Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
A tech may have difficulty finding information on DTC C1298. The information is not in available service information.
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.
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.
The ABS conditions and the braking conditions are normal.
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.
If equipped, the following actions occur:
Possible causes of this DTC are the following conditions:
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.
Schematic Reference: ABS Schematics
Connector End View Reference: ABS Connector End Views
Did you perform the ABS Diagnostic System Check?
Go to Step 2
Go to Diagnostic System Check - ABS
Removing battery voltage or ground from the EBCM will result in the following conditions:
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.
Did you find and correct the condition?
Go to Step 8
Go to Step 3
Has the battery been disconnected recently?
Go to Step 4
Test the charging system. Refer to Diagnostic System Check - Engine Electrical in Engine Electrical.
Go to Step 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.
Go to Step 6
Does the DTC reset?
Go to Step 7
Go to Testing for Intermittent and Poor Connections in Wiring Systems
Replace the EBCM. Refer to Electronic Brake Control Module (EBCM) Replacement .
Did you complete the repair?