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:
- 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.
- 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.
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
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.