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GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15133
Experience:  GM Grand Master Technician 2007. 14 years experience.
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I took my truck over to my buddys shop today to have the

Customer Question

i took my truck over to my buddys shop today to have the codes brought up on his scanner. my four wheel drive stopped working .i have replaced the shift motor and the switch and still nothing, the codes are B0790-06 B2725-08 and C0387-59 can you give me any insight as to where my problem could be next ?
Submitted: 10 months ago.
Category: Chevy
Expert:  Reggie Whiddon replied 10 months ago.

our-Wheel Drive Does Not Engage

Circuit Description

The front axle control circuit consists of an electric motor actuator which engages and disengages the front axle. The front axle actuator consists of the following components within the actuator assembly:

  • A permanent magnetic motor
  • A worm gear controlled plunger
  • A front axle switch
  • An electronic control circuit

The front axle actuator consists of the following circuits:

  • An ignition 3 voltage circuit
  • A ground circuit
  • An axle actuator control circuit
  • An axle switch signal circuit

Whenever a shift to 4WD is selected, the transfer case switch engages the front axle by grounding the axle actuator control circuit.

Test Description

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

  1. Tests for proper ignition 3 voltage to the front axle actuator.

  1. Tests for proper ground at the front axle actuator.

  1. Tests for proper ground at the axle actuator control circuit through the transfer case switch.

  1. Tests the transfer case switch ground circuit for an open.

  1. Tests the transfer case switch for proper operation.

Step

Action

Values

Yes

No

Schematic Reference:Transfer Case Control Schematics

1

Did you perform a Diagnostic System Check – Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn OFF the ignition.
  2. Disconnect the front axle actuator.
  3. Ensure the 4-wheel drive (4WD) control lever is in the 4WD position.
  4. Turn ON the ignition with the engine OFF.
  5. With a DMM, test the ignition 3 voltage circuit for proper voltage.

Does the voltage measure within the specified value?

9–14 V

Go to Step 3

Go to Step 7

3

  1. Disconnect the front axle actuator.
  2. Turn ON the ignition, with the engine OFF.
  3. With a DMM, measure the voltage between the ignition 3 voltage circuit and the ground circuit at the front axle actuator.

Does the voltage measure within the specified value?

9–14 V

Go to Step 4

Go to Step 8

4

  1. Turn ON the ignition, with the engine OFF.
  2. Shift the transfer case into 4HI.
  3. Connect a test lamp between the ignition 3 voltage circuit and the axle actuator control circuit, at the front axle actuator.

Does the test lamp illuminate?

Go to Step 11

Go to Step 5

5

  1. Disconnect the transfer case switch.
  2. Connect a test lamp from the ignition 3 voltage circuit to the transfer case switch ground circuit

Does the test lamp illuminate?

Go to Step 6

Go to Step 9

6

With the control lever in the 4WD position, test for continuity across the transfer case switch.

Is continuity present across the switch?

Go to Step 10

Go to Step 12

7

Repair the open in the ignition 3 voltage circuit. Refer to Circuit Testing and Wiring Repairs.

Did you complete the repair?

Go to Step 13

8

Repair the open in the ground circuit. Refer to Circuit Testing and Wiring Repairs.

Did you complete the repair?

Go to Step 13

9

Repair the open in the transfer case switch ground circuit. Refer to Circuit Testing and Wiring Repairs.

Did you complete the repair?

Go to Step 13

10

Repair the open in the axle actuator control circuit. Refer to Circuit Testing and Wiring Repairs.

Did you complete the repair?

Go to Step 13

11

Replace the front axle actuator. Refer to Front Drive Axle Actuator Replacement.

Did you complete the replacement?

Go to Step 13

12

Replace the transfer case switch. Refer to Transfer Case Gear Indicator Switch Replacement.

Did you complete the repair?

Go to Step 13

13

Operate the vehicle in order to determine if the symptom has been corrected.

Is the symptom still present?

Go to Step 2

System OK

"Portions of materials contained herein have been reprinted with permission of General Motors Corporation, Service and Parts Operations" License Agreement #0410810.

Copyright 2007 - 2012 Service Repair Solutions, Inc.

Expert:  Reggie Whiddon replied 10 months ago.

