GM Service Manual Online
For 1990-2009 cars only

Object Number: 155209  Size: SF
ABS Components
Antilock Brake System Schematics
Handling ESD Sensitive Parts Notice
Antilock Brake System Schematics

Circuit Description

DTC C1277 identifies a solenoid that cannot be energized due to a short to voltage in the solenoid driver circuitry. The malfunction can affect ABS operation since the flow of brake fluid to the wheel cylinder cannot be stopped. The unstoppable flow of brake fluid to the wheel cylinder makes ABS operation for that channel impossible.

Conditions for Setting the DTC

DTC C1277 can set only when the brake solenoid valve is commanded on. A malfunction exists if the EBCM/EBTCM detects the left front brake solenoid valve control circuit voltage is not within specifications.

Action Taken When the DTC Sets

    • A malfunction DTC stores.
    • The ABS/TCS disables.
    • The amber ABS/TCS warning indicators turn on.

Conditions for Clearing the DTC

    • The condition responsible for setting the DTC no longer exists and the Scan Tool Clear DTC function is used.
    • 100 drive cycles pass with no DTC detected.

Diagnostic Aids

Use the enhanced diagnostic function of the Scan Tool in order to measure the frequency of the malfunction. Refer to the Scan Tool manual or Scan Tool Diagnostics located in this section for the procedure.

Thoroughly inspect any circuitry that may cause the intermittent complaint for the following conditions:

    • Rubbed-through wire insulation
    • A broken wire inside the insulation
    • Backed out terminals
    • Improper mating
    • Broken locks
    • Improperly formed or damaged terminals
    • Poor terminal-to-wiring connections
    • Physical damage to the wiring harness

Important: Zero the J 39200 test leads before making any resistance measurements.

DTC C1277 LF Solenoid CKT Short to Voltage

Step

Action

Value(s)

Yes

No

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check

2

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the left front solenoid valve connector.
  3. Turn the ignition switch to the RUN position, engine OFF.
  4. Use the J 39200 in order to measure the voltage between the left front brake solenoid valve connector terminal B and ground.

Is any voltage present during this test?

--

Go to Step 8

Go to Step 3

3

  1. Turn the ignition switch to the OFF position.
  2. Use the J 39200 in order to measure the resistance between the left front brake solenoid valve connector terminal A and terminal B.

Is the resistance within the specified range?

2.0-5.0ohms

Go to Step 4

Go to Step 7

4

  1. Disconnect the 24-way EBCM/EBTCM connector C1.
  2. Turn the ignition switch to the RUN position, engine OFF.
  3. Use the J 39200 in order to measure the voltage between the 24-way EBCM/EBTCM harness connector C1 terminal A10 and ground.

Is any voltage present during this test?

--

Go to Step 8

Go to Step 5

5

  1. Turn the ignition switch to the OFF position.
  2. Inspect the left front brake solenoid valve connector for damage. Damage may cause a short to voltage with the left front brake solenoid valve connector connected.
  3. Inspect the 24-way EBCM/EBTCM connector C1 for damage. Damage may cause a short to voltage with the 24-way EBCM/EBTCM connector C1 connected.

Is there damage that may cause a short to voltage?

--

Go to Step 9

Go to Step 6

6

  1. Reconnect the 24-way EBCM/EBTCM connector C1.
  2. Reconnect the left front brake solenoid valve connector.
  3. Release the brake and start the engine.
  4. Allow the engine to run for at least 10 seconds.
  5. Use the Scan Tool in order to inspect for DTCs.

Does DTC C1277 set as a current DTC?

--

Go to Step 10

Go to Step 11

7

Replace the left front brake solenoid valve. Refer to Brake Solenoid Valve Replacement .

Is the repair complete?

--

Go to Diagnostic System Check

--

8

Repair the short to voltage in CKT 826.

Is the repair complete?

--

Go to Diagnostic System Check

--

9

Repair the damage that caused a short to voltage.

Is the repair complete?

--

Go to Diagnostic System Check

--

10

Replace the EBCM/EBTCM. Refer to Electronic Brake and Traction Control Module Replacement .

Is the repair complete?

--

Go to Diagnostic System Check

--

11

The malfunction is intermittent or not present at this time.

Is a concern still present?

--

Go to Diagnostic Aids

Go to Diagnostic System Check