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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 938 (Automatic Transmission - ALLISON - DTC P0733 To DTC P0873) >> DTC P0776 >> Test Description

Test Description

WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

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.
  3. 5:  This step tests for internal hydraulic leakage.
  4. 6:  This step tests for clutch capacity.
DTC P0776

Step Action Value Yes No
Schematic Reference: Automatic Transmission Controls Schematics
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2 Measure the transmission fluid level. Refer to Transmission Fluid Check .
Is the transmission fluid level correct?		 - Go to Step 3  Go to Transmission Fluid Check
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 OSS 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 .
  2. Using the scan tool in clutch test mode, 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  Refer to Transmission Stall Test Notice .
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 and Filter Replacement .
  2. Inspect for signs of clutch failure.
Are there signs of clutch failure?		 - Go to Step 8  Go to Step 9 
8 Remove the transmission for overhaul or replacement. Refer to Transmission Replacement .
Did you complete the repair or replacement?		 - Go to Step 11  -
9 Inspect for a stuck or sticking PCS2 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 PSC2. Refer to Control Valve Solenoid Replacement (PCS1 and PCS2) or Control Valve Solenoid Replacement (SS1, SS2, SS3, TCC, and MAIN MOD) .
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 P0776.

Has test run and passed?		 - Go to Step 12  Go to Step 2 
12 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 - Vehicle System OK
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