AT-158
[RE4F04B]
DTC P0744 A/T TCC S/V FUNCTION (LOCK-UP)
Revision: November 2006
2006 Altima
DTC P0744 A/T TCC S/V FUNCTION (LOCK-UP)
PFP:31940
Description
ECS00980
●
This is an OBD-II self-diagnostic item and not available in TCM self-diagnosis.
●
This malfunction will not be detected while the A/T check position indicator lamp is indicating another self-
diagnosis malfunction.
●
This malfunction is detected when the A/T does not shift into fourth gear position or the torque converter
clutch does not lock up 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, malfunctioning oil pump or torque converter clutch, etc.
CONSULT-II REFERENCE VALUE IN DATA MONITOR MODE
Remarks: Specification data are reference values.
On Board Diagnosis Logic
ECS00981
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 much lower than the position (4th) supposed by TCM, the slip ratio will be much
less than normal. In case the ratio does not reach the specified value, TCM judges this diagnosis malfunction.
This malfunction will be caused when shift solenoid valve B is stuck closed.
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 B stuck closed: 1, 2, 2 and 1* positions to each gear position
above
*: P0744 is detected.
Diagnostic trouble code A/T TCC S/V FNCTN with CONSULT-II or P0744 without CONSULT-II is detected
when A/T cannot perform lock-up even if electrical circuit is good.
Possible Cause
ECS00982
Check the following items.
●
Line pressure solenoid valve
●
Torque converter clutch solenoid valve
●
Each clutch
●
Hydraulic control circuit
Diagnostic Trouble Code (DTC) Confirmation Procedure
ECS00983
CAUTION:
Always drive vehicle at a safe speed.
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.
After the repair, perform the following procedure to confirm the malfunction is eliminated.
Monitor item
Condition
Specification
Torque converter clutch
solenoid valve duty
Lock-up OFF
↓
Lock-up ON
Approximately 4%
↓
Approximately 94%
