GM Service Manual Online
For 1990-2009 cars only

Circuit Description

This circuit is used to monitor the voltage level available to the electronic brake control module (EBCM) . If the voltage rises above a certain level, damage to the system may occur.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C1101 Battery Voltage High

Conditions for Running the DTC

Vehicle speed is greater than 8 km/h (5 mph)

Conditions for Setting the DTC

Ignition voltage to terminal 9 and/or 25 is greater than 17 volts for 1 second.

Action Taken When the DTC Sets

    • The solenoid relay opens, removing voltage from the solenoids and pump motor.
    • DTC C1101 is stored.
    • ABS is disabled, ABS warning lamp turns ON.

Conditions for Clearing the DTC

    • If the conditions that set the DTC C1101 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

Typical causes for DTC C1101 to set:

    • Charging system malfunction
    • Poor connection
    • EBCM malfunction

Step

Action

Values

Yes

No

Schematic Reference: Antilock Brake System Schematics

Connector End View Reference: Antilock Brake System Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Disconnect the electronic brake control module (EBCM) connector.
  2. Turn ON the ignition.
  3. Check the voltage between terminal 4 and 8 of the EBCM connector.
  4. Check the voltage between terminal 4 and 24 of the EBCM connector.

Were the voltages within the specified range?

9.4-17 V

Go to Step 3

Go to Step 4

3

Replace the EBCM. Refer to Brake Pressure Modulator Valve Assembly Replacement .

Did you find any problem?

--

Go to Step 12

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4

Check the battery voltage between terminal (+) and (-) of the battery.

Is the voltage within the specified value?

9.4-17 V

Go to Step 6

Go to Step 5

5

Replace the battery.

Did you complete the replacement

--

Go to Step 12

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6

Check the resistance between terminal 4 of the EBCM connector and the terminal (+) of the battery.

Is the resistance less than specified?

1 ohms

Go to Step 8

Go to Step 7

7

  1. Check both the terminals mentioned in step 6.
  2. Repair the terminals, as needed.
  3. Check the EBCM connector and wiring harness.
  4. Repair or replace the wiring harness as needed.

Did you find and correct the condition?

--

Go to Step 12

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8

Check the resistance between the terminal 8, 24, and G105.

Does the resistance measure less than the specified value?

1 ohms

Go to Step 10

Go to Step 9

9

Repair or replace the EBCM connector or G105.

Did you complete the repair?

--

Go to Step 12

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10

  1. Connect a voltmeter to the positive and negative terminal of the battery.
  2. Turn OFF all accessories.
  3. Start the engine.
  4. Monitor the voltage on the meter with the engine running at 2,000 RPM for several seconds.
  5. And also check the voltage between the terminal 4 and 8. And also check the voltage between the terminal 4 and 24.

Do the voltages measure less than the specified value?

17 V

Go to Step 12

Go to Step 11

11

Repair the alternator.

Did you complete the repair?

--

Go to Step 12

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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 the DTC reset?

 

Go to Step 2

System OK