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).

Then the TCM compares the actual gear with the shift schedule in the TCM memory to detect mechanical problems of the shift solenoid valves and valve body.

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 the DTC.

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

Either of the following conditions is met:

• OFF malfunction:

  Turbine speed - Output speed x Gear ratio

  1,000 rpm or more

  ON malfunction:

  Input (turbine) speed/Intermediate shaft speed when output speed less than 1,000 rpm

  0.998 to 1.138

INSPECTION PROCEDURE

PROCEDURE

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

   1. Connect the Techstream to the DLC3.

   2. Turn the engine switch on (IG).

   3. Turn the Techstream on.

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

   5. Read the DTCs using the Techstream.

      Result
      Display (DTC Output) Proceed to Only "P0746" is output A "P0746" and other DTCs B

      Tech Tips

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

   A

   INSPECT SHIFT SOLENOID VALVE SL1 Click here

   B

2. PERFORM ACTIVE TEST USING TECHSTREAM

   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 Techstream to the DLC3.

   4. Turn the engine switch on (IG).

   5. Turn the Techstream on.

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

   7. According to the display on the Techstream, 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.

      Tester Display	Test Part	Control Range	Diagnostic Note
      Control the Shift Position	Operates the shift solenoid valves to allow gears to 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 (30 mph) or less

      Note

      • This test can be conducted when the vehicle is stopped.

      • When shifting gears using the Active Test function, 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 Techstream.

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

      Tech Tips

      Because the torque converter clutch has not engaged, it may be difficult to obtain the speeds specified in 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 7.5 mph) 15 to 19 km/h (9.3 to 11.8 mph) 21 to 25 km/h (13.0 to 15.5 mph) 31 to 35 km/h (19.3 to 21.7 mph) 44 to 48 km/h (27.3 to 29.8 mph) 52 to 56 km/h (32.3 to 34.8 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 SL1 Stuck ON 1st 2nd 3rd 4th 4th 4th A Stuck OFF N*1 N*1 N*1 N*1 5th 6th Shift solenoid SL2 Stuck ON 4th 4th 4th 4th 5th 6th B Stuck OFF 1st 2nd 3rd 1st N*1 N*1 Shift solenoid SL3 Stuck ON 2nd 2nd 3rd 4th 5th 6th C Stuck OFF 1st 1st 3rd 4th 5th N*1 Shift solenoid SL4 Stuck ON*3 3rd 3rd 3rd 4th 5th 5th D Stuck OFF 1st 2nd 1st 4th N*1 6th Shift solenoid 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 shift solenoid SLT is stuck on, the line pressure will be low. Therefore, the amount of torque that can be transmitted by each gear is lower than the normal limit. When the engine power exceeds this lowered limit, the engine speed will increase freely.

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

   B

   GO TO DTC CHART (RELATED SHIFT SOLENOID VALVE (SL2) PERFORMANCE DTC P0776) Click here

   C

   GO TO DTC CHART (RELATED SHIFT SOLENOID VALVE (SL3) PERFORMANCE DTC P0796) Click here

   D

   GO TO DTC CHART (RELATED SHIFT SOLENOID VALVE (SL4) PERFORMANCE DTC P2808) Click here

   E

   GO TO DTC CHART (RELATED SHIFT SOLENOID VALVE (SLT) PERFORMANCE DTC P2714) Click here

   A

3. INSPECT SHIFT SOLENOID VALVE SL1

   1. Remove shift solenoid valve SL1.

      

   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

      Text in Illustration

      *1	Shift Solenoid Valve SL1

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

      OK
      Valve moves and makes an operating sound.

   NG

   REPLACE SHIFT SOLENOID VALVE SL1 Click here

   OK

4. INSPECT TRANSMISSION VALVE BODY ASSEMBLY

   1. Check the transmission valve body assembly Click here.

      OK
      There are no foreign objects on each valve and they operate smoothly.

   NG

   REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY Click here

   OK

   REPAIR OR REPLACE AUTOMATIC TRANSAXLE ASSEMBLY Click here