GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2002 🢒 Yukon XL - 2WD 🢒 Steering 🢒 Variable Effort Steering 🢒 DTC C0496, C0498, or C0499

Circuit Description

The Body Control Module (BCM), or Electronic Suspension Control (ESC) module, vehicles equipped with Real Time Damping (RTD), provides a pulse width modulated (PWM) supply circuit to the Electronic Variable Orifice (EVO) solenoid. The supply circuit is used to control the current to the EVO solenoid which regulates the size of the Power steering pump output fluid orifice. This causes an increase or decrease in steering effort depending on vehicle speed.

NOTE: The BCM/ESC stores the DTCs scan tool data and special functions. However, the scan tool menu to access variable effort steering is located in chassis.

Conditions for Running the DTC

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

EVO solenoid command greater than 5 percent PWM duty cycle.

Conditions for Setting the DTC

EVO output PWM greater than 5 percent duty cycle and EVO feed back voltage is less than battery voltage minus 4.0 volts.

Action Taken When the DTC Sets
    • DTC C0496 will be stored in memory on vehicles equipped W/ RTD.
    • DTC C0498 and C0499 will be stored in memory on vehicles W/O RTD.
    • The EVO outputs will be disabled for the remainder of the ignition cycle.

Conditions for Clearing the MIL/DTC
    • A current DTC will clear when malfunction is no longer present.
    • A history DTC will clear after 100 consecutive malfunction free ignition cycles.
    • Using the scan tool

Test Description

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

  1. Tests the EVO solenoid circuits in there active state using the scan tool.

    2.

  2. Tests if the BCM/ESC module is providing voltage to the EVO solenoid.

    3.

  3. Tests for an open in the control circuit to the EVO solenoid.

    4.

  4. Tests if voltage is constantly being applied to the EVO solenoid.

    5.

  5. Reprogram the BCM/ESC module when replacement is necessary.

Step

Action

Value(s)

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, command the EVO solenoid ON and OFF.

Does the EVO solenoid turn ON and OFF with each command?

--

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the EVO solenoid.
  3. Turn ON the ignition, with the engine OFF.
  4. With a test lamp connected to a ground probe the EVO solenoid supply circuit at the solenoid harness connector.
  5. With a scan tool, command the EVO solenoid ON.

Does the test lamp turn ON with initial command?

--

Go to Step 4

Go to Step 5

4

  1. Connect a test lamp between the EVO solenoid supply circuit and the EVO solenoid control circuit of the solenoid harness connector.
  2. With a scan tool, command the EVO solenoid ON.

Does the test lamp turn ON with initial command?

--

Go to Step 8

Go to Step 10

5

Does the test lamp remain illuminated continuously with each command?

--

Go to Step 7

Go to Step 6

6

Test the EVO solenoid supply 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 14

Go to Step 9

7

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

Did you find and correct the condition?

--

Go to Step 14

Go to Step 9

8

Inspect for poor connections at the harness connector of the EVO solenoid . Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 11

9

Inspect for poor connections at the harness connector of the BCM/suspension control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 13

10

Repair the control circuit of the EVO solenoid. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 14

--

11

Measure the resistance of the EVO solenoid.

Does the resistance measure within the specified value?

11-13 ohms

Go to Step 13

Go to Step 12

12

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

Did you complete the replacement?

--

Go to Step 14

--

13

Replace the BCM/ESC module. Refer to Body Control Module Replacement in Body Control Systems, or Electronic Suspension Control Module Replacement in Real Time Damping.

Did you complete the replacement?

--

Go to Step 14

--

14
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK