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Mark Bisig
Mark Bisig, Auto Service Technician
Category: Chevy
Satisfied Customers: 158
Experience:  28 years at a Chevrolet Dealer, ASE Master Technician, GM Master Technician
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diagnostic repair for chassis codes C1254 and C1298 on ...

Resolved Question:

diagnostic repair for chassis codes C1254 and C1298 on a 2002 Pontiac Grand Am
Submitted: 6 years ago.
Category: Chevy
Expert:  Mark Bisig replied 6 years ago.
HelloCustomer Just what are you looking for dia charts ?
Customer: replied 6 years ago.
Reply to Mark Bisig's Post: Diagnostic charts would be great.
Expert:  Mark Bisig replied 6 years ago.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern: This is a bulletin for code C1298

 

A tech may have difficulty finding information on DTC C1298. The information is not in available service information.

Recommendation/Instructions:

 

The DTC C1298 indicates either the EBCM is not transmitting information to the PCM or the PCM is not receiving information from the EBCM. The TAC cases indicate that the EBCM grounds or applied ignition voltage is the most common cause of the code setting, outside of an EBCM failure. The particular grounds in question are G102, G103, and G105. The applied ignition voltage is fed by the ignition switch, circuit 3, through the ABS/EVO/IGN 15 amp fuse in the underhood fuse block to pin A11 of the EBCM on circuit 139.

Checking and qualifying these circuits should lead the technician to the cause of the DTC setting.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

 

 

DTC C1254

Circuit Description

The microprocessor contains a data storage area, keep alive memory, which can save pertinent data when the ignition is turned OFF. The keep alive memory (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.

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 when ever new data is written to them. This is called the running checksum.

To check the keep alive memory (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 EBCM disables the DRP/ABS/TCS 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 Off indicator turns ON.
  • The EBCM will not send serial data messages.
  • The EBCM will not send the requested torque output to the PCM.

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 inXXXXXcycles.

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 keep alive memory check sum 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.

2. Tests for an open in the ground circuits of the body control module.

4. Verifies the proper operation of the charging system.

6. Determines whether the DTC resets.

Step

Action

Yes

No

Schematic Reference: ABS Schematics

Connector End View Reference: ABS Connector End Views

1

Did you perform the ABS Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - ABS

2

  1. Turn OFF the ignition.

Important

Removing battery voltage or ground from the EBCM will result in the following conditions:

    • Loss of the TIM learned tire inflation configuration parameters in the EBCM
    • The EBCM sets DTC C1245

When the diagnosis is complete, inspect the tire pressures and perform the TIM reset. Refer to Tire Pressure Monitor Reset Procedure in Tire Pressure Monitoring.

  1. Disconnect the EBCM harness connector.
  2. Install the J 39700 universal breakout box using the J 39700-99 breakout box adapter to the EBCM harness connector only.
  3. Test the module ground circuit of the EBCM 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 - Engine Electrical in Engine Electrical.

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 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 and Poor Connections in Wiring Systems

7

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

Did you complete the repair?

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?

 

 

 

Mark Bisig, Auto Service Technician
Category: Chevy
Satisfied Customers: 158
Experience: 28 years at a Chevrolet Dealer, ASE Master Technician, GM Master Technician
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