9-04-21-001: SERVICE*****MESSAGE - DTC C0387, C0569 SET (REPROGRAM TRANSFER CASE CONTROL MODULE) (MAY 19, 2009)

Subject:Service*****Message - DTC C0387 C0569 Set (Reprogram Transfer Case Control Module)

Models:2009 Cadillac Escalade Hybrid
2007–2009 Chevrolet Avalanche, Silverado, Silverado Hybrid, Suburban, Tahoe, Tahoe Hybrid
2007–2009 GMC Sierra, Sierra Hybrid, Yukon, Yukon Hybrid, Yukon XL
All Equipped with Transfer Case RPO NQF or NQH

Condition

Some customers may comment that the Service*****message is displayed. This may be the result of setting DTC C0387 or DTCs C0387 and C0569. When the code is current, the transfer case system remains inoperative for the rest of the ignition key cycle. For RPO NQF vehicles, both C0387 and C0569 may be set together with or without requesting a transfer case shift. For RPO NQH vehicles, the C0387 may be set when requesting a transfer case mode or range shift. On RPO NQH transfer cases, these DTCs can also be set during normal driving conditions in Auto 4WD, 4HI or 4LO. These DTCs may intermittently set during extreme cold or warm weather, or periods of lower than normal battery charge.

Cause

The Service*****message and the resulting DTC(s) set is a result of the Transfer Case Control Module (TCCM) software not updated to the latest version.

Correction

Important: DO NOT replace the TCCM for this condition.

Reprogram the TCCM with the revised calibration and then perform the Clutch Reset Procedure (Motor Learn Procedure).

Important: If DTC C0387 or DTCs C0387 and/or C0569 occur, check connectors and wiring, and service as necessary prior to reprogramming the TCCM.

Important: A voltage of 10.5 or higher is required to successfully complete the Clutch Reset Procedure without setting DTCs.

  1. Reprogram the TCCM with the latest software calibration.

    Important: Select the correct calibration files for the appropriate vehicle configuration (body style) and RPO codes.

    A revised calibration has been developed to address this condition. Technicians are to reprogram the TCCM using the Service Programming System (SPS) with the latest software available on TIS2WEB. Refer to Transfer Case Shift Control Module Programming and Setup procedures in SI. As always, make sure your Tech 2® is updated with the latest software version.

  2. Perform the Clutch Reset Procedure (Motor Learn Procedure). Refer to Transfer Case High/Low Clutch Reset in SI.
  3. Read and clear all the DTCs.
  4. Perform the following mode and range shifts: 2HI - 4HI, 2HI - 4LO, 2HI - Neutral.
  5. Test drive the vehicle. Use all modes, including 'Auto' mode for RPO NQH vehicles.

Warranty Information

For vehicles repaired under warranty, use:

Labor Operation

Description

Labor Time

K4121

Transfer Case Shift Control Module Reprogramming with SPS

0.4 hr

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

Copyright General Motors Corporation.

Portions of materials contained herein are sourced from General Motors Inc., Co.

Expert:  Reggie Whiddon replied 10 months ago.

Transfer Case Control Module (TCCM)

- Vechicle stuck in*****when it does it locks front diff and is hard to turn on paved roads. Reflased with tech2 per bulletin 09 21 001 and fix it.

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Replaced Transfer Case Control Module (TCCM)6Al Smirnov
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November 17, 20142007 Chevrolet Avalanche, LTZ 5.3L, V8, Flex, VIN 3, Des LC9, USA *
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4Barry Martin
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5Howie Farr
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6Frank Coviello
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7Gerry Schomisch
July 18, 20152009 Chevrolet Silverado 1500, LT 5.3L, V8, Flex, VIN 0, Des LMG, 16V, USA *
Transfer Case Shift Control Module ReprogrammingPerformed Transfer Case Shift Control Module Reprogramming

8Jeff Hovey
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Transfer Case Shift Control Module ReprogrammingPerformed Transfer Case Shift Control Module Reprogramming

9Scott Keyser
June 8, 20152008 Chevrolet Silverado 1500, LT 5.3L, V8, Flex, VIN 3, Des LC9, 16V, USA *
Transfer Case Shift Control Module ReprogrammingPerformed Transfer Case Shift Control Module Reprogramming

10(+) 11-12Chip Mcnichols
April 2, 20152007 Chevrolet Silverado 1500, Classic LT 5.3L, V8, Gas, VIN B, 16V, USA *
Transfer Case Shift Control Module ReprogrammingPerformed Transfer Case Shift Control Module Reprogramming

Expert:  Reggie Whiddon replied 10 months ago.

Hi i am Reggie hope i didnt bomb you with to much info there what i gave you is the test method right out of the factory service manual, and then i included a bulletin that is out addressing the issue your having, and I included couple of pages of failure records with confirmed repairs of vehicles like yours with same complaint. From what your describing i would recommend you get the reflash and clutch pack reset.

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