DTC P0731 A/T 1ST GEAR FUNCTION
AT-131
[RE4F04B]
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Revision: November 2006
2006 Altima
DTC P0731 A/T 1ST GEAR FUNCTION
PFP:31940
Description
ECS00976
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This is an OBD-II self-diagnostic item and not available in TCM self-diagnosis.
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This malfunction will not be detected while the A/T check (position) indicator lamp is indicating another
self-diagnosis malfunction.
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This malfunction is detected when the A/T does not shift into first gear position as instructed by the TCM.
This is not caused by electrical malfunction (circuits open or shorted) but by mechanical malfunction such
as control valve sticking, improper solenoid valve operation, etc.
On Board Diagnosis Logic
ECS00977
This diagnosis monitors actual gear position by checking the torque converter slip ratio calculated by TCM as
follows:
Torque converter slip ratio = A x C/B
A: Output shaft revolution signal from revolution sensor
B: Engine speed signal from ECM
C: Gear ratio determined as gear position which TCM supposes
If the actual gear position is higher than the position (1st) supposed by TCM, the slip ratio will be more than
normal. In case the ratio exceeds the specified value, TCM judges this diagnosis malfunction.
This malfunction will be caused when either shift solenoid valve A is stuck open or shift solenoid valve B is
stuck open.
Gear positions supposed by TCM are as follows.
In case of gear position with no malfunctions: 1 , 2, 3 and 4 positions
In case of gear position with shift solenoid valve A stuck open: 2* , 2, 3 and 3 positions
In case of gear position with shift solenoid valve B stuck open: 4* , 3, 3 and 4 positions to each gear position
above
*: P0731 is detected.
Diagnostic trouble code A/T 1ST GR FNCTN with CONSULT-II or P0731 without CONSULT-II is detected
when A/T cannot be shifted to the 1st gear position even if electrical circuit is good.
Possible Cause
ECS00978
Check the following items.
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Shift solenoid valve A
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Shift solenoid valve B
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Each clutch
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Hydraulic control circuit
Diagnostic Trouble Code (DTC) Confirmation Procedure
ECS00979
CAUTION:
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Always drive vehicle at a safe speed.
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Be careful not to rev engine into the red zone on the tachometer.
NOTE:
If “DTC Confirmation Procedure” has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
TESTING CONDITION:
Always drive vehicle on a level road to improve the accuracy of test.
After the repair, perform the following procedure to confirm the malfunction is eliminated.
Gear position
1
2
3
4
Shift solenoid valve A
ON (Closed)
OFF (Open)
OFF (Open)
ON (Closed)
Shift solenoid valve B
ON (Closed)
ON (Closed)
OFF (Open)
OFF (Open)
