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HOMESERVICE MANUALSCHEVROLET2006COBALT SS, 4D SEDAN, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 281 (ANTILOCK BRAKE SYSTEM WITH TRACTION CONTROL SYSTEM & STABILITY CONTROL SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESDTC C0870TEST DESCRIPTION
2006 Chevrolet Cobalt SS, 4D Sedan, Standard

Test Description

2006 Chevrolet Cobalt SS, 4D Sedan, StandardSECTION Test Description
WARNING: This page is about a different car, the 2006 Buick LaCrosse and 2006 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. 2:  This step tests for specified voltage on the brake pressure signal circuit.
  2. 3:  This step checks to see if the brake pressure signal circuit voltage was below specified voltage.
  3. 4:  This step checks to see if the brake pressure signal circuit voltage was above specified voltage.
  4. 5:  This step tests for a short to ground in the 5-volt reference circuit of the brake pressure sensor.
  5. 6:  This step tests for a short to voltage in the 5-volt reference circuit of the brake pressure sensor.
  6. 7:  This step tests for a high resistance or an open in the ground circuit of the brake pressure sensor.
  7. 8:  This step checks the brake pressure sensor connector for poor connections.
  8. 9:  This step checks the EBCM connector for poor connections.
DTC C0870

Step Action Values 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
2 
  1. Turn OFF the ignition.
  2. Disconnect the electronic brake control module (EBCM).
  3. Install the J 39700  Universal Pinout Box with the J 39700-530  Cable Adapter between the EBCM and the EBCM harness connector. See Special Tools .
  4. Turn ON the ignition, with the engine OFF.
  5. Using the DMM, measure the voltage between pin 17 and pin 15 of the J 39700  . See Special Tools .
Is the voltage within the specified value?		 4.4-5.6 V Go to Diagnostic Aids Go to Step 3 
3 
  1. Turn OFF the ignition.
  2. Disconnect the brake pressure sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. Using the DMM, measure the voltage between pin 17 and pin 15 of the J 39700  . See Special Tools .
Is the voltage greater than the specified value?		 4.4 V Go to Step 4  Go to Step 5 
4  Using the DMM, measure the voltage between pin 17 and pin 15 of the J 39700  . See Special Tools .
Is the voltage less than the specified value?		 5.6 V Go to Step 8  Go to Step 6 
5  Test the 5-volt reference circuit of the brake pressure sensor for 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 9 
6  Test the 5-volt reference circuit of the brake pressure sensor 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 7 
7  Test the ground circuit of the brake pressure sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 12  Go to Step 9 
8  Inspect for poor connections at the harness connector of the brake pressure sensor. 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 brake pressure sensor. Refer to Brake Fluid Pressure Sensor Replacement .
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 test.
Does the DTC reset?		 - Go to Step 2  System OK
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.