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Home >> Buick >> 2007 >> Lucerne CX >> Repair and Diagnosis >> External Pages >> Different car >> Section 46 (Antilock Brake System, Traction Control System & Stability Control System) >> Diagnostic Information and Procedures >> DTC C0241 or P0856 >> Test Description

Test Description

WARNING: This page is about a different car, the 2005 Buick LaCrosse and 2005 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

  1. 3:  Use the scan tool in order to determine if the requested torque signal has a valid duty cycle.
  2. 4:  Measure the requested torque signal in order to determine if the signal has a valid duty cycle.
  3. 5:  Measure the requested torque signal in order to determine if the signal has a valid frequency.
  4. 11:  This vehicle is equipped with a powertrain control module (PCM) which uses an electrically erasable programmable read only memory (EEPROM). When replacing the PCM, the replacement PCM must be programmed.
DTC C0241 or P0856

Step Action Value(s) Yes No
Schematic Reference: ABS Schematics 
Connector End View Reference: ABS Connector End Views 
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2 Inspect the electronic brake control module (EBCM) ground and powertrain control module (PCM) ground, ensuring each ground is clean and torqued to the proper specification. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 13  Go to Step 3 
3 
  1. Install a scan tool.
  2. Start the engine.
  3. With the scan tool, observe the Torque Request Signal parameter in the Powertrain Control Module data list.
Does the scan tool display less than the specified value?		 100% Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems Go to Step 4 
4 
  1. Turn OFF the ignition.
  2. Disconnect the EBCM harness connector.
  3. Install the J 39700  Universal Breakout Box using the J 39700-530 Cable Adapter to the EBCM harness connector and the EBCM connector. See Special Tools .
  4. Start the engine.
  5. Measure the DC duty cycle between the requested torque signal circuit and a good ground.
Is the duty cycle within the specified range?		 5-95% Go to Step 5  Go to Step 6 
5  Measure the DC Hz between the requested torque signal circuit and a good ground.
Does the frequency measure within the specified range?		 121-134 Hz Go to Step 8  Go to Step 6 
6
  1. Turn OFF the ignition.
  2. Disconnect the cable adapter from the EBCM connector.
    3. IMPORTANT: Disconnecting the EBCM connector and turning ON the ignition could cause other modules to set loss of communication DTCs (Uxxxx). Once the EBCM is reconnected, the EBCM may set DTC C0241.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the requested torque signal circuit to a good ground.
Does the voltage measure within the specified range?		 4-6 V Go to Step 10  Go to Step 7 
7
  1. Turn OFF the ignition.
  2. Disconnect the PCM harness connector.
  3. Test the requested torque signal circuit for the following conditions:
    • A short to voltage
    • A short to ground
Refer to Circuit Testing and Wiring Repairs in Wiring Systems.Did you find and correct the condition?		 - Go to Step 13  Go to Step 10 
8
  1. Turn OFF the ignition.
  2. Disconnect the PCM harness connector.
  3. Test the requested torque signal circuit for the following conditions:
    • An open
    • A high resistance
Refer to Circuit Testing and Wiring Repairs in Wiring Systems.Did you find and correct the condition?		 - Go to Step 13  Go to Step 9 
9 Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 13  Go to Step 11 
10 Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections andConnector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 13  Go to Step 12 
11  Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.
Did you complete the repair?		 - Go to Step 13  -
12 Replace the EBCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.
Did you complete the repair?		 - Go to Step 13  -
13
  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
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