GM Service Manual Online
For 1990-2009 cars only

Object Number: 155209  Size: SF
ABS Components
Antilock Brake System Schematics

Circuit Description

DTC 1276 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 ground in the solenoid valve circuitry between the driver and the brake solenoid valve.

An open will not allow proper ABS operation but the short to ground 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 RUN initialization.

Conditions for Setting the DTC

DTC C1276 can set only when the brake solenoid valve is commanded off while the Electronic Brake Control Relay is enabled. 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 C1276 LF Solenoid CKT Open/Short to Ground

Step

Action

Value(s)

Yes

No

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2

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

Is continuity to ground present during this test?

--

Go to Step 12

Go to Step 3

3

  1. Disconnect the left front brake solenoid valve connector.
  2. Use the J 39200 in order to measure the resistance between the 24-way EBCM/EBTCM harness connector C1 terminal A10 and the left front brake solenoid valve harness connector terminal B.

Is the resistance within the specified range?

0.0-2.0ohms

Go to Step 4

Go to Step 14

4

Use the J 39200 in order to measure the resistance between the left front ABS brake solenoid valve connector terminal A and the left front brake solenoid valve connector terminal B.

Is the resistance within the specified range?

2.0-5.0ohms

Go to Step 5

Go to Step 15

5

Use a J 39200 in order to measure the resistance between the electronic brake control relay harness connector terminal A2 and the left front brake solenoid valve connector terminal A.

Is the resistance within the specified range?

0.0-2.0ohms

Go to Step 6

Go to Step 9

6

  1. Inspect the 24-way EBCM/EBTCM connector C1 and the 24-way EBCM/EBTCM harness connector C1 for the following conditions:
  2. • Terminal damage
    • Poor terminal contact
    • Terminal corrosion
  3. Inspect the left front brake solenoid valve connector and the right front brake solenoid valve harness connector for the following conditions:
  4. • Terminal damage
    • Poor terminal contact
    • Terminal corrosion

Are terminal corrosion, damaged terminals, or poor terminal contact evident?

--

Go to Step 16

Go to Step 7

7

Inspect CKT 826 for damage. Damage which may cause a short to ground when the connectors are connected.

Is there damage that may cause a short to ground with the connectors connected?

--

Go to Step 17

Go to Step 8

8

  1. Reconnect the 24-way EBCM/EBTCM connector C1.
  2. Reconnect the left front brake solenoid valve connector.
  3. Turn the ignition switch to the RUN position, engine OFF.
  4. Use the Scan Tool in order to inspect for DTCs.

Does DTC C1276 set as a current DTC?

--

Go to Step 20

Go to Step 21

9

Remove and inspect the ABS/SOL Fuse (20A) from the fuse block.

Is the fuse OK?

--

Go to Step 10

Go to Step 18

10

Use the J 39200 in order to measure the resistance between the electronic brake control relay harness connector terminal A2 and the fuse block terminal G1.

Is the resistance within the specified range?

0.0-2.0ohms

Go to Step 11

Go to Step 19

11

Repair the open in CKT 855.

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

12

  1. Disconnect the left front brake solenoid valve connector.
  2. Use the J 39200 in order to measure the resistance between the left front brake solenoid valve connector terminal B and ground.

Is continuity to ground present during this test?

--

Go to Step 13

Go to Step 15

13

Repair the short to ground in CKT 826.

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

14

Repair the open or high resistance in CKT 826.

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

15

Replace the left front brake solenoid valve.

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

16

Replace all the terminals and connectors that exhibit the following conditions:

    • Poor terminal contact
    • Terminal corrosion
    • Damaged terminals

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

17

Repair the damage to CKT 826.

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

18

Repair the short to ground in CKT 855.

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

19

Repair the open or high resistance in CKT 1633.

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

20

Replace the EBCM/EBTCM.

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

21

The malfunction is intermittent or not present at this time.

Is a concern still present?

--

Go to Diagnostic Aids

Go to Diagnostic System Check - ABS