LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1067 (Automatic Transmission - 4L60-E/4L65-E Diagnosis (P0894-P2797)) >> Diagnosis >> DTC P2771 >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 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 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, active transfer case vehicles, or transfer case switch, non-active transfer case vehicles.
DTC P2771

Step Action Values 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 - 4.3L or 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 - 4.3L or 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, active transfer case vehicles, or the transfer case switch connector, non-active transfer case vehicles.
  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 a 3 amp fused jumper from the 4WD low signal circuit of the transfer case control module harness to ground.
  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, active transfer case vehicles, or the transfer case selector switch, non-active transfer case vehicles. Refer to Transfer Case Shift Control Module Replacement in Transfer Case - NVG 246-NP8 or Transfer Case Gear Indicator Switch Replacement in Transfer Case - NVG 261-NP2.
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 PCM. Refer to Powertrain Control Module (PCM) Replacement in Engine Controls - 4.3L or 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 - 4.3L or Diagnostic Trouble Code (DTC) List in Engine Controls - 4.8L, 5.3L and 6.0L System OK
scientia non olet · About LEMON Manuals