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For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 DeVille 🢒 Accessories 🢒 Navigation Systems 🢒 DTC C1254

Circuit Description

The microprocessor contains a data storage area, keep alive memory (KAM), which can save pertinent data when the ignition is turned OFF. The KAM data is lost if battery power or module ground is removed from the module. The KAM area is an integral part of the microprocessor and cannot be serviced separately.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C1254 Abnormal Shutdown Detected

Conditions for Running the DTC

The ABS conditions and the braking conditions are normal.

Conditions for Setting the DTC

The microprocessor calculates a checksum on those areas of memory that hold critical operation data. This is done at a regular interval and is called the periodic checksum. The microprocessor also calculates a checksum on these memory locations whenever new data is written to them. This is called the running checksum.

To check the KAM, the microprocessor compares the periodic checksum to the running checksum. If they do not match, the microprocessor sets the DTC.

Action Taken When the DTC Sets

If equipped, the following actions occur:

    • The electronic brake control module (EBCM) disables the dynamic rear proportion (DRP)/ABS/traction control system (TCS)/vehicle stability enhancement system (VSES) for the duration of the ignition cycle.
    • The EBCM disables the variable effort steering (VES) for the duration of the ignition cycle.
    • The ABS indicator turns ON.
    • The Traction Control indicator turns ON.
    • The driver information center (DIC) displays the Service Stability System and Service Steering System messages.
    • The red Brake Warning indicator turns ON.
    • The EBCM will also set DTC C1248.
    • The EBCM will not send serial data messages.
    • The EBCM will not send the requested torque output to the powertrain control module (PCM).
    • The EBCM will not send the steering angle pulse width modulator (PWM) output to the electronic suspension control (ESC) module.

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

Diagnostic Aids

Possible causes of this DTC are the following conditions:

    • A loss of battery ground
    • A disconnected battery
    • A running reset
         A running reset is detected when the KAM checksum is not updated properly.
    • A sudden drop in the system voltage to less than 5 volts
    • Long extended engine cranks that cause the battery voltage to drop
    • Poor power or ground connections
    • An internal EBCM malfunction

Test Description

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

  1. This step tests for an open in the ground circuits of the EBCM.

    2.

  2. This step verifies the proper operation of the charging system.

    3.

  3. This step determines whether the DTC resets.

Step

Action

Yes

No

Schematic Reference: Antilock Brake System Schematics

Connector End View Reference: Antilock Brake System Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Turn OFF the ignition.
  2. Disconnect the electronic brake control module (EBCM) harness connector.
  3. Install the J 39700 Universal Pinout Box using the J 39700-300 Cable Adapter to the EBCM harness connector only.
  4. Test both 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 8

Go to Step 3

3

Has the battery been disconnected recently?

Go to Step 8

Go to Step 4

4

Test the charging system. Refer to Diagnostic System Check - Vehicle in Vehicle DTC Information.

Did you find and correct the condition?

Go to Step 8

Go to Step 5

5

Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 8

Go to Step 6

6

  1. Use the scan tool in order to clear the DTCs.
  2. With the scan tool, perform the Automated Test.

Does the DTC reset?

Go to Step 7

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

7

Replace the EBCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 8

--

8
  1. Use the scan tool in order to clear the DTCs.
  2. With the scan tool, perform the Automated Test.

Does the DTC reset?

Go to Step 2

System OK