GM Service Manual Online
For 1990-2009 cars only

Object Number: 406529  Size: LF
ABS Components
Cell 44: Stoplamp/BTSI Switch, Inlet/Outlet Solenoid Valves, and Wheel Speed Sensors
Cell 10: TURN LPS, FLAT PACK MTR, PERIM LP, and ABS Fuses
Cell 10: ABS PUMP MOTOR, ABS MAIN, and COOLING FAN Fuses
Cell 14: G102, G104, G106, G110 and G301
Cell 14: G202 (1 of 3) (Buick)
Cell 14: G202 (1 of 3) (Oldsmobile)
Handling ESD Sensitive Parts Notice

Circuit Description

The normally closed outlet valves operate similarly to the inlet valves. When the EBCM/EBTCM grounds an outlet valve, however, the valve opens instead of closes.

The EBCM/EBTCM opens an outlet valve for short periods in order to reduce pressure at the LR wheel.

Conditions for Setting the DTC

The DTC C1256 sets when the EBCM/EBTCM detects an open or short to ground in the LR outlet valve circuit.

Action Taken When the DTC Sets

The following actions are taken when the DTC sets:

    • A malfunction DTC is stored.
    • The ABS is disabled.
    • The ANTILOCK indicator lamp is turned ON.

Conditions for Clearing the DTC

The DTC will clear under following conditions:

    • Conditions for the malfunction are no longer present. Use the scan tool Clear DTCs function.
    • 100 ignition switch key cycles have passed without detecting any malfunctions

Diagnostic Aids

Perform a thorough inspection of the wiring and the connectors.

Failure to inspect wiring carefully may result in a misdiagnosis. A misdiagnosis may result in replacing parts without repairing the malfunction.

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 BPMV connector C1.
  3. Use the J 39200 in order to measure the resistance between the BPMV connector C1 terminals 13 and 14.

Is the resistance less than the specified value?

2 ohms

Go to Step  3

Go to Step  13

3

Measure the resistance between the BPMV connector C1 terminal 14 and the BPMV assembly block.

Is the resistance equal to the specified value?

OL (Infinite)

Go to Step  4

Go to Step  13

4

Measure the resistance between the BPMV connector C1 terminals 14 and 10.

Is the resistance within the specified range?

3-6 ohms

Go to Step  5

Go to Step  13

5

  1. Disconnect the EBCM/EBTCM connector.
  2. Install the J 38716 pinout box.
  3. Measure the resistance between the J 38716 pinout box terminal 36 and the BPMV harness connector terminal 10.

Is the resistance less than the specified value?

2 ohms

Go to Step  6

Go to Step  9

6

  1. Reconnect the BPMV harness connector C1.
  2. Measure the resistance between the J 38716 pinout box terminal 1 and the ground.

Is the resistance less than the specified value?

2 ohms

Go to Step  7

Go to Step  10

7

  1. Disconnect the ABS main relay.
  2. Measure the resistance between the J 38716 pinout box terminal 1 and the EBCM/EBTCM harness connector terminal 36.

Is the resistance equal to the specified value?

OL (Infinite)

Go to Step  8

Go to Step  11

8

  1. Reinstall the ABS main relay.
  2. Turn the ignition switch to the RUN position.
  3. Use the J 39200 in order to measure the voltage between the J 38716 pinout box terminal 1 the EBCM/EBTCM harness connector terminal 36.

Is the voltage greater than the specified value?

1 V

Go to Step  12

Go to Step  14

9

Repair the open or high resistance in CKT 1291. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Diagnostic System Check

--

10

Repair the open or high resistance in CKT 1451. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Diagnostic System Check

--

11

Repair the short to ground in CKT 1291. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Diagnostic System Check

--

12

Repair the short to voltage in CKT 1291. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Diagnostic System Check

--

13

Replace the BPMV. Refer to Brake Pressure Modulator Valve Replacement .

Is the repair complete?

--

Go to Diagnostic System Check

--

14

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

Is the repair complete?

--

Go to Diagnostic System Check

--