Can Bus

WARNING: This page is about a different car, the 2006 Dodge Sprinter. However, it is still accessible from the selected car via links, so may be relevant.

The CAN bus (controller area network) is a data bus system specifically design for inter module communication on this vehicle. The CAN bus consists of a special twisted two-core cable. Control modules are connected to this "twisted pair". The CAN bus incorporates two terminating resistors. One terminator is built into the Engine Control Module (ECM) and the other is built into the Sentry Key Remote Entry Module (SKREEM). Each resistor has a value of 120 ohms. The resistor condition can be confirmed by disconnecting the control module and measuring the resistance value at the appropriate control module pins. This measurement should read 120 ohms. The two CAN circuits, CAN C Bus (+) and CAN C Bus (-), are bridged by these two terminating resistors when all control modules are connected to the bus. These two resistors are connected to the CAN bus network in parallel. The measurement between the two twisted CAN circuits, with both the ECM and SKREEM connected, should measure a value of 60 ohms.

The CAN bus is bi-directional. This means that each connected control module can send and receive information. Transmission of data takes place redundantly via both circuits. The data bus levels are mirrored, meaning that if the binary level on one circuit is 0, the other circuit transmits binary level 1 and vice versa. The two line concept is used for two reasons: for fault identification and as a safety concept.

If a voltage peak occurs on just one circuit, the receivers can identify this as a fault and ignore the voltage peak. If a short circuit or interruption occurs on one of the two CAN circuits, a software hardware linked safety concept allows switching to a single-line operation. The defective CAN circuit is shut down. A specific data protocol controls how and when the participants can send and receive.

NOTE: It is important to note the CAN Bus circuits are used for inter-module communication only, and is no way connected to the K-Lines.

The following modules that use the CAN Bus on this vehicle are:

Automatic Temperature Control (ATC)
Controller Antilock Brake (CAB)
Engine Control Module (ECM)
Instrument Cluster (IC)
Sentry Key Remote Entry Module (SKREEM)
Shifter Assembly (SA)
Transmission Control Module (TCM)