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 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.
Conditions for Setting the DTC
DTC C0034 can be set anytime the key is ON and the EBCM has detected an open, a short to ground, or a short to battery on the left rear wheel speed circuit.
Action Taken When the DTC Sets
| • | The solenoid relay opens, removing power to the pump motor and solenoids. |
| • | DTC C0034 is stored. |
| • | The antilock brake system (ABS) is disabled. The ABS warning lamp turns ON. |
Conditions for Clearing the DTC
| • | If the conditions that set DTC C0034 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 to wiring for damage, shorts, and contamination |
| • | Inspection for improperly formed and/or damaged terminals |
| • | Inspecting terminal contact, retention force, by using a spare male/female terminal |
| • | Removal of the terminals from the connectors to inspect for proper terminal to wire crimp |
If the drivers comments reflect that the ABS warning lamp is ON only during moist environmental changes, such as rain, snow, vehicle wash, etc., 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.
- 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 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 C0034.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Perform the Diagnostic System Check-ABS. Did you find the problem? | -- | Go to Step 2 | |
2 |
Is any physical damage noted? | -- | Go to Step 3 | Go to Step 4 |
3 | Repair the damage to the left rear wheel speed sensor, jumper harness, and/or toothed ring. Is the repair complete? | -- | System OK | -- |
4 | Test-drive the vehicle at various speeds and over various road surfaces. Did DTC C0034 reset? | -- | Go to Step 6 | Go to Step 5 |
5 | DTC C0034 is intermittent. Refer to Diagnostic Aids. | -- | System OK | -- |
6 |
Important: The resistance will vary with temperature. Is the resistance within the specified range? | 800-1,600 ohms | Go to Step 8 | Go to Step 7 |
7 | Replace the left rear wheel speed sensor. Is the replacement complete? | -- | System OK | -- |
8 |
Does the resistance measure OL, open circuit? | -- | Go to Step 9 | Go to Step 7 |
9 |
Is the resistance less than the specified value? | 2 ohms | Go to Step 11 | Go to Step 10 |
10 | Repair the open or high resistance between terminals A3 and 2. Is the repair complete? | -- | System OK | -- |
11 |
Is the resistance less than the specified value? | 2 ohms | Go to Step 3 | Go to Step 12 |
12 | Repair the open or high resistance between terminals A4 and 1. Is the repair complete? | -- | System OK | -- |
13 |
Is the voltage less than the specified value? | 1 V | Go to Step 15 | Go to Step 14 |
14 | Repair the short to voltage between terminals A3 and 2. Is the repair complete? | -- | System OK | -- |
15 |
Is the voltage less than the specified value? | 1 V | Go to Step 17 | Go to Step 16 |
16 | Repair the short to voltage between terminals A4 and 1. Is the repair complete? | -- | System OK | -- |
17 |
Does the resistance measure OL, open circuit? | -- | Go to Step 19 | Go to Step 18 |
18 | Repair the short to ground between terminals A3 and 2. Is the repair complete? | -- | System OK | -- |
19 |
Does the resistance measure OL, open circuit? | -- | Go to Step 21 | Go to Step 20 |
20 | Repair the short to ground between terminals A4 and 1. Is the repair complete? | -- | System OK | -- |
21 |
Does the resistance measure OL, open circuit? | -- | Go to Step 23 | Go to Step 22 |
22 | Repair the short between the 2 circuits. Is the repair complete? | -- | System OK | -- |
23 |
Did DTC C0034 reset? | -- | Go to Step 23 | System OK |
24 | Replace the EBCM. Is the replacement complete? | -- | System OK | -- |
