E 250 V8-5.4L (2008)
The MS-CAN is a medium speed communication network used for the following modules:
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Instrument cluster (IC)
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Vehicle security module (VSM) (if equipped)
HS-CAN Operation
The HS-CAN uses an unshielded twisted pair cable, data bus (+) and data bus (-) circuits. In addition to scan tool communication, this network allows
sharing of information between all modules on the network.
The HS-CAN is a high speed communication network used for the following modules:
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ABS module
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IC
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PCM
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Restraints control module (RCM)
Network Termination
The CAN uses a network termination circuit to improve communication reliability. The network termination of the CAN bus takes place inside the
termination modules by termination resistors. Termination modules are located at either end of the bus network. As network messages are broadcast in
the form of voltage signals, the network voltage signals are stabilized by the termination resistors. Each termination module has a 120 ohm resistor
across the positive and negative bus connection in the termination module. With 2 termination modules on each network, and the 120 ohm resistors
located in a parallel circuit configuration, the total network impedance, or total resistance, is 60 ohms.
Network termination improves bus message reliability by:
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Stabilizing bus voltage
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Eliminating electrical interference
Gateway Module
The instrument cluster (IC) is the gateway module, translating HS-CAN to MS-CAN and vice versa. This information allows a message to be
distributed throughout both networks. The IC is the only module on this vehicle that has this ability.