For 1990-2009 cars
ABS Components
Antilock Brake System Schematics

### Circuit Description

The Electronic Brake Control Module (EBCM) receives a voltage signal from the left rear wheel speed sensor through terminals 8 and 14. As a toothed reluctor wheel ring passes by the wheel speed sensor, changes in the electromagnetic field cause the wheel speed sensor to produce a small AC voltage signal. This signal's frequency is proportional to the wheel speed.

### Conditions for Setting the DTC

• | DTC C0045 will set when the EBCM detects an open, a short to voltage, or a short to ground in CKT 884 or CKT 885.

• | DTC C0045 can be set anytime.

### Action Taken When the DTC Sets

• | A malfunction DTC stores.

• | The ABS disables.

• | The ABS warning indicator turns ON.

### Conditions for Clearing the DTC

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

### Diagnostic Aids

Inspect for the following when diagnosing this part of the Antilock Brake System (ABS):

• | Faulty electrical circuits between the left rear wheel speed sensor and the EBCM. These faults include the following:

- | Open and or high resistance

- | Short to voltage

- | Short to ground

• | Faulty left rear wheel speed sensor (out of range resistance).

An intermittent malfunction is most likely caused by a poor connection, rubbed thorough wire insulation, or by a wire that is broken inside the insulation.

If the ABS indicator lamp is ON only during humid conditions (rain, snow, vehicle wash), thoroughly inspect the left rear wheel speed sensor circuitry for signs of water intrusion.

Thoroughly inspect any 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

### Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

1. The Diagnostic System Check must be the starting point for any ABS related diagnosis.

2. Tests for wheel speed sensor internal resistance for proper values.

3. Tests for wheel speed sensor circuits shorted together.

4. Tests for a short to ground in CKT 885.

5. Tests for a short to ground in CKT 884.

6. Tests for a short to voltage in CKT 885.

7. Tests for a short to voltage in CKT 884.

8. Tests for an open or high resistance in CKT 885.

9. Tests for an open or high resistance in CKT 884.

10. Tests for a poor connections at electrical connectors.

11. Determines whether the condition is intermittent and not due to a faulty EBCM.

Important: Wheel speed sensor resistance increases with an increase in sensor temperature.

When measuring for a short to ground in a wheel speed sensor wiring circuit manually switch to J 39200 (Digital Multimeter) to the Meg-Ohms range. This will ensure a high resistance short to ground can be found. See J 39200 owners manual.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Diagnostic System Check performed? | -- | Go to Step 2 | Go to Diagnostic System Check
2 |

1. Raise and suitable support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
2. Disconnect the left rear wheel speed sensor electrical connector.
3. Use J 39200 DMM in order to measure the resistance between the left rear wheel speed sensor connector terminal A and terminal B (sensor side).

Is the resistance within the range specified in the Value(s) column?

840-2030 ohms

Go to Step 3

Go to Step 12

3 |

1. Disconnect the Electronic Brake Control Module (EBCM) electrical connector.
2. Use J 39200 DMM in order to measure the resistance between the left rear wheel speed sensor connector terminal A and terminal B (harness side).

Is the resistance equal to the value specified in the Value(s) column?

OL

(Infinite)

Go to Step 4

Go to Step 13

4 | Use J 39200 DMM in order to measure the resistance between the left rear wheel speed sensor connector terminal A (harness side) and ground. Is the resistance equal to the value specified in the Value(s) column? | OL (Infinite) | Go to Step 5 | Go to Step 14
5 | Use J 39200 DMM in order to measure the resistance between the left rear wheel speed sensor connector terminal B (harness side) and ground. Is the resistance equal to the value specified in the Value(s) column? | OL (Infinite) | Go to Step 6 | Go to Step 15
6 |

1. Turn the ignition switch to the ON position.
2. Use J 39200 DMM in order to measure the voltage between the left rear wheel speed sensor connector terminal A (harness side) and ground.

Is the voltage within the range specified in the Value(s) column?

0-1 V

Go to Step 7

Go to Step 16

7 | Use J 39200 DMM in order to measure the voltage between the left rear wheel speed sensor connector terminal B (harness side) and ground. Is the voltage within the range specified in the Value(s) column? | 0-1 V | Go to Step 8 | Go to Step 17
8 | Use J 39200 DMM in order to measure the resistance between the left rear wheel speed sensor connector terminal A (harness side) and the EBCM electrical connector terminal 8 (harness side). Is the resistance within the range specified in the Value(s) column? | 0-2 ohms | Go to Step 9 | Go to Step 18
9 | Use J 39200 DMM in order to measure the resistance between the left rear wheel speed sensor connector terminal B (harness side) and the EBCM electrical connector terminal 14 (harness side). Is the resistance within the range specified in the Value(s) column? | 0-2 ohms | Go to Step 10 | Go to Step 19
10 |

1. Inspect the EBCM electrical connector and the left rear wheel speed sensor connector for the following conditions:

• | Poor terminal contact

• | Corrosion

• | Damage

2. Repair as necessary.

Is the action complete?

--

Go to Step 11

--

11 |

1. Turn the ignition switch to the LOCK position.
2. Reconnect the left rear wheel speed sensor electrical connector.
3. Reconnect the EBCM electrical connector.
4. Turn the ignition switch to the ON position.
5. Connect a scan tool to the Data Link Connector (DLC).
6. Select Diagnostic Trouble Codes (DTC) on the scan tool.
7. Select DTC Information on the scan tool.
8. Select Current DTC on the scan tool.

Is DTC C0045 set as a Current DTC?

--

Go to Step 21

Go to Step 20

12 | Replace the left rear wheel speed sensor. Refer to On-Vehicle Service for Wheel Speed Sensor Replacement procedures. Is the repair complete? | -- | Go to Diagnostic System Check | --
13 | Repair the short between CKT 884 and CKT 885. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Diagnostic System Check | --
14 | Repair short to ground in CKT 885. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Diagnostic System Check | --
15 | Repair short to ground in CKT 884. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Diagnostic System Check | --
16 | Repair short to voltage in CKT 885. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Diagnostic System Check | --
17 | Repair short to voltage in CKT 884. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Diagnostic System Check | --
18 | Repair an open or high resistance in CKT 885. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Diagnostic System Check | --
19 | Repair an open or high resistance in CKT 884. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Diagnostic System Check | --
20 | A malfunction is not present at this time. Refer to Diagnostic Aids for additional information regarding this DTC. Is action complete? | -- | Go to Diagnostic System Check | --
21 |

1. Test the electrical harness between the Electronic Brake Control Module (EBCM) and the left rear wheel speed sensor for possible short to ground, short to voltage, or open in CKT 884 and/or CKT 885.
2. Inspect the EBCM electrical connector for poor terminal contact.
3. Repair wiring as necessary. Refer to Wiring Repairs in Wiring Systems.
4. If the wiring is OK, replace the brake pressure modulator valve assembly. Refer to Brake Pressure Modulator Valve Assembly Replacement .

Is the repair complete?

--

Go to Diagnostic System Check

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