For 1990-2009 cars
Steering Controls Components
Steering Assist Schematics
Handling ESD Sensitive Parts Notice

### Circuit Description

The EBCM connector terminals supply a 5.0-volt reference to the steering wheel speed sensors. The sensors provide steering wheel speed input signals as follows:

• | The EBCM terminal 1 supplies signals to sensor A.

• | The EBCM terminal 17 supplies signals to sensor B.

• | The EBCM terminal 5 provides the steering wheel speed sensor ground.

### Conditions for Setting the DTC

• | The DTC C1243 can set anytime.

• | A malfunction exists if the steering wheel speed sensor voltage is less than 0.4 volts or greater than 4.7 volts.

• | The DTC C1243 sets if the steering wheel speed sensor voltage changes by more than 2.0 volts within 8.0 milliseconds.

### Action Taken When the DTC Sets

• | A malfunction DTC is stored.

• | The VES is disabled and power steering returns to full assist.

• | The ABS remains functional.

### Conditions for Clearing the DTC

Clearing VES DTCs automatically clears ABS DTCs resulting in a loss of DTC history data. Refer to Diagnostic Aids.

### Diagnostic Aids

The steering wheel speed sensor is malfunctioning. Verify the frequency of the malfunction by using the enhanced diagnostic function of the scan tool. Refer to Enhanced Diagnostics in ABS/ETS.

An open or short in any of the sensor signal circuit wires exists. An intermittent malfunction is most likely caused by one of the following conditions:

• | A poorly connected wire

• | A wire that has rubbed through the insulation

• | A wire that is broken inside the insulation

• | A backed out terminal

• | An improper mating

• | A broken lock

• | An improperly formed or damaged terminal

• | A poor terminal to wiring connection

• | A sign of physical damage to the wiring harness

When diagnosing for an intermittent short or an open, massage the wiring harness while watching the test equipment for changes.

Conditions for clearing the DTC are as follows:

• | All ABS DTCs have been diagnosed and corrected.

• | Conditions for the malfunction are no longer present.

• | The CLEAR function on a scan tool has been used.

• | 100 drive cycles have passed with no malfunctions detected. A drive cycle consists of the following conditions:

• | Starting the vehicle.

• | Driving the vehicle over 16 km/h (10 mph).

• | Stopping the vehicle.

• | Turning the ignition off.

#### DTC C1243

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the ABS Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check
2 | Is DTC C1243 current? | -- | Go to Step 3 | Refer to Diagnostic Aids
3 |

1. Start the engine.
2. Install a scan tool.
3. Select the ABS DATA LIST.
4. Monitor the steering wheel sensor voltage while you rotate the steering wheel from stop-to-stop.

Is the voltage within the specified range?

0.4-4.7 V

Go to Step 4

Go to Step 6

4 | Continue to monitor the steering wheel speed sensor voltage while you rotate the steering wheel from stop-to-stop. Is the voltage within the specified range? | 0.4-4.7 V | Go to Step 5 | Go to Step 10
5 | Problem is intermittent. Refer to Diagnostic Aids. Did you complete the diagnosis? | -- | Go to Diagnostic System Check | --
6 | Continue to monitor the steering wheel sensor voltage while you rotate the steering wheel from stop-to-stop. Is the voltage below the specified value? | 0.4 V | Go to Step 7 | Go to Step 12
7 |

1. Disconnect the steering wheel sensor.
2. Turn OFF the ignition switch.
3. Use J 39200 in order to measure the voltage on the harness connector side between the steering sensor connector terminal A and ground.

Is the voltage within the specified range?

4.5-5.5 V

Go to Step 8

Go to Step 14

8 | Use J 39200 in order to measure the voltage between the wiring harness sensor connector terminals A and B. Is the voltage within the specified range? | 4.5-5.5 V | Go to Step 9 | Go to Step 15
9 | Replace the steering wheel speed sensor. Refer to Steering Wheel Position Sensor or Steering Shaft Lower Bearing Replacement . Is the repair complete? | -- | Go to Step 18 | --
10 |

1. Disconnect the steering wheel speed sensor.
2. Turn OFF the ignition switch.
3. Use J 39200 in order to measure the resistance on the connector sensor side between the steering sensor connector terminals A and B.
4. Turn the steering wheel slowly from stop to stop.

Is the resistance within the specified range?

390-12,000 ohms

Go to Step 11

Go to Step 9

11 | Inspect the following circuits for poor connections, opens, or shorts:

• | CKT 1056

• | CKT 1059

• | CKT 556

Did you find a problem in one or more of these circuits?

--

Go to Step 17

Go to Step 16

12 |

1. Disconnect the steering wheel sensor connector.
2. Turn the ignition switch to the RUN position.

Does the scan tool display the steering wheel sensor voltage greater than the specified value?

4.7 V

Go to Step 13

Go to Step 9

13 | Inspect CKT 1059 for a short to voltage. Did you find a short to voltage in CKT 1059? | -- | Go to Step 17 | Go to Step 16
14 | Inspect CKT 1056 for an open or a short to ground. Did you find an open or a short to ground in CKT 1056? | -- | Go to Step 17 | Go to Step 16
15 | Inspect CKT 1059 for an open or a short to ground. Did you find an open or a short to ground in CKT 1059? | -- | Go to Step 17 | Go to Step 16
16 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement in Antilock brake System. Did you complete the repair? | -- | Go to Step 18 | --
17 | Repair the problems found with the following circuits:

• | CKT 1056

• | CKT 1059

• | CKT 556

Did you complete the repair?

--

Go to Step 18

--

18 |

1. Reconnect all connectors.
2. Clear all EBCM codes.
3. Verify that the repair is complete.

Does the system operate properly?

--

Go to Diagnostic System Check

--