001LU
Diagnostic trouble code “P1777 STEP MOTR CIRC” with CONSULT-II is detected under the following condi-
tions.
When operating step motor ON and OFF, there is no proper change in the voltage of TCM terminal which
corresponds to it.
Possible CauseBCS001LV
Step motor
Harness or connectors
(Step motor circuit is open or shorted.)
DTC Confirmation ProcedureBCS001LW
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, touch “ERASE” on “SELF-DIAG RESULTS” and then perform the following procedure to con-
firm the malfunction is eliminated.
WITH CONSULT-II
1. Turn ignition switch ON and select “DATA MONITOR” mode for
“TRANSMISSION” with CONSULT-II.
2. Drive vehicle for at least 5 consecutive seconds.
3. If DTC is detected, go to CVT-155, "
Diagnostic Procedure" .
Item name Condition Display value (Approx.)
STM STEP
During driving−20 step - 190 step
SMCOIL A
Changes ON⇔OFF SMCOIL B
SMCOIL C
SMCOIL D
BCIA0031E
DTC P1777 STEP MOTOR - CIRCUIT
CVT-155
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CVT
TCM terminals data are reference values.
Diagnostic ProcedureBCS001LY
1. CHECK INPUT SIGNAL
With CONSULT-II
1. Start engine.
2. Select “SELECTION FROM MENU” in “DATA MONITOR” mode
for “TRANSMISSION” with CONSULT-II.
3. Start vehicle and read out the value of “STM STEP”, “SMCOIL
A”, “SMCOIL B”, “SMCOIL C”, and “SMCOIL D”.
OK or NG
OK >> GO TO 4.
NG >> GO TO 2.
2. CHECK HARNESS BETWEEN TCM AND STEP MOTOR
1. Turn ignition switch OFF.
2. Disconnect CVT unit connector and TCM connector.
3. Check continuity between TCM connector terminals and CVT
unit harness connector terminals.
4. If OK, check harness for short to ground and short to power.
5. If OK, check continuity between body ground and CVT assembly.
6. Reinstall any part removed.
OK or NG
OK >> GO TO 3.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
Terminal Wire color Item Condition Data (Approx.)
11 G/R Step motor A Within 2 seconds after ignition switch ON, the time measure-
ment by using the pulse width measurement function (Hi level) of
CONSULT-II.*1
CAUTION:
Connect the diagnosis data link cable to the vehicle diagno-
sis connector.
*1: A circuit tester cannot be used to test this item.30.0 msec
12 O/B Step motor B10.0 msec
20 R Step motor C30.0 msec
21 R/G Step motor D10.0 msec
Item name Condition Display value (Approx.)
STM STEP
During driving−20 step - 190 step
SMCOIL A
Changes ON⇔OFF SMCOIL B
SMCOIL C
SMCOIL D
SCIA4516E
Item Connector Terminal Continuity
TCM F106 11
Ye s
CVT unit harness connector F49 6
TCM F106 12
Ye s
CVT unit harness connector F49 7
TCM F106 20
Ye s
CVT unit harness connector F49 8
TCM F106 21
Ye s
CVT unit harness connector F49 9
SCIA4695E
BASIC SERVICE PROCEDURE
EC-45
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EC
17. DETECT MALFUNCTIONING PART
Check the following.
Check camshaft position sensor (PHASE) and circuit. Refer to EC-176 .
Check crankshaft position sensor (POS) and circuit. Refer to EC-169 .
OK or NG
OK >> GO TO 18.
NG >> 1. Repair or replace.
2. GO TO 4.
18. CHECK ECM FUNCTION
1. Substitute another known-good ECM to check ECM function. (ECM may be the cause of an incident, but
this is a rare case.)
2. Perform initialization of NATS system and registration of all NATS ignition key IDs. Refer to BL-139,
"NATS(Nissan Anti-Theft System)" .
>> GO TO 4.
Idle Speed and Ignition Timing CheckBBS005BU
IDLE SPEED
With CONSULT-II
Check idle speed in “DATA MONITOR” mode with CONSULT-II.
Without CONSULT-II
Check the idle speed by installing the pulse type tachometer clamp on the loop wire or on suitable high-tension
wire which installed between No.1 ignition coil and No.1 spark plug.
NOTE:
For the method of installing the tachometer, refer to EC-45, "
IGNITION TIMING" .
IGNITION TIMING
Any of following two methods may be used.
Method A
1. Slide the harness protector of ignition coil No.1 to clear the
wires.
2. Attach timing light to the wire as shown in the figure.
SEF058Y
PBIB2137E
EC-46
[QR]
BASIC SERVICE PROCEDURE
3. Check ignition timing.
Method B
1. Remove ignition coil No. 1.
2. Connect No. 1 ignition coil and No. 1 spark plug with suitable
high-tension wire as shown, and attach timing light clamp to this
wire.
PBIB2177E
PBIB2132E
PBIB2138E
SEF166Y
EC-86
[QR]
TROUBLE DIAGNOSIS
DATA MONITOR (SPEC) MODE
Monitored Item
NOTE:
Any monitored item that does not match the vehicle being diagnosed is deleted from the display automatically.
