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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 33 (AUTOMATIC TRANSMISSION - ALLISON - DIAGNOSTICS (DTCs P0878-P2723)) >> DTC P2670 >> Test Description

Test Description

WARNING: This page is about a different variant/trim than selected.

The number below refers to the step number on the diagnostic table.

  1. 3:  This step tests HSD2 supply voltage.
DTC P2670

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
  1. Install the scan tool.
  2. Turn ON the ignition, with the engine OFF.
    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 voltage within the specified value?		 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 80-way connector at the TCM.
  3. Install the J 39700  breakout box, the J-47275  breakout box adapter and the J 47275-1 magnetic overlay. See Special Tools .
  4. Turn ON the ignition, with the engine OFF.
  5. Using the DMM, measure the voltage at terminal 71 and ground.
Is the voltage within the specified value?		 B+ Go to Diagnostic Aids Go to Step 4 
4
  1. Turn the ignition OFF.
  2. Disconnect the AT inline 20-way connector.
  3. Turn ON the ignition, with the engine OFF. Additional DTCs may set.
  4. Using the DMM, measure voltage on the engine side of the AT inline 20-way connector terminal N and ground.
Is the voltage within the specified value?		 B+ Go to Step 5  Go to Step 7 
5
  1. Connect the AT inline 20-way connector.
  2. Remove the transmission oil pan. Refer to Oil Pan Replacement .
  3. Remove the connectors to the PCS2 and the SS1, SS2 and SS3.
  4. Using the DMM, measure the supply voltage of each solenoid connector.
Is the voltage within the specified value at each solenoid terminal?		 B+ Go to Step 6  Go to Step 8 
6 Test the PCS2 and the SS1, SS2 and SS3 for an open or shorted condition. Refer to Temperature vs Resistance (Transmission Fluid Temperature Sensor) or Temperature vs Resistance (Speed Sensor) or Temperature vs Resistance (Solenoid) Solenoid. Refer to Testing for Continuity and Testing for Short to Ground .
Did you find a condition?		 - Go to Step 9  Go to Step 10 
7 Test the HSD2 circuit between the TCM and AT inline 20-way connector for an open or short to ground. Refer to Testing for Continuity and Testing for Short to Ground .
Did you find and correct the condition?		 - Go to Step 11  -
8 Replace the AT internal wiring harness. Refer to Wiring Harness Replacement .
Did you complete the replacement?		 - Go to Step 11  -
9 Replace the open or shorted solenoid. 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  -
10
IMPORTANT: In most cases, the TCM is not at fault. Investigate thoroughly before replacing the TCM.
Replace the TCM. Refer to Control Module References for replacement, setup and programming.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. Select Specific DTC.
  4. Enter DTC P2760.

Has the 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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