CAN Communication

DTC Index

NOTE: Generic scan tools may not read the codes listed, or may read only 5-digit codes. Match the 5 digits from the scan tool to the first 5 digits of the 7-digit code listed to identify the fault (the last 2 digits give extra information read by the manufacturer-approved diagnostic system).

"Lost communication" codes
Lost communication codes mean that a module is not receiving CAN information from another module, but that its own transmissions are OK.

These codes typically indicate a break in the circuit.

Where a "lost communication" code is set, check the customer complaint to see if there are reports of warning lights, etc for other vehicle systems (which may seem unconnected with the module setting the code), and carry out a complete vehicle code read.

Review the codes stored in the vehicle to identify any trends, such as a number of modules reporting having lost communication with a particular module.

NOTE: Do not interpret "timeout" codes as a module or circuit fault. These codes are sometimes set when the networks are busy and a module cannot get its signal onto the network in the time allowed.

Check the suspect module power and ground supplies, and the CAN circuits between modules and repair as necessary.

Investigate, repair and clear all stored codes and retest for normal operation.

"Bus off" codes
The references to "bus" and its condition refer to the network concerned and the modules on that network.

If a code says that a module is bus off, this means that the module has detected errors, and has disabled CAN transmission and disconnected itself from the network to allow the rest of the network to function. At this point, the bus off code is set.

As the most common cause of bus off codes is a short circuit in the CAN network, check the CAN circuits using the electrical guides before condemning a module.