P0734

Description

- This malfunction will not be detected while the OD OFF 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 Reference Value in Data Monitor Mode

Remarks: Specification data are reference values.







On Board Diagnosis Logic

- This is an OBD-II self-diagnostic item.
- Diagnostic trouble code "P0734 4GR INCORRECT RATIO" with CONSULT is detected when A/T cannot be shifted to the 4GR position even if electrical circuit is good.
- 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 output speed 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 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 closed: 1, 2, 2 and 1* positions to each gear position above
*: "P0734 4GR INCORRECT RATIO" is detected.


Possible Cause

- Shift solenoid valve A
- Shift solenoid valve B
- Line pressure solenoid valve
- Each clutch
- Hydraulic control circuit


DTC Confirmation Procedure


CAUTION:
- Always drive vehicle at a safe speed.
- If performing this "DTC Confirmation Procedure" again, always turn ignition switch OFF and wait at least 10 seconds before continuing.
After the repair, perform the following procedure to confirm the malfunction is eliminated.

WITH CONSULT

1.Start engine and select "DATA MONITOR" mode for "TRANSMISSION" with CONSULT.
2.Touch "START".
3.Make sure that output voltage of A/T fluid temperature sensor is within the range below.





If out of range, drive the vehicle to decrease the voltage (warm up the fluid) or stop engine to increase the voltage (cool down the fluid).
4.Select "4TH GR FNCTN P0734" of "DTC & SRT CONFIRMATION" mode for "TRANSMISSION" with
CONSULT and touch "START".
5.Accelerate vehicle to 55 to 65 km/h (34 to 40 MPH) under the following conditions and release the accelerator pedal completely.





-Make sure that "GEAR" shows "3" after releasing pedal.
6.Depress accelerator pedal steadily with 1.0/8 - 2.0/8 of "THROTTLE POSI" from a speed of 55 to 65 km/h (34 to 40 MPH) until "TESTING" has turned to "STOP VEHICLE" or "COMPLETED". (It will take approximately 3 seconds.)
If the check result NG appears on CONSULT screen, go to .
If "STOP VEHICLE" appears on CONSULT screen, go to following step.
-Make sure that "GEAR" shows "4" when depressing accelerator pedal with 1.0/8 - 2.0/8 of "THROTTLE POSI".
-If "TESTING" does not appear on CONSULT for a long time, select "SELF-DIAG RESULTS" for "TRANSMISSION". In case a DTC other than "P0734 4GR INCORRECT RATIO" is shown, refer to AT-74, "CONSULT Function (TRANSMISSION)". Automatic Transmission






7.Stop vehicle.
8.Follow the instruction displayed. (Check for normal shifting referring to the table below.)





9.Make sure that "OK" is displayed. (If "NG" is displayed, refer to "Diagnostic Procedure".)
.
Automatic Transmission.

WITH GST

Follow the procedure "WITH CONSULT".


Diagnosis Procedure

3 TO D4)

1. CHECK SHIFT-UP (D






During Automatic Transmission.
Does A/T shift from D3 to D4 at the specified speed?
YES- GO TO 11.
NO- GO TO 2.

2. CHECK LINE PRESSURE

Perform line pressure test. Automatic Transmission.
OK or NG
OK- GO TO 3.
NG- GO TO 7.

3. CHECK VALVE RESISTANCE

1.Remove control valve assembly. Service and Repair.
-Shift solenoid valve A
-Shift solenoid valve B





2.Check resistance between terminal cord assembly harness connector terminals and ground. P0750 and P0755.





OK or NG
OK- GO TO 4.
NG- Replace solenoid valve assembly.

4. CHECK VALVE OPERATION

1.Remove control valve assembly. Service and Repair.
-Shift solenoid valve A
-Shift solenoid valve B





2.Check solenoid valve by listening for its operating sound while applying battery voltage to the terminals and ground. Refer to
P0750 and P0755.
OK or NG
OK- GO TO 5.
NG- Replace solenoid valve assembly.

5. CHECK CONTROL VALVE

1.Disassemble control valve assembly. Control Valve Assembly.
2.Check to ensure that:
-Valve, sleeve and plug slide along valve bore under their own weight.
-Valve, sleeve and plug are free from burrs, dents and scratches.
-Control valve springs are free from damage, deformation and fatigue.
-Hydraulic line is free from obstacles.
OK or NG
OK- GO TO 6.
NG- Repair control valve.
3 TO D4)

6. CHECK SHIFT-UP (D






During Automatic Transmission.
Does A/T shift from D3 to D4 at the specified speed?
YES- GO TO 11.
NO- Check control valve again. Repair or replace control valve assembly.

7. CHECK VALVE RESISTANCE

1.Remove control valve assembly. Service and Repair.
-Line pressure solenoid valves





2.Check resistance between terminal cord assembly harness connector terminal and ground. Pressure Control Solenoid A.





OK or NG
OK- GO TO 8.
NG- Replace solenoid valve assembly.

8. CHECK VALVE OPERATION

1.Remove control valve assembly. Service and Repair.
-Line pressure solenoid valves





2.Check solenoid valve by listening for its operating sound while applying battery voltage to the terminal and ground. Pressure Control Solenoid A.
OK or NG
OK- GO TO 9.
NG- Replace solenoid valve assembly.

9. CHECK CONTROL VALVE

1.Disassemble control valve assembly. Control Valve Assembly.
2.Check line pressure circuit valves for sticking.
-Pilot valve
-Shift solenoid valve A
-Shift solenoid valve B
OK or NG
OK- GO TO 10.
NG- Repair control valve.
3 TO D4)

10. CHECK SHIFT-UP (D






During Automatic Transmission.
Does A/T shift from D3 to D4 at the specified speed?
YES- GO TO 11.
NO- Check control valve again. Repair or replace control valve assembly.

11. CHECK DTC

Perform .
OK or NG
OK-INSPECTION END
NG- Perform Automatic Transmission again and return to the start point of this test group.