GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2004 🢒 GTO 🢒 DTC 🢒 DTC 85

Circuit Description

This circuit monitors the voltage level available to the electronic brake control module (EBCM).

Conditions for Running the DTC

DTC 85 can be set anytime the ignition switch is in the ON position.

Conditions for Setting the DTC

The EBCM detects voltage is below 10 volts.

Action Taken When the DTC Sets
    • The EBCM disables the antilock brake and traction control systems for the duration of the ignition cycle.
    • The ABS and TRAC OFF warning indicators turn ON.

Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists and the Scan Tool Clear DTCs function is used.

Diagnostic Aids

Thoroughly inspect the wiring and the connectors. An incomplete inspection of the wiring and the connectors may result in a misdiagnosis, causing a part replacement with the reappearance of the malfunction.

The following are possible causes of the malfunction:

    • An open, high resistance or short to ground in the EBCM ignition voltage circuit
    • An internal EBCM malfunction

If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

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

  1. This step tests the UART SEC circuit of the EBCM for an open, high resistance, short to ground or short to voltage.

Step

Action

Value(s)

Yes

No

Schematic Reference: Antilock Brake System Schematics

Connector End View Reference: Antilock Brake System Connector End Views

1

Did you perform A Diagnostic System Check - ABS?

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Go to Step 2

Go to Diagnostic System Check - ABS

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine running.
  3. With the scan tool, observe the battery voltage in the ABS data list.
  4. Operate the vehicle within the Condition for Running the DTC as specified in the supporting text.

Does the scan tool indicate the battery voltage is as specified?

Above 10 V

Go to Diagnostic Aids

Go to Step 3

3

Measure battery voltage at the battery terminals.

Does the battery voltage measure as specified?

At least 10 V

Go to Step 4

Go to Charging System Test in Engine Electrical

4
  1. Turn OFF the ignition.
  2. Disconnect the electronic brake control module (EBCM) harness connector.
  3. Turn On the ignition.
  4. Measure the voltage between the ignition positive voltage circuit and a good ground. Refer to Circuit Testing in Wiring Systems.

Does the battery voltage measure as specified?

At least 10 V

Go to Step 5

Go to Step 6

5

Inspect for poor connections at the harness connector of the EBCM. 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 8

Go to Step 7

6

Test the ignition positive voltage circuit for an open, high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 8

--

7

Replace the EBCM. Refer to Electronic Brake Control Module Replacement .

Did you complete the replacement?

--

Go to Step 8

--

8
  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