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Home >> Buick >> 2007 >> Lucerne CX >> Repair and Diagnosis >> External Pages >> Different car >> Section 216 (Antilock Brake System With 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 2006 Pontiac Montana SV6, 2006 Chevrolet Uplander, and 2006 Buick Terraza. 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. 4:  This step tests for voltage supplied to the EBCM from the PCM.
  2. 5:  This step tests for a shorted resistor in the PCM or a short to voltage within the requested torque signal circuit by verifying that a large voltage drop occurs when a test lamp is connected in parallel with the DMM.
DTC C0241 or P0856

Step Action Values Yes No
Schematic Reference: ABS Schematics 
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2 Is DTC P0856 set? - Go to Step 3  Go to Diagnostic Aids
3
  1. Use a scan tool in order to clear the DTCs.
  2. Start the engine.
  3. Does DTC P0856 set?
 - Go to Step 4  Go to Diagnostic Aids
4 
  1. Turn OFF the ignition.
  2. Disconnect from the electronic brake control module (EBCM), the harness connector containing the requested torque signal circuit.
  3. Turn ON the ignition.
  4. Use a DMM to measure the voltage between the requested torque signal circuit and a good ground.
Does the voltage measure greater than the specified value?		 4.75 V Go to Step 5  Go to Step 6 
5 
  1. With the DMM still connected to monitor the requested torque signal circuit, connect one end of a test lamp to a good ground.
  2. Connect the other end of the test lamp to the positive lead of the DMM.
Does the voltage measure less than the specified value?		 0.15 V Go to Step 9  Go to Step 7 
6 Test the requested torque signal circuit for an open or a short to ground. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 12  Go to Step 8 
7 Test the requested torque signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 12  Go to Step 10 
8 Inspect for poor connections at the harness connector of the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 12  Go to Step 10 
9 Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 12  Go to Step 11 
10 Replace the PCM. Refer to Control Module References for replacement, setup and programming.
Did you complete the replacement?		 - Go to Step 12  -
11 Replace the EBCM. Refer to Control Module References for replacement, setup and programming.
Did you complete the replacement?		 - Go to Step 12  -
12
  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 DTC P0856 reset?		 - Go to Step 4  System OK
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