AUTOMATIC TRANSAXLE SYSTEM, Diagnostic DTC:P0746

SYSTEM DESCRIPTION

The TCM uses the vehicle speed signal and signals from the transmission speed sensors (NC, NT) to detect the actual gear (1st, 2nd, 3rd, 4th, 5th or 6th gear).

The TCM compares the actual gear with the shift schedule in the TCM memory to detect mechanical malfunctions of the shift solenoid valves and transmission valve body assembly.

MONITOR DESCRIPTION

The TCM commands gear shifts by turning the shift solenoid valves on and off. According to the input shaft revolution (speed), intermediate (counter) shaft revolution (speed) and output shaft revolution (speed), the TCM detects the actual gear (1st, 2nd, 3rd, 4th, 5th or 6th gear). When the gear commanded by the TCM and the actual gear are not the same, the TCM illuminates the MIL and stores a DTC.

CAUTION / NOTICE / HINT

PROCEDURE

1. CHECK OTHER DTCS OUTPUT (IN ADDITION TO DTC P0746)

   
   

   1. Connect the GTS to the DLC3.

   2. Turn the engine switch on (IG).

   3. Turn the GTS on.

   4. Enter the following menus: Powertrain / ECT / Trouble Codes.

      
      Powertrain > ECT > Trouble Codes

   5. Read the DTCs using the GTS.

      Result
      Result Proceed to Only DTC P0746 is output A DTC P0746 and other DTCs are output B

      Tech Tips

      If a solenoid is stuck OFF, DTCs for several solenoids including the malfunctioning solenoid will be stored.

   
   

   B

   PERFORM ACTIVE TEST USING GTS (CONTROL THE SHIFT POSITION) Click here

   A

2. INSPECT SHIFT SOLENOID VALVE SL1

   
   
   1. 

      *1	Shift Solenoid Valve SL1

      Remove the shift solenoid valve SL1.

      Click here

   2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition 1 - 2 20°C (68°F) 5.0 to 5.6 Ω

   3. Connect a positive (+) lead from the battery with a 21 W bulb to terminal 2 and a negative (-) lead to terminal 1 of the shift solenoid valve connector. Check that the valve moves and makes an operating sound.

      OK
      Valve moves and makes an operating sound.

      Result
      Proceed to OK NG

   
   

   NG

   REPLACE SHIFT SOLENOID VALVE SL1 Click here

   OK

3. INSPECT TRANSMISSION VALVE BODY ASSEMBLY

   
   

   1. Check the transmission valve body assembly.

      Click here

      OK
      There is no foreign matter on each valve and they operate smoothly.

      Result
      Proceed to OK NG

   
   

   OK

   REPAIR OR REPLACE AUTOMATIC TRANSAXLE ASSEMBLY Click here

   NG

   REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY Click here

4. PERFORM ACTIVE TEST USING GTS (CONTROL THE SHIFT POSITION)

   Note

   This test should always be performed with at least 2 people.

   
   

   1. Warm up the engine.

   2. Turn the engine switch off.

   3. Connect the GTS to the DLC3.

   4. Turn the engine switch on (IG).

   5. Turn the GTS on.

   6. Enter the following menus: Powertrain / ECT / Active Test / Control the Shift Position.

   7. According to the display on the GTS, perform the Active Test.

      Tech Tips

      Comparing the gear commanded by the Active Test with the actual gear enables confirmation of the problem.

      Click here

      
      Powertrain > ECT > Active Test

      Tester Display	Measurement Item	Control Range	Diagnostic Note
      Control the Shift Position	Operates the shift solenoid valves to allow gears to be selected manually.	Press "→" button: Upshift occurs Press "←" button: Downshift occurs	Can be used to check the operation of the shift solenoid valves. Upshifts and downshifts should be performed consecutively. A 10-second interval is required between gear changes. Do not downshift at high speeds. Doing so will damage the automatic transaxle. [Vehicle Condition] 50 km/h (31 mph) or less

      
      Powertrain > ECT > Active Test

      Tester Display
      Control the Shift Position

      Note

      
      

      • This Active Test can be performed when the vehicle is stopped.

      • When shifting gears using the Active Test, do not operate the accelerator pedal for 2 seconds before and after shifting gears.

      Tech Tips

      The gear commanded by the TCM is shown in the Data List / Shift Status display on the GTS.

   8. Check the vehicle speed and gear when the engine speed is 1000 rpm.

      Tech Tips

      As the torque converter clutch has not engaged, it may be difficult to obtain the speeds specified for 4th, 5th, and 6th gear, however a difference of speed should still be evident following each gear change.

      Standard
      1st 2nd 3rd 4th 5th 6th 8 to 12 km/h (5 to 7 mph) 15 to 19 km/h (9 to 12 mph) 21 to 25 km/h (13 to 16 mph) 31 to 35 km/h (19 to 22 mph) 44 to 48 km/h (27 to 30 mph) 52 to 56 km/h (32 to 35 mph)

   9. Compare the TCM commanded gear and the actual gear.

      Result

      Actual Gear during Malfunction TCM Commanded Gear Proceed to 1st 2nd 3rd 4th 5th 6th Shift solenoid valve SL1 Stuck ON 1st 2nd 3rd 4th 4th 4th A Stuck OFF N*1 N*1 N*1 N*1 5th 6th Shift solenoid valve SL2 Stuck ON 4th 4th 4th 4th 5th 6th B Stuck OFF 1st 2nd 3rd 1st N*1 N*1 Shift solenoid valve SL3 Stuck ON 2nd 2nd 3rd 4th 5th 6th C Stuck OFF 1st 1st 3rd 4th 5th N*1 Shift solenoid valve SL4 Stuck ON 3rd 3rd 3rd 4th 5th 5th D Stuck OFF 1st 2nd 1st 4th N*1 6th Shift solenoid valve SLT Stuck ON N*2 N*2 N*2 N*2 N*2 N*2 E Stuck OFF*3 1st 2nd 3rd 4th 5th 6th

      Tech Tips

      
      

      • *1: Neutral

      • *2: If the shift solenoid valve SLT is stuck on, the line pressure will be low. Therefore, the amount of torque that can be transmitted by each gear will be lower than the normal limit. When the engine power exceeds this limit, the engine speed will increase freely.

      • *3: When the shift solenoid valve SLT is stuck off, gear shifting will be normal.

   
   

   A

   GO TO STEP 2 Click here

   B

   GO TO DTC CHART (DTC P0776) Click here

   C

   GO TO DTC CHART (DTC P0796) Click here

   D

   GO TO DTC CHART (DTC P2808) Click here

   E

   GO TO DTC CHART (DTC P2714) Click here