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

### Circuit Description

A 5.0 volt reference is supplied to the steering wheel position sensor through the EBCM connector terminal 1 to sensor terminal A. Steering wheel position input to the EBCM is provided through steering wheel position sensor terminal B to the EBCM terminal 17. Steering wheel position sensor ground is provided through the EBCM terminal 5.

### Conditions for Setting the DTC

• | DTC C1243 can set anytime.

• | Steering wheel position sensor voltage is less than 0.4 volts or greater than 4.7 volts for 2 seconds or longer.

• | Steering wheel position sensor voltage changes by more than 2.5 volts within 8.0 milliseconds.

### Action Taken When the DTC Sets

• | A malfunction DTC stores.

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

• | ABS remains functional.

### Conditions for Clearing the DTC

• | The condition responsible for setting the DTC no longer exists and the Scan Tool Clear DTCs function is used.

• | 100 drive cycles pass with no DTCs detected. A drive cycle consists of starting the vehicle, driving the vehicle over 16 km/h (10 mph), stopping and then turning the ignition OFF.

### Diagnostic Aids

The following conditions may cause an intermittent malfunction:

• | A poor connection

• | Rubbed-through wire insulation

• | A broken wire inside the insulation

• | Open or short in any of the sensor signal circuit wires

• | Malfunctioning steering wheel position sensor

Use the Snapshot function of the Scan Tool to aid in monitoring steering wheel position sensor voltages.

Use the enhanced diagnostic function of the Scan Tool in order to measure the frequency of the malfunction.

Thoroughly inspect any circuitry that may be causing the intermittent complaint for the following conditions:

• | Backed out terminals

• | Improper mating

• | Broken locks

• | Improperly formed or damaged terminals

• | Poor terminal-to-wiring connections

• | Physical damage to the wiring harness

Ensure all ABS DTCs are diagnosed and corrected prior to clearing VES DTCs. Clearing VES DTCs will automatically clear ABS DTCs resulting in a loss of DTC history data.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
Important: Zero the J 39200 test leads before making any resistance measurements. Refer to the J 39200 user's manual. Important: Difficulty may occur when trying to locate intermittent malfunctions in the steering wheel position sensor circuit. Do not disturb any of the electrical connections. Change the electrical connections only when instructed to do so by a step in the diagnostic table.
1 | Was the ABS Diagnostic System Check performed? | -- | Go to Step 2 | Go to Diagnostic System Check - ABS
2 |

1. Start the engine.
2. Using a scan tool, select DATA DISPLAY.
3. Select VES DATA.
4. Monitor the steering wheel sensor voltage while rotating the steering wheel from stop-to-stop.

Does the voltage vary within the specified range?

0.4-4.7 V

Go to Step 43

Go to Step 3

3 | Is the voltage from Step 2 less than the specified value? | 0.4 V | Go to Step 5 | Go to Step 4
4 | Is the voltage from Step 2 greater than the specified value? | 4.7 V | Go to Step 14 | Go to Step 21
5 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the steering wheel position sensor.
3. Disconnect the EBCM harness connector.
4. Using the J 39200 , measure the resistance between the EBCM harness connector terminals 17 and 5.

Is the resistance within the specified range?

OL

(Infinite)

Go to Step 6

Go to Step 29

6 | Using the J 39200 , measure the resistance between the EBCM harness connector terminals 1 and 5. Is the resistance within the specified range? | OL (Infinite) | Go to Step 7 | Go to Step 30
7 | Using the J 39200 , measure the resistance between the EBCM harness connector terminal 17 and ground. Is the resistance within the specified range? | OL (Infinite) | Go to Step 8 | Go to Step 31
8 | Using the J 39200 , measure the resistance between the EBCM harness connector terminal 1 and ground. Is the resistance within the specified range? | OL (Infinite) | Go to Step 9 | Go to Step 32
9 | Using the J 39200 , measure the resistance between the EBCM harness connector terminal 1 and the steering wheel position sensor harness connector terminal A. Is the resistance within the specified range? | 0-2 ohms | Go to Step 10 | Go to Step 33
10 | Using the J 39200 , measure the resistance between the EBCM harness connector terminal 17 and the steering wheel position sensor harness connector terminal B. Is the resistance within the specified range? | 0-2 ohms | Go to Step 11 | Go to Step 34
11 | Inspect EBCM harness connector terminals 1 and 17 and all the steering wheel position sensor terminals for poor terminal contact. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Is poor terminal contact evident? | -- | Go to Step 35 | Go to Step 12
12 |

1. Reconnect the EBCM harness connector.
2. Turn the ignition switch to the ON position.
3. Using the J 39200 , measure the voltage between the steering wheel position sensor harness connector terminals A and C.

Is the voltage greater than the specified value?

4.0 V

Go to Step 41

Go to Step 13

13 |

1. Turn the ignition switch to the OFF position.
2. Inspect CKTs 1056, 1059 and 556 for damage which may result in shorts between the circuits or shorts to ground. Repair damage if present.
3. Reconnect all connectors.
4. Turn the ignition switch to the ON position.

Is DTC C1243 set as a current DTC?

--

Go to Step 42

Go to Diagnostic System Check - ABS

14 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the steering wheel position sensor.
3. Turn the ignition switch to the ON position.

