CAN Troubleshooting

ECU does not respond to CCP reprogramming requests

1. Verify that the ECU has power.

2. Verify the CCP settings are correct.

3. Verify the CAN bus has proper termination resistance.

4. Verify the ECU is in programming mode with the Flash Code Output.

5. If there is no Flash Code Output, see My ECU is dead - What should I do?

See also CCP Troubleshooting guide in the OpenECU Simulink User Guide.

Reprogramming / CCP works but 'normal' CAN doesn't

1. Verify that power to the ECU is completely removed after reprogramming is complete. If power is not cycled after the ECU has been reprogrammed, then it will remain in programming mode.

2. Verify the CAN bus has proper termination resistance.

3. Use the CAN bus status block to see if there are any bus errors.

4. Verify the CAN configuration settings. Some OpenECU's support more than one CAN bus, so a separate CAN Configuration block is needed for each bus.

   • If the ECU is unable to transmit, verify the CAN output block settings.

   • If the ECU is unable to receive, verify the CAN input block settings.

5. If the same bus is used for both CAN and CCP, verify that the bus speed is the same on the CCP tool and all nodes on the bus.

CAN stops working when I connect other ECU's to the bus

1. Verify the CAN bus has proper termination resistance

2. Verify the baud rates on all devices. The OpenECU baud rate is configured in the CAN configuration settings.

3. Verify that there are no clashing CAN message IDs.

CAN or CCP keep dropping out or work intemittently

1. Verify the CAN bus has proper termination resistance

2. Verify that the CPU is not overloaded. OpenECU treats CCP as low priority, so if the CPU load is too high, then CCP messages may be ignored. The CPU load can be monitored with the CPU Loading block. See also Application Resource Usage

3. Verify that the ECU is not resetting.
4. Dropped connection on CCP may cause calibration tool to ask to reflash the calibration data,

CAN Termination Resistance

A CAN bus has a 120 ohm termination resistor across the High and Low signals at each end of the bus. These termination resistors may be inside an ECU on the CAN bus, or in the wire harness. An OpenECU module may come with the termination resistor unpopulated, or populated on one or both CAN buses. See the Technical Specification for your ECU to see if the termination resistors are populated. This will be indicated in the "Loading" column of the connector pin out table.

More Information

• https://en.wikipedia.org/wiki/CAN_bus

• http://www.kvaser.com/about-can/the-can-protocol

Still having trouble?

For additional help Contact OpenECU Support.