ACTIVE TEST MODE
Test Item
Monitored item [Unit]ECM
INPUT
SIGNALSMAIN
SIGNALSDescription Remarks
ENG SPEED [rpm]×
Indicates the engine speed computed
from the signals of the crankshaft posi-
tion sensor (POS) and camshaft position
sensor (PHASE).
MAS A/F SE-B1 [V]××
The signal voltage of the mass air flow
sensor specification is displayed.When engine is running specification
range is indicated.
B/FUEL SCHDL
[msec]
“Base fuel schedule” indicates the fuel
injection pulse width programmed into
ECM, prior to any learned on board cor-
rection.
When engine is running specification
range is indicated.
A/F ALPHA-B1 [%]×
The mean value of the air-fuel ratio feed-
back correction factor per cycle is indi-
cated.When engine is running specification
range is indicated.
This data also includes the data for the
air-fuel ratio learning control.
TEST ITEM CONDITION JUDGEMENT CHECK ITEM (REMEDY)
FUEL INJEC-
TION
Engine: Return to the original
trouble condition
Change the amount of fuel injec-
tion using CONSULT-II.If trouble symptom disappears, see
CHECK ITEM.
Harness and connectors
Fuel injector
Heated oxygen sensor 1
IGNITION TIM-
ING
Engine: Return to the original
trouble condition
Timing light: Set
Retard the ignition timing using
CONSULT-II.If trouble symptom disappears, see
CHECK ITEM.
Perform Idle Air Volume Learning.
POWER BAL-
ANCE
Engine: After warming up, idle
the engine.
Air conditioner switch OFF
Shift lever: P or N
Cut off each fuel injector signal
one at a time using CONSULT-II.Engine runs rough or dies.
Harness and connectors
Compression
Fuel injector
Power transistor
Spark plug
Ignition coil
COOLING FAN*
Ignition switch: ON
Turn the cooling fan LOW, MID,
HI, OFF with CONSULT-II.Cooling fan moves and stops.
Harness and connectors
Cooling fan motor
IPDM E/R
ENG COOLANT
TEMP
Engine: Return to the original
trouble condition
Change the engine coolant tem-
perature using CONSULT-II.If trouble symptom disappears, see
CHECK ITEM.
Harness and connectors
Engine coolant temperature sen-
sor
Fuel injector
FUEL PUMP
RELAY
Ignition switch: ON (Engine
stopped)
Turn the fuel pump relay ON and
OFF using CONSULT-II and lis-
ten to operating sound.Fuel pump relay makes the operat-
ing sound.Harness and connectors
Fuel pump relay
EC-100
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TROUBLE DIAGNOSIS - SPECIFICATION VALUE
10. DETECT MALFUNCTIONING PART
1. Check the following.
–Ignition coil and its circuit (Refer to EC-329, "IGNITION SIGNAL" .)
–Fuel injector and its circuit (Refer to EC-289, "FUEL INJECTOR" .)
–Intake air leakage
–Low compression pressure (Refer to EM-65, "CHECKING COMPRESSION PRESSURE" .)
2. If NG, repair or replace the malfunctioning part.
If OK, replace fuel injector. (It may be caused by leakage from fuel injector or clogging.)
>> GO TO 11.
11 . CHECK “A/F ALPHA-B1”
1. Start engine.
2. Select “A/F ALPHA-B1” in “DATA MONITOR (SPEC)” mode, and make sure that the each indication is
within the SP value.
OK or NG
OK >>INSPECTION END
NG >> GO TO 12.
12. CHECK HEATED OXYGEN SENSOR 1 FUNCTION
1. Run engine at about 2,000 rpm for about 2 minutes under no load.
2. Select “HO2S1 MNTR (B1)”, in “DATA MONITOR” mode.
3. Running engine at 2,000 rpm under no load (The engine is
warmed up to normal operating temperature.), check that the
monitor fluctuates between LEAN and RICH more than 5 times
during 10 seconds.
OK or NG
OK >> GO TO 15.
NG >> GO TO 13.
13. CHECK HEATED OXYGEN SENSOR 1 CIRCUIT
Check heated oxygen sensor 1 and its circuit. (Refer to EC-143, "
DTC P0132 HO2S1" .)
>> GO TO 14.
14. CHECK “A/F ALPHA-B1”
1. Start engine.
2. Select “A/F ALPHA-B1” in “DATA MONITOR (SPEC)” mode, and make sure that the each indication is
within the SP value.
OK or NG
OK >>INSPECTION END
NG >> GO TO 15.1 time : RICH → LEAN → RICH
2 times : RICH → LEAN → RICH → LEAN → RICH
SEF820Y
IGNITION SIGNAL
EC-329
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EC
IGNITION SIGNALPFP:22448
Component DescriptionBBS005JL
IGNITION COIL & POWER TRANSISTOR
The ignition signal from the ECM is sent to and amplified by the
power transistor. The power transistor turns ON and OFF the ignition
coil primary circuit. This ON/OFF operation induces the proper high
voltage in the coil secondary circuit.
PBIB2132E