Does the scan tool display the steering wheel position sensor voltage within the specified range?

0-1.0 V

Go to Step 15

Go to Step 16

15 | Using the J 39200 measure the resistance between the steering wheel position sensor harness connector terminal C and ground. Is the resistance within the specified range? | 0-5.0 ohms | Go to Step 41 | Go to Step 18
16 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the EBCM harness connector.
3. Turn the ignition switch to the ON position.
4. Using the J 39200 , measure the voltage between the EBCM harness connector terminal 17 and ground.

Is the voltage within the specified range?

0-1.0 V

Go to Step 17

Go to Step 38

17 |

1. Turn the ignition switch to the OFF position.
2. Inspect CKT 1059 for damage which may result in a short to voltage with all of the connectors connected.

Repair damage if evident.

3. Reconnect all connectors.
4. Turn the ignition switch to the ON position.

Is DTC C1243 set as a current DTC?

--

Go to Step 42

Go to Diagnostic System Check - ABS

18 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the EBCM harness connector.
3. Using the J 39200 , measure the resistance between the steering wheel position sensor harness connector terminal C and the EBCM harness connector terminal 5.

Is the resistance within the specified range?

0-2.0 ohms

Go to Step 19

Go to Step 36

19 |

1. Turn the ignition switch to the ON position.
2. Using the J 39200 , measure the voltage between the EBCM harness connector terminal 5 and ground.

Is the voltage within the specified range?

0-1.0 V

Go to Step 20

Go to Step 37

20 |

1. Turn the ignition switch to the OFF position.
2. Inspect the EBCM harness connector and the steering wheel position sensor terminals for poor terminal contact. Replace any terminals with poor terminal contact.
3. Inspect all the steering wheel position sensor circuits for damage which may result in a short to voltage or an open with all the connectors connected. Repair damage if present.
4. Reconnect all the connectors.
5. Turn the ignition switch to the ON position

Is DTC C1243 set as a current DTC?

--

Go to Step 42

Go to Diagnostic System Check - ABS

21 |

1. Turn the ignition switch to the ON position.
2. With the steering wheel position sensor connected, use the J 39200 in order to measure the voltage between the steering wheel position sensor harness connector terminals A and C by backprobing the connector.

Is the voltage greater than the specified value?

4.7 V

Go to Step 22

Go to Step 23

22 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the steering wheel position sensor.
3. Turn the ignition switch to the ON position.
4. Using the J 39200 , measure the resistance between the steering wheel position sensor harness connector terminals A and C.

Is the voltage greater than the specified value?

4.7 V

Go to Step 27

Go to Step 41

23 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the EBCM harness connector.
3. Disconnect the steering wheel position sensor harness connector.
4. Using the J 39200 , measure the resistance between the EBCM harness connector terminals 1 and 17.

Is the resistance within the specified range?

OL

(Infinite)

Go to Step 24

Go to Step 40

24 | Using the MIN/MAX function of the J 39200 , measure the resistance between the steering wheel position sensor terminals A and B while rotating the steering wheel slowly from stop-to-stop. Is the resistance within the specified range? | 390-12,000 ohms | Go to Step 25 | Go to Step 41
25 |

1. Inspect CKTs 1056 and 1059 for damage which may result in a short between the two circuits with all the connectors connected. Repair damage if present.
2. Reconnect all connectors.
3. Being very careful not to move the steering wheel, turn the ignition switch to the ON position.

Is DTC C1243 set as a current DTC?

--

Go to Step 42

Go to Step 26

26 | Turn the steering wheel slowly from stop-to-stop. Is DTC C1243 set as a current DTC? | -- | Go to Step 41 | Go to Diagnostic System Check - ABS
27 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the EBCM harness connector.
3. Turn the ignition switch to the ON position.
4. Using the J 39200 , measure the voltage between the EBCM harness connector terminal 1 and ground.

Is the voltage greater than the specified voltage?

1.0 V

Go to Step 39

Go to Step 28

28 |

1. Turn the ignition switch to the OFF position.
2. Inspect CKT 1056 for damage which may result in a short to voltage with all the connectors connected. Repair damage if present.
3. Reconnect all the connectors.
4. Turn the ignition switch to the ON position.

Is DTC C1243 set as a current DTC?

--

Go to Step 42

Go to Diagnostic System Check - ABS

29 | Repair the short between CKTs 1059 and 556. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
30 | Repair the short between CKTs 1056 and 556. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
31 | Repair the short to ground in CKT 1059. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
32 | Repair the short to ground in CKT 1056. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
33 | Repair the open or high resistance in CKT 1056. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
34 | Repair the open or high resistance in CKT 1059. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
35 | Replace the terminals that exhibit poor contact. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
36 | Repair the open or high resistance in CKT 556. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
37 | Repair the short to voltage in CKT 556. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
38 | Repair the short to voltage in CKT 1059. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
39 | Repair the short to voltage in CKT 1056. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
40 | Repair the short between CKTs 1056 and 1059. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
41 | Replace the Steering Wheel Position Sensor. Refer to Steering Wheel Position Sensor or Steering Shaft Lower Bearing Replacement . Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
42 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement in Brakes. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
43 | The malfunction is intermittent or not present at this time. Refer to Diagnostic Aids for more information. Is the action complete? | -- | System OK | --