P0734
DTC P0734 A/T 4TH GEAR FUNCTIONDescription
^This malfunction will not be detected while the A/T CHECK indicator lamp is indicating another self-diagnosis malfunction.
- This malfunction is detected when the A/T does not shift into fourth 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
- This is an OBD-II self-diagnostic item.
- Diagnostic trouble code "A/T 4TH OR 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
- Shift solenoid valve A (On stick.)
- Shift solenoid valve B (On stick.)
- Shift solenoid valve C (On stick.)
- Pressure control solenoid valve A (On stick.)
- Forward and direct clutch assembly
- U/D clutch
- U/D brake
- 2nd coast brake
- One-way clutch No.1
- Hydraulic control circuit
DTC Confirmation Procedure
CAUTION:
- Always drive vehicle at a safe speed.
- Be careful not to rev engine into the red zone on the tachometer.
NOTE: If "DTC Confirmation Procedure" has been previously performed, always turn ignition switch "OFF" and wait at least 10 seconds before performing the next test.
After the repair, perform the following procedure to confirm the malfunction is eliminated.
WITH CONSULT-II
1. Start engine and select "A/T" with "DATA MONITOR" mode in CONSULT-II.
2. Make sure that ATF temperature is within the range below.
FLUID TEMP: More than 20°C (68°F) If out of range, drive the vehicle to warm up the fluid.
3. Accelerate vehicle to maintain the following conditions for at least 10 consecutive seconds.
SLCT LVR POSI: "D" position
GEAR: 4th position
[Vehicle speed and accelerator angle: 4th gear position retainable condition. (Refer to AT-312. "VEHICLE SPEED WHEN SHIFTING GEARS".)] Driving location: Driving the vehicle uphill (increased engine load) will help maintain the driving conditions required for this test.
4. If DTC is detected, go to AT-133 "Diagnostic Procedure".
WITH GST
Follow the procedure "With CONSULT-II".
AT-4THSIG-01:
AT-4THSIG:
Wiring Diagram-AT-4THSIG
Diagnostic Procedure
1. CHECK EACH SHIFT SOLENOID VALVE CIRCUIT
- Perform "Diagnostic Procedure" for the following DTCs.
- "DTC P0750 SHIFT SOLENOID VALVE A" (Refer to AT-151. "Diagnostic Procedure".) P0750
- "DTC P0755 SHIFT SOLENOID VALVE B" (Refer to AT-156. "Diagnostic Procedure".) P0755
- "DTC P0760 SHIFT SOLENOID VALVE C" (Refer to AT-161 "Diagnostic Procedure".) P0760
OK or NG
OK >>GO TO 2.
NO >>Repair or replace damaged parts.
2. CHECK PRESSURE CONTROL SOLENOID VALVE A CIRCUIT
Perform "Diagnostic Procedure" for DTC P0745. Refer to AT-146. "Diagnostic Procedure". P0745
OK or NG
OK >>GO TO 3.
NO >>Repair or replace damaged parts.
3. CHECK MALFUNCTIONING ITEM
1. Control valve assembly. Refer to "Control Valve Assembly".
2. Disassembly A/T. Refer to "DISASSEMBLY".
3. Check the following item:
- Forward and direct clutch assembly. Refer to "DISASSEMBLY".
- 2nd coast brake. Refer to "Oil Pump. 2nd Coast Brake & 2nd Brake" "One-Way Clutch Outer Race Sub Assembly & 2nd Coast Brake Hub & One-Way Clutch No.1".
- U/D brake. Refer to "DISASSEMBLY".
- U/D clutch. Refer to "DISASSEMBLY".
- One-way clutch No. 1. Refer to "One-Way Clutch Outer Race Sub Assembly & 2nd Coast Brake Hub & One-Way Clutch No.1".
OK or NG
OK >> GO TO 4.
NG >>Repair or replace damaged parts.
4. CHECK DTC
Perform "DTC Confirmation Procedure". Refer to AT-130, "DTC Confirmation Procedure".
OK or NG
OK >> INSPECTION END
NG >>Replace the control valve assembly. Refer to "Control Valve Assembly".