C0056

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Part 2 Of 2:

CIRCUIT DESCRIPTION
The speed sensor used on this vehicle is a single point magnetic pickup. This sensor produces an AC signal that the Electronic Brake Control Module (EBCM) uses the frequency from to calculate the wheel speed.

CONDITIONS FOR SETTING THE DTC
^ The Diagnostic Trouble Code (DTC) will set if one wheel speed = 0 and the other Wheel Speed Sensors (WSS) are greater than 40 Km/h (25 mph) for 10 ms, or if the Electronic Brake Control Module (EBCM) detects a short to ground.
^ The DTC will set if during drive off, one wheel speed = 0, and the other WSS are greater than 12 Km/h (7.5 mph).

ACTION TAKEN WHEN THE DTC SETS
^ A malfunction Diagnostic Trouble Code (DTC) stores.
^ The Antilock Brake System (ABS) disables.
^ The amber ABS indicator turns on.
^ The Red BRAKE Warning indicator turns on.

CONDITIONS FOR CLEARING THE DTC
^ The condition responsible for setting the Diagnostic Trouble Code (DTC) no longer exists and the Scan tool Clear DTCs function is used.
^ 100 ignition cycles pass with no DTC(s) detected.

IMPORTANT: After the DTC is cleared by ignition cycle default, the vehicle must be driven above 12 Km/h (8 mph) for the Antilock Brake System/Traction Control System (ABS/TCS) indicator(s) to turn off.

DIAGNOSTIC AIDS
^ It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.
^ Thoroughly inspect any circuitry that may be causing the 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

^ The following conditions may cause an intermittent malfunction:
- A poor connection
- Rubbed-through wire insulation
- A broken wire inside the insulation

^ If the customer's comments reflect that the amber Antilock Brake System (ABS) indicator is on only during moist environmental conditions (rain, snow, vehicle wash), inspect all the Wheel Speed Sensor (WSS) circuitry for signs of water intrusion. If the Diagnostic Trouble Code (DTC) is not current, clear all DTCs and simulate the effects of water intrusion by using the following procedure:
1. Spray the suspected area with a five percent saltwater solution. Add two teaspoons of salt to twelve ounces of water to make a five percent saltwater solution.
2. Test drive the vehicle over various road surfaces (bumps, turns, etc.) above 40 Km/h (25 mph) for at least 30 seconds.
3. If the DTC returns, replace the suspected harness.

^ If an intermittent malfunction exists refer to Troubleshooting Procedures Cell 4 in Diagnostic Aids for further diagnosis.

REAR WHEEL SPEED SENSOR RESISTANCE
The table shown contains resistance values for the rear Wheel Speed Sensors (WSS) at varying sensor temperatures for use in diagnosis. The values are approximate and should be used as a guideline for diagnosis.





DTC C0056 REAR WHEEL SPEED CKT RANGE/PERFORMANCE

TEST DESCRIPTION
The number(s) below refer to the step number(s) on the diagnostic table.
6. This step checks for the proper resistance in the Wheel Speed Sensor (WSS).
7. This step checks for the proper WSS output.