ON BOARD DIAGNOSTIC LOGIC
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 position supposed by TCM
1
2
3
4
In case of gear position with no malfunc-
tions
1
2
3
4
In case of gear position with shift solenoid
valve B stuck closed
1
2
2
q
1
q
: P0734 is detected.
Diagnostic trouble code
Malfunction is detected when ...
Check item (Possible cause)
: A/T 4TH GR FNCTN
A/T cannot be shifted to the 4th gear
position even if electrical circuit is good.
I
Shift solenoid valve A
I
Shift solenoid valve B
I
Line pressure solenoid valve
I
Each clutch
I
Hydraulic control circuit
: P0734
SAT014K
SAT971J
DIAGNOSTIC TROUBLE CODE (DTC) CONFIRMA-
TION PROCEDURE
CAUTION:
I
Always drive vehicle at a safe speed.
I
Be careful not to rev engine into the red zone on the
tachometer.
NOTE:
If “DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCE-
DURE” has been previously conducted, always turn ignition
switch “OFF” and wait at least 5 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.
1)
Start engine and select “DATA MONITOR” mode for
“A/T” with CONSULT-II.
2)
Make sure that output voltage of A/T fluid temperature
sensor is within the range below.
FLUID TEMP SEN: 0.4 - 1.5V
If out of range, drive the vehicle to decrease the voltage
(warm up the fluid) or stop engine to increase the volt-
age (cool down the fluid).
GI
MA
EM
LC
EC
FE
PD
FA
RA
BR
ST
RS
BT
HA
EL
IDX
TROUBLE DIAGNOSIS FOR DTC P0734
A/T 4th Gear Function (Cont’d)
AT-109