No 4WD with CO308 code

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No 4WD with CO308 code

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Blazer Forums >> Mechanical & Maintenance >> Steering, Suspension & Drivetrain >> No 4WD with CO308 code

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No 4WD with CO308 code - 12/9/2007 9:58:10 AM

1blkblazer422

Posts: 31
Joined: 12/9/2007
Status: offline

I have no 4wd in my 2001 blazer. The switch will not light up in any of the 4 functions. I have scanned it with a Tech 2 and got a C0308 Motor A/B circuit low code. Any ideas? Thanks

Post #: 1

RE: No 4WD with CO308 code - 12/9/2007 11:39:55 AM

Chevy Lover

General Tech Moderator
Posts: 3411
Joined: 6/11/2006
From: Vancouver. B.C. Canada
Status: offline

I can not find a transfer case code C0308. From what I read it sounds like you have a code 3.
The first thing to check is your ATC fuse. If it is good, remove it for a minute and re-install it, then check your 4WD functions.

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(in reply to 1blkblazer422)

Post #: 2

RE: No 4WD with CO308 code - 12/9/2007 12:02:02 PM

swartlkk

Posts: 15276
Joined: 5/1/2005
From: Waterloo, NY
Status: offline

I am assuming this is an Automatic 4wd optioned truck.

quote:

C0308

NVG 236/246-NP8 Two-Speed Automatic

Circuit Description
The transfer case motor is a bidirectional, permanent magnet, D.C. motor. When energized, (through Motor Feed A or Motor Feed B. the ground is provided by the opposing Motor Feed circuit and then grounded through the transfer case shift control module ground circuit), the motor, through a series of gears, rotates the sector shaft which moves the mode and range forks to shift the transfer case between 4H, AUTO 4WD, 2H, N. and 4L ranges. While the transfer case motor is energized the transfer case shift control module also energizes the solenoid for the transfer case lock. The motor lock is disabled (locking action released) and free turning of the transfer case motor and sector shaft is then allowed.
This DTC detects a short to ground in Motor Feed A or Motor Feed B CKT.

Conditions for Setting the DTC

   * The system will test the motor circuits:
   * First, the system checks for unwanted voltage.
   * Then, the system supplies voltage on one circuit and reads the voltage back on the other.
   * If the system detects a problem with the circuits, the DTC is logged.
   * The transfer case shift control module senses a low voltage return in Motor Feed A or Motor Feed B when a high voltage is expected.

Action Taken When the DTC Sets

   * All shifting will be disabled.
   * The SERVICE indicator (4WD/AWD) lamp will be latched on for the remainder of the current ignition cycle.

Conditions for Clearing the DTC

   * The transfer case shift control module will clear the DTC if the condition for setting the DTC no longer exists.
   * A history DTC will clear after 100 consecutive ignition cycles without a fault present.
   * History DTCs can be cleared using a scan tool.



Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
Listen for an audible motor noise when the encoder motor operates. Command both the ON and OFF states. Repeat the commands as necessary.

3. Tests for a short to ground in the Motor Feed A circuit.
4. Tests for a short to ground in the Motor Feed B circuit.
5. Tests for a higher than normal resistance in the Motor Feed A and B circuits through the module.
6. Tests for a short to ground in the encoder motor windings.
7. Tests for continuity across the motor circuit. Resistance readings vary depending on the location of the brush contact inside the motor assembly.
8. Tests Motor Feed A circuit for a short to ground.
9. Tests Motor Feed B circuit for a short to ground.
10. Tests Motor Feed A and B circuits for an open or high resistance.