GM Service Manual Online
For 1990-2009 cars only

Object Number: 233696  Size: SF
ABS Components
Antilock Brake System Schematics

Circuit Description

DTC C1276 identifies a brake solenoid valve that cannot be energized. The malfunction may be caused by one of the following conditions:

    • An open in the solenoid valve circuitry.
    • The solenoid valve is always energized due to a short to voltage in the solenoid valve circuitry between the EBCM and the brake solenoid valve.

An open will not allow proper ABS operation, but the short to voltage simply turns ON the brake solenoid valve. A path for base brakes is still allowed once the motor rehomes and the check ball is lifted off its seat during key to ON initialization.

Conditions for Setting the DTC

This DTC will set when the following conditions are met:

    • The EBCM detects a short to voltage or open in CKT 9I01 and/or open in CKT 9V01.
    • This DTC can be set only when the solenoid is OFF.

Action Taken When the DTC Sets

    • A malfunction DTC stores.
    • The ABS disables.
    • The ABS warning indicator turns 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.
    • 100 drive cycles pass with no DTCs detected. A drive cycle consists of starting the vehicle, driving the vehicle over 16 km/h (10 mph), stopping and then turning the ignition off.

Diagnostic Aids

The following conditions may cause an intermittent malfunction:

    • A poor connection
    • Rubbed-through wire insulation
    • A broken wire inside the insulation

Use the enhanced diagnostic function of the Scan Tool in order to measure the frequency of the malfunction.

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

    • 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. Refer to the J 39200 user's manual.

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 LOCK.
  2. Disconnect the EBCM connector C1.
  3. Disconnect LF ABS solenoid electrical connector.
  4. Turn ignition switch to ON.
  5. Use the J 39200 in order to measure the voltage between the EBCM harness connector C1 terminal D14 and ground.

Is the voltage within the range specified in the Value(s) column?

0.0-2.0 V

Go to Step 3

Go to Step 7

3

Use the J 39200 in order to measure the resistance between the EBCM harness connector C1 terminal D14 and the LF ABS solenoid valve harness connector terminal A.

Is the resistance within the range specified in the Value(s) column?

0.0-2.0 ohms

Go to Step 4

Go to Step 8

4

Use the J 39200 in order to measure the resistance between the LF ABS solenoid connector terminal B and ground.

Is the resistance within the range specified in the Value(s) column?

0.0-2.0 ohms

Go to Step 5

Go to Step 9

5

Use the J 39200 in order to measure the resistance between the LF ABS solenoid terminals A and B.

Is the resistance within the range specified in the Value(s) column?

2.5-5.0 ohms

Go to Step 6

Go to Step 10

6

  1. Inspect the LF ABS solenoid and connectors for poor terminal contact and corrosion.
  2. Inspect CKT 9I01 for damage which may result in a short to voltage with all connectors connected.
  3. Reconnect all connectors.
  4. Start the engine.
  5. Drive vehicle at 16 km/h (10 mph) for 10 seconds.
  6. Stop vehicle and turn ignition switch to LOCK.
  7. Repeat drive cycle (steps 4, 5 and 6 above).
  8. Turn ignition switch to ON.
  9. Use the Scan Tool in order to inspect for DTCs.

Did DTC C1276 set in the past three ignition cycles?

--

Go to Step 11

Go to Diagnostic System Check

7

Repair the short to voltage in CKT 9I01.

Is the repair complete?

--

Go to Diagnostic System Check

--

8

Repair open or high resistance in CKT 9I01.

Is the repair complete?

--

Go to Diagnostic System Check

--

9

  1. Repair open or high resistance in CKT 9V01.
  2. Check for a tight, clean G105.

Is the repair complete?

--

Go to Diagnostic System Check

--

10

Replace the LF ABS solenoid. Refer to Brake Solenoid Valve Replacement

Is the repair complete?

--

Go to Diagnostic System Check

--

11

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

Is the repair complete?

--

Go to Diagnostic System Check

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