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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2001 🢒 Yukon - 2WD 🢒 Steering 🢒 Variable Effort Steering 🢒 DTC C0495

DTC C0495 W/O RTD

Circuit Description

The body control module supplies a pulse width modulated (PWM) voltage to the Electronic Variable Orifice (EVO) solenoid as well as a low reference path. The PWM voltage is used to control the current into the solenoid which controls the size of the output orifice of the power steering pump. This results in an increase or decrease in steering wheel turning effort. The body control module is constantly adjusting the PWM voltage and monitoring the current flow to achieve the desired PWM. The system uses inputs from VSS and the steering wheel position/speed sensor for the desired PWM output. This provides the vehicle speed related steering assist.

Conditions for Running the DTC

Vehicle speed greater than 8 km/h (5 mph).

EVO solenoid command greater than 5% PWM duty cycle.

Conditions for Setting the DTC
    • EVO output PWM less than 10% duty cycle and EVO output current greater than 260 mA. or
    • EVO output PWM greater than 94% duty cycle and EVO output current less than or equal to 360 mA.

Action Taken When the DTC Sets
    • DTC C0495 will be stored in memory.
    • The body control module will turn off both EVO solenoid outputs for the remainder of the ignition cycle.

Conditions for Clearing the MIL/DTC
    • A history DTC will clear after not seeing the malfunction for 100 consecutive ignition cycles.
    • Using a scan tool to

Diagnostic Aids
    • Perform a visual inspection for loose or poor connections at all related components.
    • Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Important: 

   • An EVO solenoid that is out of resistance range may cause this DTC to set. Normal resistance of the EVO solenoid is from 11 to 13 ohms.
   • Low vehicle speed = high level of assist.
   • High vehicle speed = low level of assist.
   • EVO is controlled by the body control module on vehicles without the Z55 RPO option. Vehicles with the Z55 RPO option utilize the suspension control module to control the EVO.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. Tests whether the condition is module, system, or condition related.

    2.

  2. Tests the resistance of the EVO solenoid.

    3.

  3. Tests the EVO circuits.

    4.

  4. Clear DTCs and check if the DTC resets.

Step

Action

Yes

No

Schematic Reference: Steering Assist Schematics

1

Did you perform the Variable Effort Steering Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Variable Effort Steering

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, monitor the DTC Information for DTC C0495 in the Body Control Module.

Does the scan tool indicate that DTC C0495 is current?

Go to Step 4

Go to Step 3

3

Since most occurrences of this DTC are caused by the EVO solenoid, review the Variable Effort Steering System or, verify the conditions with the customer under which the DTC set.

Did vehicle operation cause this DTC to set?

Go to Diagnostic Aids

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect connector C1 of the body control module.
  3. Measure the resistance from the EVO solenoid control circuit of the EVO solenoid to the solenoid low reference circuit of the EVO solenoid.

Does the resistance measure between 11 and 13 ohms?

Go to Step 5

Go to Step 5

5

Test the EVO solenoid supply voltage circuit and the solenoid low reference circuit of the EVO solenoid for an open or a short. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 6

--

6

Replace the EVO solenoid Refer to Power Steering Solenoid Actuator and Discharge Fitting Replacement

Did you complete the replacement?

Go to Step 7

--

7

  1. Reconnect all previously disconnected components.
  2. Turn ON the ignition with the engine OFF.
  3. Use the scan tool in order to clear the DTCs.
  4. With the scan tool, command the EVO solenoid from 0% to 100% for 1 minute.

Does the DTC reset?

Go to Step 8

System OK

8
  1. Replace the body control module (BCM). Refer to Body Control Module Replacement in Body Control System.
  2. Program the BCM with the proper calibrations. Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System.
  3. Perform the learn procedure.

Did you complete the replacement?

