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Home >> Chevrolet >> 2012 >> Tahoe Base, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 372 (Automatic Transmission - 4L80-E/4L85-E, Diagnosis (P0218 To P2771)) >> Diagnosis >> DTC P0894 >> Test Description

Test Description

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The numbers below refer to the step numbers on the diagnostic table.

  1. 3:  This step tests the indicated range signal to the actual selected range. A faulty TFP manual valve position switch can set a DTC P0894.
  2. 4:  This step tests for excessive TCC slip speed while in a commanded TCC lock-up state and in fourth gear; and confirms that the fault is present.
  3. 5:  This step tests for excessive TCC slip speed while in a commanded TCC lock-up state and in third gear.
  4. 6:  This step tests for a sticking TCC shift valve.
  5. 7:  This step tests for proper transmission line pressure.
DTC P0894

Step Action Value(s) Yes No
1 Did you perform the Diagnostic System Check - Engine Controls? - Go to Step 2  Go to Diagnostic System Check - Engine Controls in Engine Controls - 4.8L, 5.3L, and 6.0L
2 Perform the Transmission Fluid Checking Procedure.
Refer to Transmission Fluid Checking Procedure .
Did you perform the Transmission Fluid Checking Procedure?		 - Go to Step 3  Go to Transmission Fluid Checking Procedure
3 
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
    3. IMPORTANT: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from the PCM.
  3. Record the Freeze Frame and Failure Records.
  4. Clear the DTCs.
  5. Start and idle the engine at normal operating temperature.
  6. Apply the brake pedal.
  7. Select each transmission range: D1, D2, D3, D4, N, R, and P.

    Refer to Transmission Fluid Pressure (TFP) Manual Valve Position Switch Logic .

Does each selected transmission range match the scan tool TFP switch A/B/C display?		 - Go to Step 4  Go to DTC P1810 
4  Drive the vehicle under the following conditions:
  • The TFT is 20-130°C (50-266°F).
  • The transmission is in D4.
  • The TCC duty cycle is greater than 80 percent.
  • The throttle angle is 10-80 percent.

At any time is the TCC slip speed greater than the specified value for 10 seconds?		 120 RPM Go to Step 5  Go to Diagnostic Aids
5  Drive the vehicle under the following conditions:
  • The transmission is in D3.
  • Command the TCC ON with the scan tool.
  • The TP angle is 10-80 percent.

At any time is the TCC slip speed greater than the specified value for 10 seconds?		 120 RPM Go to Step 7  Go to Step 6 
6  Repeat the procedure in Step 4. Drive the vehicle under the following conditions:
  • The transmission is in D4.
  • The TCC duty cycle is greater than 80 percent.
  • The TP angle is 10-80 percent.

Is the TCC slip speed greater than the specified value?		 120 RPM Go to Step 8  Go to Diagnostic Aids
7 
  1. Connect the J 21867  pressure gage to the transmission line pressure tap.
  2. Perform the Line Pressure Check Procedure.
Refer to Line Pressure Check Procedure .Is the line pressure within specifications?		 - Go to Step 8  Go to Symptoms - Automatic Transmission
8
  1. Inspect the transmission for the following conditions:
    • TCC enable valve mechanically stuck OFF
    • TCC solenoid valve O-ring seals worn
    • TCC shift valve stuck in the released position

      Refer to Torque Converter Clutch (TCC) Valve and Spring Replacement .

    • Turbine shaft oil holes plugged
    • Turbine shaft seals leaking

      Refer to Turbine Shaft Disassemble in Transmission Unit Repair article.

    • Converter limit valve plug leaking

      Refer to Transmission Oil Pump Disassemble in Transmission Unit Repair article.

    • TCC PWM solenoid valve mechanically stuck OFF
    • TCC regulator apply valve stuck in the released position

      Refer to Control Valve Body Cleaning and Inspection in Transmission Unit Repair article.

  2. Repair the condition as necessary.
Did you complete the repair?		 - Go to Step 10  Go to Step 9 
9
  1. Inspect the transmission for the following conditions:
    • Fourth clutch plates damaged or burned

      Refer to Clutch Plate Diagnosis .

    • Fourth clutch piston seals leaking
    • Fourth clutch cup plug leaking
    • Fourth clutch retainer ring not seated

      Refer to Forward Clutch Assembly Disassemble in Transmission Unit Repair article.

    • Overrun clutch plates damaged or burned

      Refer to Clutch Plate Diagnosis .

    • Overdrive clutch roller assembly not holding

      Refer to Overrun Clutch Assembly Disassemble in Transmission Unit Repair article.

  2. Repair the condition as necessary.
Did you complete the repair?		 - Go to Step 10  -
10 Perform the following procedure in order to verify the repair:
  1. Select DTC.
  2. Select Clear Info.
  3. Operate the vehicle under the following conditions:
    • Ensure that TFT is 20-130°C (50-266°F).
    • Drive the vehicle in 4th gear, with the TCC commanded ON.
    • The throttle angle is 10-100 percent.
    • TCC slip speed must be -25 to +25 RPM for 10 seconds.
  4. Select Specific DTC.
  5. Enter DTC P0894.

Has the test run and passed?		 - Go to Step 11  Go to Step 2 
11 With the scan tool, observe the stored information, capture info and DTC info.
Does the scan tool display any DTCs that you have not diagnosed?		 - Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 4.8L, 5.3L, and 6.0L System OK
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