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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 P0763 >> Test Description

Test Description

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

  1. 2:  This step tests ignition voltage.
  2. 3:  This step tests the command signal from the TCM.
  3. 4:  This step tests the resistance value of the external harness and solenoid.
  4. 5:  This step tests the resistance value of the solenoid and internal wiring harness.
  5. 6:  This step tests the resistance value of the solenoid.
DTC P0763

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 
  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 3  Go to DTC P0562 for low voltage or DTC P0563 for high voltage
3 
  1. Turn the ignition OFF.
  2. Disconnect the C2 connector (RED) at the TCM.
  3. Install the J 39700  breakout box and the J 43799  breakout box adapter.
  4. Using a DMM, measure voltage between connector C2 terminal 26 and terminal 31.
  5. Turn ON the ignition, with the engine OFF.
  6. Using the scan tool, command C solenoid to ON.
Is voltage within the range specified when C solenoid is commanded ON?		 B+ Go to Step 4  Go to Step 10 
4 
  1. Turn the ignition OFF.
  2. Using the DMM, measure the resistance between connector C2 terminal 26 and terminal 31.
Is the resistance reading within the specified range?		 22.0 ohm @ 20°C (68°F) Go to Diagnostic Aids Go to Step 5 
5 
  1. Turn the ignition OFF.
  2. Connect the C2 connector (RED) at the TCM.
  3. Disconnect the wiring harness from the transmission 20-way connector.
  4. Install a DMM and measure the resistance on the transmission side of the 20-way connector terminals A and C.
Is resistance within the specified range?		 22.0 ohm @ 20°C (68°F) Go to Step 6  Go to Step 7 
6  Inspect the engine wiring harness circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 11  -
7
  1. Remove the oil pan. Refer to Oil Pan Replacement .
  2. Remove the AT internal wiring harness at C solenoid connector.
  3. Using the DMM, measure the resistance of C solenoid.
Is the solenoid resistance within the specified value?		 22.0 ohm @ 20°C (68°F) Go to Step 8  Go to Step 9 
8 Replace the AT internal wiring harness. Refer to Wiring Harness Replacement .
Did you complete the replacement?		 - Go to Step 11  -
9 Replace C 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  -
10
IMPORTANT: In most cases, the TCM is not at fault. Investigate thoroughly before replacing the TCM.
Replace the TCM. Refer to Transmission Control Module (TCM) Replacement .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. Drive the vehicle under normal operating conditions.
  3. Select Specific DTC.
  4. Enter DTC P0763.

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