PT Cruiser L4-2.4L Turbo VIN G (2004)
Information Bus: Description and Operation
The Programmable Communication Interface Multiplex system (PCI Bus) consist of a single wire. The Body Control Module (BCM) acts as a splice to
connect each module and the Data Link Connector (DLC) together. Each module is wired in parallel to the data bus through its PCI chip set and uses its
ground as the bus reference. The wiring is a minimum 20 gage wire.
Various modules exchange information through a communications port called the PCI Bus. The Power-train Control Module (PCM) transmits the
Malfunction Indicator Lamp (Check Engine) On/Off signal and engine RPM on the PCI Bus. The PCM receives the Air Conditioning select input,
transaxle gear position inputs over the PCI Bus. The PCM also receives the air conditioning evaporator temperature signal from the PCI Bus.
The following components access or send information on the PCI Bus.
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Instrument Panel
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Body Control Module
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Air Bag System Diagnostic Module
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Full ATC Display Head (if equipped)
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ABS Module
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Transmission Control Module
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Powertrain Control Module
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Travel Module
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SKIM
COMMUNICATION
The Programmable Communication Interface or PCI Bus is a single wire multiplexed network capable of supporting binary encoded messages shared
between multiple modules. The PCI bus circuit is identified as D25 and is violet with a yellow tracer. The modules are wired in parallel. Connections are
made in the harness using splices. The following modules are used on 2003 PT:
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Airbag Control Module
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Controller Antilock Brake
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Powertrain Control Module (Gas only)
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Engine Control Module (Diesel only)
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Remote Keyless Entry Module
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Sentry Key Immobilizer Module
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Radio
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Mechanical Instrument Cluster
Each module provides its own bias and termination in order to transmit and receive messages. The bus voltage is at zero volts when no modules are
transmitting and is pulled up to about seven and a half volts when modules are transmitting.
