For 1990-2009 cars

### Circuit Description

As the wheel is rotated, the speed sensor produces an AC voltage that increases with wheel speed. The electronic brake control module (EBCM) uses the frequency of the AC signal to calculate the wheel speed. The speed sensor is connected to the EBCM by a twisted pair of wires. Twisting reduces noise susceptibility that may cause a DTC to set.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C1209 Right Rear Wheel Speed Circuit Open or Shorted

### Conditions for Running the DTC

Ignition is in the ON position.

### Conditions for Setting the DTC

EBCM has detected an open, short to ground, or a short to battery on the right rear wheel speed circuit.

### Action Taken When the DTC Sets

• | The solenoid relay opens, removing power from the pump motor and solenoids.

• | DTC C1209 is stored.

• | ABS disabled, ABS warning lamp turns ON.

### Conditions for Clearing the DTC

• | If the conditions that set the DTC C1209 are no longer present, the DTC may be cleared by using the proper scan tool.

• | The DTC that has not occurred in 100 drive cycles will be cleared from history data.

### Diagnostic Aids

Thoroughly inspect the wiring and connectors when diagnosing intermittent DTCs. This will include the following:

• | Removal of the protective conduit and inspection of wiring for damage, shorts, and contamination

• | Inspection for improperly formed and/or damaged terminals

• | Checking terminal contact retention force by using a spare male/female terminal

• | Removal of the terminals from the connectors to check for proper terminal to wire crimp

If the driver comments reflect that the ABS warning lamp is ON only during moist environmental changes, such as, rain, snow, vehicle wash, the all wheel speed sensor circuitry should be thoroughly inspected for signs of water intrusion. If the DTC is not current, simulate the effects of water intrusion. Use the following procedure. Spray the suspected area with a 5 percent salt water solution. Then test drive the vehicle over various road surfaces, such as, bumps, turns, etc., above 24 km/h (15 mph). If the DTC sets then replace the suspected harness and/or sensor.

When measuring the wheel speed sensor resistance, ensure the vehicle is at room temperature, since resistance will increase with temperature.

Failure to perform the previous steps carefully and fully can result in misdiagnosis, unnecessary component replacement, and reoccurrence of DTC C1209.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Turn the ignition switch OFF.
2. Inspect the right rear wheel speed sensor, and/or the jumper harness for physical damage.

Is any physical damage noted?

--

Go to Step 3

Go to Step 4

3 | Repair the damage to the right rear wheel speed sensor, and/or jumper harness. Did you find and correct the condition? | -- | Go to Step 24 | --
4 | Test drive the vehicle at various speeds and over various road surfaces. Did DTC C1209 reset? | -- | Go to Step 5 | Go to Diagnostic Aids
5 |

1. Turn the ignition switch OFF, with the vehicle in park.
2. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle
3. Disconnect the right rear jumper harness from the right rear wheel speed sensor.
4. Connect an ohmmeter to terminals 2 and 1 of the right rear wheel speed sensor.
5. Resistance will vary with temperature.

Is the resistance within the specified range?

800-1600 ohms

Go to Step 7

Go to Step 6

6 | Replace the right rear wheel speed sensor. Refer to Rear Wheel Speed Sensor Replacement . Did you complete the replacement? | -- | Go to Step 24 | --
7 |

1. The right rear jumper harness is still disconnected from the speed sensor.
2. Connect an ohmmeter to terminal 2 of the right rear wheel speed sensor and then to body ground.

Is the resistance equal to the specified value?

OL (open circuit)

Go to Step 8

Go to Step 6

8 |

1. Disconnect the electronic brake control module (EBCM) harness from the EBCM.
2. Disconnect the right rear jumper harness from the ABS body harness.
3. Connect an ohmmeter to the EBCM harness terminal 23 and then to wheel speed sensor terminal 2.

Is the resistance measured less than the specified value?

2 ohms

Go to Step 10

Go to Step 9

9 | Repair the open or high resistance between terminals 23 and 2. Did you find and correct the condition? | -- | Go to Step 24 | --
10 |

1. The EBCM harness is still disconnected from the EBCM.
2. The right rear jumper harness is still disconnected from the body harness.
3. Connect an ohmmeter to the EBCM harness terminal 22 and then to wheel speed sensor terminal 1.

Is the resistance measured less than the specified value?

2 ohms

Go to Step 3

Go to Step 11

11 | Repair the open or high resistance between terminals 22 and 1. Did you find and correct the condition? | -- | Go to Step 24 | --
12 |

1. The EBCM harness is still disconnected from the EBCM.
2. The right rear jumper harness is still disconnected from the ABS body harness.
3. Connect a voltmeter to EBCM harness terminals 23 and then to body ground.

Is the voltage less than the specified value?

1 V

Go to Step 14

Go to Step 13

13 | Repair the short to voltage between terminals 23 and 2. Did you find and correct the condition? | -- | Go to Step 24 | --
14 |

1. The EBCM harness is still disconnected from the EBCM.
2. The right rear jumper harness is still disconnected from the ABS body harness.
3. Connect a voltmeter to the EBCM harness terminal 22 and then to body ground.

Is the voltage less than the specified value?

1 V

Go to Step 16

Go to Step 15

15 | Repair the short to voltage between terminals 22 and 1. Did you find and correct the condition? | -- | Go to Step 24 | --
16 |

1. The EBCM harness is still disconnected from the EBCM.
2. The right rear jumper harness is still disconnected from the ABS body harness.
3. Connect an ohmmeter to the EBCM harness terminal 23 and then to body ground.

Is the resistance measured equal to the specified value?

OL (open circuit)

Go to Step 18

Go to Step 17

17 | Repair the short to ground between terminals 23 and 2. Did you find and correct the condition? | -- | Go to Step 24 | --
18 |

1. The EBCM harness is still disconnected from the EBCM.
2. The right rear jumper harness is still disconnected from the ABS body harness.
3. Connect an ohmmeter to the EBCM harness terminal 22 and then to body ground.
4. Connect an ohmmeter to the EBCM harness terminal 23 and then to body ground.

Is the resistance measured equal to the specified value?

OL (open circuit)

Go to Step 20

Go to Step 19

19 | Repair the short to ground between terminals 22 and 1. Did you find and correct the condition? | -- | Go to Step 24 | --
20 |

1. The EBCM harness is still disconnected from the EBCM.
2. The right rear jumper harness is still disconnected from the ABS body harness.
3. Connect an ohmmeter to the EBCM harness terminal 23 and 22.

Is the resistance measured equal to the specified value?

OL (open circuit)

Go to Step 22

Go to Step 21

21 | Repair the short between the 2 circuits. Did you find and correct the condition? | -- | Go to Step 24 | --
22 |

1. Replace the right rear wheel speed sensor jumper harness.
2. Test drive the vehicle at the various speeds and various road surfaces.

Did the DTC C1209 reset?

--

Go to Step 23

Go to Step 24

23 | Replace the EBCM. Refer to Brake Pressure Modulator Valve Assembly Replacement . Did you complete the replacement? | -- | Go to Step 24 | --
24 |

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