System OK

--

DTC C0495 W/RTD

Circuit Description

The suspension control module supplies a pulse width modulated (PWM) voltage to the Electronic Variable Orifice (EVO) solenoid as well as a low reference path. The PWM voltage is used to control the current into the solenoid which controls the size of the output orifice of the power steering pump. This results in an increase or decrease in steering wheel turning effort. The suspension control module is constantly adjusting the PWM voltage and monitoring the current flow to achieve the desired PWM. The system uses inputs from VSS and the steering wheel position/speed sensor for the desired PWM output. This provides the vehicle speed related steering assist.

Conditions for Running the DTC

Vehicle speed greater than 8 km/h (5 mph).

EVO solenoid command greater than 5% PWM duty cycle.

Conditions for Setting the DTC
    • EVO output PWM less than 10% duty cycle and EVO output current greater than 260 mA. or
    • EVO output PWM greater than 94% duty cycle and EVO output current less than or equal to 360 mA.

Action Taken When the DTC Sets
    • DTC C0495 will be stored in memory.
    • The suspension control module will turn off both EVO solenoid outputs for the remainder of the ignition cycle.

Conditions for Clearing the MIL/DTC
    • A history DTC will clear after not seeing the malfunction for 100 consecutive ignition cycles.
    • Using a scan tool

Diagnostic Aids

       Important: If DTC C0496 and/or DTC C0501 are present, perform the diagnosis for these DTC's before proceeding.

    • Check connectors at the EVO solenoid, Suspension Control Module and all in-line connectors for proper seating and that terminals are clean and tight.
    • A EVO solenoid that is out of resistance range may cause this DTC to set. Normal resistance of the EVO solenoid is from 11 to 13 ohms.
    • Low vehicle speed = high level of assist.
    • High vehicle speed = low level of assist.
    • EVO is controlled by the suspension control module with the Z55 RPO option only. Vehicles without the Z55 option, EVO is controlled by the Body Control Module (BCM).

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. Tests whether the condition is module, system, or condition related.

  2. Tests whether the EVO solenoid and circuits.

    3.

  3. Test the EVO circuits.

  4. Clear DTCs and check if the DTC resets.

Step

Action

Yes

No

Schematic Reference: Steering Assist Schematics

1

Did you perform the RTD Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Real Time Damping

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, monitor the DTC Information for DTC C0495 in the Suspension Control Module.

Important: If DTC C0496 and/or DTC C0501 are present, perform the diagnosis for these DTC's before proceeding.

Does the scan tool indicate that DTC C0495 is current?

Go to Step 4

Go to Step 3

3

Since most occurrences of this DTC are caused by EVO solenoid, review the RTD System or, with the customer to verify the conditions under which the DTC set.

Did vehicle operation cause this DTC to set?

Go to Diagnostic Aids

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect connector C2 of the suspension control module.
  3. Measure the resistance from the EVO solenoid supply voltage circuit of the EVO solenoid to the solenoid low reference circuit of the EVO solenoid.

Does the resistance measure between 11 and 13 ohms?

Go to Step 5

Go to Step 5

5

Test the EVO solenoid supply voltage circuit and the solenoid low reference circuit of the EVO solenoid for an open and a short.

Refer to Circuit Testing , Testing for Short to Ground and Testing for a Short to Voltage .

Did you find and correct the condition?

Go to Step 7

Go to Step 6

6

Replace the EVO solenoid Refer to Power Steering Solenoid Actuator and Discharge Fitting Replacement

Did you complete the replacement?

Go to Step 7

--

7

  1. Reconnect all previously disconnected components.
  2. Turn ON the ignition, with the engine OFF.
  3. Use the scan tool in order to clear the DTCs.
  4. With the scan tool, command the EVO solenoid ON and OFF for 1 minute.

Does the DTC reset?

Go to Step 8

System OK

8

Important: Perform the set up procedure for the suspension control module when replacement is necessary.

Replace the suspension Control Module. Refer to Electronic Suspension Control Module Replacement .

Did you complete the replacement?

System OK

--