C0305 Explained

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C0305 Explained

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Blazer >> Mechanical & Maintenance >> Do-It-Yourself >> C0305 Explained

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C0305 Explained - 3/10/2008 8:47:51 AM

swartlkk

Posts: 14530
Joined: 5/1/2005
From: Waterloo, NY
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C0305

NVG 236/246-NP8 Two-Speed Automatic

Circuit Description
The Front Propshaft Speed Sensor is a Permanent Magnet (PM) generator. The PM generator produces a pulsing AC voltage. The AC voltage level and number of pulses increases as speed increases. The transfer case shift control module converts the pulsating AC voltage to a propshaft RPM which is used for calculations, and to monitor the difference between the front and rear propshaft speed. It is also used in the AUTO 4WD mode of operation to determine the amount of slip and the percent of torque to apply to the front axle. The module only looks at this input when the vehicle is in AUTO 4WD mode, 4H, and 4L ranges. The propshaft RPM can be displayed with a scan tool.
This DTC detects an open, short to ground, short to voltage or faulty sensor.

Conditions for Setting the DTC
The system will log the DTC if the front propshaft input indicates a speed of less than 16 RPM for 30 seconds while all of the following are true:

   * Transmission is NOT in Park/Neutral
   * Engine is running
   * Front axle is engaged
   * Vehicle Speed On Class 2 Data bus exceeds 10 mph

Action Taken When the DTC Sets

   * All Shifts to AUTO 4WD mode will be disabled. If the current mode is AUTO 4WD, the system will not allow any further adaptive events (correct wheel slip).
   * 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.

2. Tests to see if the malfunction is intermittent.
3. Tests the internal resistance of the propshaft speed sensor.
4. Tests to see if the propshaft speed sensor can generate a sufficient amount of AC voltage.
5. Tests the FSS LO circuit for a short to ground, a high resistance, or an open.
6. Tests the FSS HI circuit for a short to ground, a high resistance, or an open.
7. Tests the FSS LO circuit for a short to voltage.
8. Tests the FSS HI circuit for a short to voltage.
9. Tests the FSS LO circuit for a short to the FSS HI circuit.

NVG 136-NP4 (One Speed Automatic)