GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2000 🢒 LeSabre 🢒 Brakes 🢒 Antilock Brake System 🢒 DTC C1236 Low System Supply Voltage

Object Number: 456417 Size: MF
ABS Components
PWR, GND, Stoplamp Switch, Solenoid Valves, and Pump Motor
Handling ESD Sensitive Parts Notice
Battery Feed to the Rear Fuse Block
Battery Feed to the Underhood Fuse Block
Serial Data Class 2

Circuit Description

The electronic brake control module (EBCM) monitors the voltage level available for system operation. A low voltage condition prevents the system from operating properly.

Conditions for Running the DTC
    • The vehicle speed is greater than 8 km/h (5 mph).
    • The ignition voltage is less than 10.5 volts.
    • The system relay is commanded ON.

Conditions for Setting the DTC

One of the following conditions exists for 0.72 seconds:

    • During initialization or when the system is inactive, the system voltage is less than 10.5 volts.
    • During the system operation, the system voltage is less than 9.0 volts.

Action Taken When the DTC Sets

If equipped, the following actions occur:

    • The EBCM disables the ABS/TCS/VSES for the duration of the ignition cycle.
    • The ABS indicator turns ON.
    • The TRACTION OFF indicator turns ON.
    • The DIC displays the SERVICE STABILITY SYSTEM message.
    • The DRP does not function optimally, or with ignition voltage less than 8.5 volts, the EBCM disables the DRP.
    • When the EBCM disables the DRP, the following actions also occur:
       - DTC C1248 sets.
       - The red BRAKE warning indicator turns ON.

Conditions for Clearing the DTC
    • The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
    • The electronic brake control module (EBCM) automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids
    • Test the charging system. Refer to Diagnostic System Check - Engine Electrical in Engine Electrical.
    • Possible causes of this DTC are the following conditions:
      • A charging system malfunction
      • An excessive battery draw
      • A weak battery
      • A faulty system ground

Test Description

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

  1. This step uses the scan tool to inspect the voltage to the EBCM.

    2.

  2. This step uses the scan tool to inspect the voltage to the dash integration module (DIM). A low voltage value in multiple modules indicates a concern in the charging system.

    3.

  3. This step verifies that the condition is still present.

Step

Action

Value(s)

Yes

No

1

Did you perform the ABS Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2

  1. Install a scan tool.
  2. Start the engine.
  3. With a scan tool, observe the Switched System Battery Voltage parameter in the DRP/ABS/TCS/TIM data list.

Does the scan tool indicate that the voltage is greater than the specified value?

10.5 V

Go to Diagnostic Aids

Go to Step 3

3

With a scan tool, observe the Battery Voltage parameter in the Dash Integration Module data list.

Does the scan tool indicate that the voltage is greater than the specified value?

10.5 V

Go to Step 4

Go to Diagnostic System Check - Engine Electrical in Engine Electrical

4
  1. Turn OFF the ignition.
  2. Disconnect the EBCM harness connector.
  3. Install the J 39700 universal pinout box using the J 39700-300 cable adaptor to the EBCM harness connector only.
  4. Test the ground circuits of the EBCM including the EBCM ground for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 7

Go to Step 5

5
  1. Reconnect the EBCM harness connector.
  2. Turn ON the ignition, with the engine OFF.
  3. Use the scan tool in order to clear the DTCs.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 6

Go to Diagnostic Aids

6

Important: Perform the setup procedure for the EBCM. An unprogrammed EBCM will result in the following conditions:

   • Inoperative of poorly functioning DRP/ABS/TCS/VSES/VES/TIM (if equipped)
   • Set DTC C1248 EBCM Turned the Red Brake Warning Indicator On
   • Set DTC C1255m3 EBCM Internal Malfunction

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

Did you complete the repair?

--

Go to Step 7

--

7
  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