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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1072 (Automatic Transmission - ALLISON, Diagnosis (DTC P0736 To DTC P0872)) >> Diagnosis >> DTC P0777 >> 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 for proper ignition voltage.
  2. 4:  This step tests for erratic speed sensor readings or signal dropout.
  3. 5:  This step tests for internal hydraulic leakage.
  4. 6:  This step tests for clutch capacity.
DTC P0777

Step Action Value Yes No
Schematic Reference: Automatic Transmission Controls Schematics
1 Did you perform the Diagnostic System Check - Automatic Transmission? - Go to Step 2  Go to Diagnostic System Check - Automatic Transmission
2 Measure the transmission fluid level. Refer to Transmission Fluid Checking Procedure .
Is the transmission fluid level correct?		 - Go to Step 3  Go to Transmission Fluid Checking Procedure
3 
  1. Install the scan tool.
  2. Start the engine.
    3. IMPORTANT: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records for reference. The Clear Info function will erase the data.
  3. Record the DTC Freeze Frame and Failure Records.
  4. Clear the DTC.
  5. Using the scan tool, measure ignition voltage.
Is the voltage within the specified range?		 9-18 V Go to Step 4  Go to DTC P0562 for low voltage or DTC P0563 for high voltage
4 
  1. Start the engine.
  2. Drive the vehicle under normal operating conditions.
  3. Using the scan tool, monitor engine, turbine and output speed sensor readings.
Is speed sensor data erratic?		 - Go to the appropriate speed sensor DTC Go to Step 5 
5 
  1. Connect a 2,000 kPa (300 psi) pressure gage to the line pressure tap. Refer to Line Pressure Check Procedure .
  2. Use the scan tool, in Clutch Test Mode, to cycle through all transmission ranges with the engine at idle and vehicle brakes applied. Record line pressure in each range.
Was the line pressure low in a specific range or in ranges where the same clutch was applied?		 - Go to Low Main Line Pressure in All Ranges Go to Step 6 
6 
NOTE: Refer to Transmission Stall Test Notice in Cautions and Notices.
Conduct a clutch test for all forward ranges. Refer to Clutch Test .Did turbine speed remain at zero in all ranges?		 - Go to Diagnostic Aids Go to Step 7 
7
  1. Remove the transmission oil pan. Refer to Automatic Transmission Fluid/Filter Replacement .
  2. Inspect for signs of clutch failure.
Are there signs of a clutch failure?		 - Go to Step 8  Go to Step 9 
8 Remove the transmission for overhaul or replacement. Refer to Transmission Replacement (With 6.6L Engine) or Transmission Replacement (With 8.1L (L18) Engine) .
Did you complete the repair or replacement?		 - Go to Step 11  -
9 Inspect for a stuck or sticking B trim valve. Refer to Control Valve Body Cleaning and Inspection .
Did you find and correct a condition?		 - Go to Step 11  Go to Step 10 
10 Replace B solenoid. Refer to Control Valve Solenoid Replacement (Solenoid A, B) or Control Valve Solenoid Replacement (Solenoid C, D, E, F, G) .
Did you complete the replacement?		 - Go to Step 11  -
11 Perform the following procedure in order to verify the repair:
  1. Clear the DTC.
  2. Start the engine.
  3. Use the scan tool to reset adaptive values for all shifts.
  4. Operate the vehicle in all ranges under normal driving conditions.
  5. Select Specific DTC.
  6. Enter DTC P0777.

Has test run and passed?		 - System OK Go to Step 1 
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