On Board Diagnosis Logic
NHAT0222
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 A is stuck
open or 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 posi-
tions
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 closed: 1,
2, 2 and 1* positions to each gear position above
*: P0734 is detected.
And also, this malfunction will be caused when line pressure is
lower than normal such as when line pressure solenoid valve is
stuck open.
Diagnostic trouble code A/T 4TH GR FNCTN with CONSULT-II or
P0734 without CONSULT-II is detected when A/T cannot be shifted
to the 4th gear position even if electrical circuit is good.
Possible Cause
NHAT0223
Check the following items.
I
Shift solenoid valve A
I
Shift solenoid valve B
I
Line pressure solenoid valve
I
Each clutch
I
Hydraulic control circuit
GI
MA
EM
LC
EC
FE
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
DTC P0734 A/T 4TH GEAR FUNCTION
On Board Diagnosis Logic
AT-149