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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 P0743 >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis 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. 2:  This step tests the system voltage.
  2. 6:  This step tests the resistance at the TCC PWM solenoid.
DTC P0743

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.
    • This diagnostic table should only be used if the DTC is currently failing. If the DTC is not active, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems until the DTC becomes active.
  3. Record the DTC Freeze Frame and Failure Records.
  4. Clear the DTC.
  5. Using the scan tool, measure ignition voltage.
Is 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. Using a DMM, measure the resistance between connector C2 terminal 29 and connector C2 terminal 32.
Is the resistance reading within the specified value?		 10.5 ohm @ 20°C (68°F) Go to Step 4  Go to Step 5 
4
  1. Turn the ignition OFF.
  2. Disconnect the TCM connector C2 (RED).
  3. Install the J 39700  breakout box and the J 43799  breakout box adapter. Do not connect the vehicle side C2 (RED) connector to the J 43799  .
  4. Using a 12-volt unpowered test light, place the leads on terminals 29 and 32 of the J 39700  .
  5. Turn the ignition ON, with the engine OFF.
  6. Use the scan tool in Solenoid Test Mode to command TCC PWM solenoid ON and OFF.
Does the test lamp turn ON and OFF when commanded?		 - Go to Diagnostic Aids Go to Step 11 
5
  1. Turn the ignition OFF.
  2. Connect the C2 (RED) connector to the TCM.
  3. Disconnect the transmission 20-way connector.
  4. Turn the ignition ON, with the engine OFF. Additional DTCs may set.
  5. Using a 12-volt unpowered test light, place the leads at the engine side of the transmission 20-way connector terminals J and S.
  6. Use the scan tool in Solenoid Test Mode to command the TCC PWM solenoid ON and OFF.
Does the test lamp turn ON and OFF when commanded?		 - Go to Step 6  Go to Step 8 
6 
  1. Turn the ignition OFF.
  2. Using a DMM, measure the resistance between terminals J and S of the transmission 20-way connector.
Is the solenoid resistance within the specified value?		 10.5 ohm @ 20°C (68°F) Go to Diagnostic Aids Go to Step 7 
7
  1. Remove the oil pan. Refer to Oil Pan Replacement .
  2. Remove the internal wiring harness at the TCC PWM solenoid connector.
  3. Using a DMM, measure the resistance of the TCC PWM solenoid.
Is the solenoid resistance within the specified value?		 10.5 ohm @ 20°C (68°F) Go to Step 9  Go to Step 10 
8 Repair the engine wiring harness. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair		 - Go to Step 12  -
9 Replace the AT internal wiring harness. Refer to Wiring Harness Replacement .
Did you complete the replacement?		 - Go to Step 12  -
10 Replace the TCC PWM 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 12  -
11
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 12  -
12 Perform the following procedure in order to verify the repair:
  1. Clear the DTC.
  2. Drive the vehicle under normal operating conditions.
  3. Using the scan tool, monitor TCC slip speed. The TCC must engage/disengage when commanded.
  4. Select Specific DTC.
  5. Enter DTC P0743.

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