GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2002 🢒 Escalade 🢒 Steering 🢒 Variable Effort Steering 🢒 DTC C0501, C0503, or C0504

Circuit Description

The Body Control Module (BCM), or Electronic Suspension Control (ESC) module, vehicles equipped with Real Time Damping (RTD), provides a return or control circuit to the Electronic Variable Orifice (EVO) solenoid when the ignition is turned ON. This circuit is used by the control module to disable the EVO solenoid outputs when a fault is detected to provide full steering assist.

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

A short to ground, short to voltage, or an open in the EVO solenoid control circuit.

Action Taken When the DTC Sets
    • DTC C0501 will be stored in memory on vehicles W/ RTD.
    • DTC C0503 and C0504 will be stored in memory on vehicles W/O RTD.
    • The EVO solenoid outputs are disabled for the remainder of the ignition cycle.

Conditions for Clearing the DTC
    • A current DTC will clear after the 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 EVO solenoid resistance is with in specified range.

    3.

  3. Tests for poor connections at the EVO solenoid harness connector.

    4.

  4. Tests if the control module is supplying a ground to the EVO solenoid.

    5.

  5. Tests for a short to ground on the EVO solenoid control circuit.

    6.

  6. Program the ESC module/BCM after replacement.

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 from OFF to ON.

Does the EVO solenoid turn OFF and ON 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. Measure the resistance of the EVO solenoid.

Does the resistance measure within the specified value?

11-13ohms

Go to Step 4

Go to Step 11

4

Inspect the EVO solenoid harness connector control and supply circuits for poor connections. 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 13

Go to Step 5

5

  1. Probe the EVO solenoid control circuit at the solenoid harness connector with a test lamp connected to battery voltage.
  2. Turn ON the ignition, with the engine OFF.

Does the test lamp turn ON when the ignition is turned ON?

--

Go to Step 7

Go to Step 6

6

Does the test lamp remain on continuously with the ignition ON or OFF?

--

Go to Step 8

Go to Step 9

7

  1. Turn ON the ignition, with the engine OFF.
  2. With the scan tool, command the EVO solenoid OFF.

Does the test light turn OFF with initial command?

--

Go to Step 13

Go to Step 8

8

Test the EVO solenoid control 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 13

Go to Step 12

9

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

Did you find and correct the condition?

--

Go to Step 13

Go to Step 10

10

Inspect the Suspension Control Module/BCM harness connector control circuit for poor connections. 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 13

Go to Step 12

11

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

Did you complete the replacement?

--

Go to Step 13

--

12

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

Did you complete the replacement?

--

Go to Step 13

--

13
  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