GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Corvette 🢒 Brakes 🢒 Antilock Brake System 🢒 DTC C1241

Circuit Description

The variable effort steering (VES) system uses the electronic brake control module (EBCM) to control current to a bi-directional electromagnetic rotary actuator. The EBCM commands current from negative 2 amps to positive 3 amps to the actuator. At low speeds, a negative current is commanded, which assists steering. At medium speeds, no current is commanded and steering is assisted by hydraulics only. At high speeds, a positive current is commanded, which creates steering resistance.

Conditions for running the DTC
    • Ignition voltage between 10.5 and 17 volts
    • Off state test - Initial ignition ON, no engine rpm or vehicle speed present.
    • On state test - If off state test passes, engine rpm and vehicle speed present.

Conditions for Setting the DTC

An open, short to ground, or short to voltage in the VES actuator or the circuits to the actuator.

Action Taken When the DTC Sets
    • A DTC C1241 is stored in memory.
    • The DIC may display the SERVICE STEERING SYS warning message.
    • The VES system is disabled.

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

Diagnostic Aids

The vehicle needs to be driven to view full commanded and feedback current ranges on the scan tool.

Test Description

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

  1. Tests if the Commanded and Feedback Current parameters are at the specified value in there active state.

    2.

  2. Tests if the resistance of the VES actuator is in the specified range.

    3.

  3. Tests the high effort control circuit for an open or short to voltage.

    4.

  4. Tests the low effort control circuit for a short to ground.

    5.

  5. Tests for poor connections at the VES actuator harness connector.

    6.

  6. Perform the setup procedure after EBCM replacement.

Step

Action

Value(s)

Yes

No

Schematic Reference: Steering Assist Schematics

Connector End View Reference: Steering Assist Connector End Views

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. Start the engine.
  3. With the scan tool, observe the Magna Steer Commanded Current and the Magna Steer Feedback Current Data parameters in the Magna Steer data list.

Does the scan tool indicate that the Magna Steer Commanded and Magna Steer Feedback Current parameters are within .05 amps of each other and within specified range?

-1.84 to -1.99 A

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 VES actuator harness connector.
  3. Measure the resistance of the VES actuator.

Does the resistance measure within the specified range?

1.6-3.1 ohms

Go to Step 4

Go to Step 10

4

Test the VES actuator and actuator harness for a short to ground. Refer to Testing for Short to Ground and to Wiring Repairs in Wiring Systems.

Was a short to ground located?

--

Go to Step 5

Go to Step 6

5

Visually inspect the actuator harness for any cut, chaffed or damaged wires.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 12

6

Test the high effort control circuit of the VES actuator 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 7

7

Test the high effort control circuit of the VES actuator for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 8

8

Test the low effort control circuit of the VES actuator 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

9

Test the low effort control circuit of the VES actuator for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 11

10

Inspect for poor connections at the harness connector of the VES actuator. 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 12

11

Inspect for poor connections at the harness connector of the EBCM. 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

12

Replace the VES actuator. Refer to Steering Gear Replacement in Power Steering System.

Did you complete the repair?

--

Go to Step 14

--

13

Important: Perform the setup procedure for the EBCM. An unprogrammed EBCM will result in the following conditions:

   • Inoperative, or poorly functioning DRP/ABS/TCS/VSES/VES/TPM system, if equipped.
   • Set DTC C1248
   • Set DTC C1255

Replace the EBCM. Refer to Electronic Brake Control Module Replacement in Antilock Brake System.

Did you complete the repair?

--

Go to Step 14

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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