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Home >> Chevrolet >> 2004 >> Avalanche 2500 >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 2 (Automatic Transmission - 4L60-E/4L65-E Diagnosis (DTC P0218 To DTC P2771)) >> Diagnosis >> DTC P2771 >> Test Description

Test Description

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

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

  1. 3:  This step tests for a short to ground in the 4WD low signal circuit.
  2. 4:  This step tests for an open in the 4WD low signal circuit or a faulty transfer case control module.
DTC P2771

Step Action Value(s) Yes No
1 Did you perform the Diagnostic System Check - Engine Controls? - Go to Step 2  Go to Diagnostic System Check - Engine Controls in Engine Controls - 4.8L, 5.3L and 6.0L
2
  1. Install a scan tool.
  2. Start the engine, parking brake disengaged.
    3. IMPORTANT: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from the PCM.
  3. Record the DTC Freeze Frame and Failure Records.
  4. Clear the DTC.
  5. Place the transmission in NEUTRAL.
  6. Select 4HI on the transfer case selector.
    7. IMPORTANT: It may be necessary to drive the vehicle slightly forward to engage 4LO on the transfer case.
  7. Select 4LO on the transfer case selector.
Does the scan tool 4WD Low display Disabled when you select 4HI, then Enabled when you select 4LO?		 - Go to Intermittent Conditions in Engine Controls - 4.8L, 5.3L and 6.0L Go to Step 3 
3 
  1. Turn OFF the ignition.
  2. Disconnect the transfer case control module connector.
  3. Turn ON the ignition, with the engine OFF.
Does the scan tool 4WD Low indicate Enabled?		 - Go to Step 6  Go to Step 4 
4 
  1. Connect C1-1 of the transfer case control module connector.
  2. Observe the scan tool 4WD Low.
Does the scan tool 4WD Low indicate Enabled when the 4WD low signal circuit, is grounded?		 - Go to Step 5  Go to Step 7 
5 Replace the transfer case control module. Refer to Transfer Case Shift Control Module Replacement in Transfer Case - NVG 246-NP8.
Did you complete the replacement?		 - Go to Step 9  -
6 Test the 4WD low signal circuit for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 9  Go to Step 8 
7 Test the 4WD low signal circuit for an open. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 9  Go to Step 8 
8 Replace the powertrain control module (PCM). Refer to Powertrain Control Module (PCM) Replacement in Engine Controls - 4.8L, 5.3L and 6.0L.
Did you complete the replacement?		 - Go to Step 9  -
9 Perform the following procedure in order to verify the repair:
  1. Select DTC.
  2. Select Clear Info.
  3. Operate the vehicle under the following conditions:
    1. Select 4LO on the transfer case selector.
    2. Drive the vehicle in D4.
    3. Verify that the speed ratio is 2.5-2.9 for 1.5 seconds.
    4. Select 2HI or 4HI on the transfer case selector.
    5. Drive the vehicle in D4 with the TCC ON.
    6. Verify that the speed ratio is 0.8-1.2 for 5 seconds.
  4. Select Specific DTC.
  5. Enter DTC P2771.

Has the test run and passed?		 - Go to Step 10  Go to Step 2 
10 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 in Engine Controls - 4.8L, 5.3L and 6.0L System OK
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