Electronic Control Modules - Service Information: Overview Chrysler Crossfire I

DESCRIPTION

The Controller Area Network (CAN) data bus system is a multiplex system used for vehicle communications. Multiplexing is a system that enables the transmission of several messages over a single channel or circuit.

Many of the control modules in a vehicle require information from the same sensing device. Multiplexing reduces wire harness complexity, sensor current loads and controller hardware because each sensing device is connected to only one controller, which reads and distributes the sensor information to the other controllers over the data bus. Also, because each controller on the data bus can access the controller sensor inputs to every other controller on the data bus, more function and feature capabilities are possible.

A multiplex system allows the information flowing between controllers to be monitored using a diagnostic scan tool. This system allows a control module to broadcast message data out onto the bus where all other control modules can read the messages that are being sent. When a module reads a message on the data bus that it requires, it relays that message to its microprocessor. Each module ignores the messages on the data bus that it does not recognize.

OPERATION

Data exchange between modules is achieved by serial transmission of encoded data over a broadcast network. The Controller Area Network (CAN) data bus messages are carried over the bus in the form of variable pulse width modulated signals. The Engine CAN C Data Bus speed is 500 Kilo-bits per second (Kbps) (ignition on) while the Interior CAN B Data Bus speed is 83 Kilo-bits per second (Kbps).

The voltage network used to transmit messages requires biasing and termination. The biasing and termination for the network is supplied by the PCM and the SKREEM Module with a terminating resistor and a terminating capacitor. The Powertrain Control Module is the dominant node for the CAN C Engine Data Bus System and the Body Control Module is the dominant node for the CAN B Interior Data Bus System.

The CAN bus uses low and high voltage levels to generate signals. The voltage on the bus varies between zero and two and one-half volts. The low and high voltage levels are generated by means of variable-pulse width modulation to form signals of varying length.

When a module is transmitting on the bus, it is reading the bus at the same time to ensure message integrity.

Scheme 1

The Data Link Connector (DLC) (1) is located at the lower edge of the instrument panel (3) near the hood release (2). The exposed connector terminals are protected by a plastic cover which flips open if access is needed.

The 16-way Data Link Connector (DLC) provides a communication link between the DRB III(R) scan tool and the vehicle electronic control modules.

Scheme 2

The Powertrain Control Module (1) is concealed in the engine compartment inside the Control Module Box (2) located next to the Battery (3).

The Powertrain Control Module utilizes integrated circuitry and information carried on the Controller Area Network (CAN) data bus along with many hard wired inputs to monitor many sensor and switch inputs throughout the vehicle. In response to those inputs, the internal circuitry and programming of the Powertrain Control Module allow it to control and integrate many electronic functions and features of the vehicle through both hard wired outputs and the transmission of electronic message outputs to other electronic modules in the vehicle over the CAN data bus.

The Powertrain Control Module for this model is serviced only as a complete unit. A Powertrain Control Module can only be repaired by, or replaced through an authorized electronic warranty repair station. Refer to the latest version of the warranty policies and article for a current listing of authorized electronic repair stations.

Scheme 3

The Powertrain Control Module (1) is concealed in the engine compartment inside the Control Module Box (3) located next to the Battery (2).

The Powertrain Control Module utilizes integrated circuitry and information carried on the Controller Area Network (CAN) data bus along with many hard wired inputs to monitor many sensor and switch inputs throughout the vehicle. In response to those inputs, the internal circuitry and programming of the Powertrain Control Module allow it to control and integrate many electronic functions and features of the vehicle through both hard wired outputs and the transmission of electronic message outputs to other electronic modules in the vehicle over the CAN data bus.

The Powertrain Control Module for this model is serviced only as a complete unit. A Powertrain Control Module can only be repaired by, or replaced through an authorized electronic warranty repair station. Refer to the latest version of the warranty policies and article for a current listing of authorized electronic repair stations.

The Powertrain Control Module is a pre-programmed, microprocessor-based digital computer. It regulates ignition timing, air-fuel ratio, emission control devices, charging system, certain transmission features, speed control, air conditioning compressor clutch engagement and idle speed. The Powertrain Control Module can adapt its programming to meet changing operating conditions.

The Powertrain Control Module receives input signals from various switches and sensors. Based on these inputs, the Powertrain Control Module regulates various engine and vehicle operations through different system components. These components are referred to as Powertrain Control Module outputs. The sensors and switches that provide inputs to the Powertrain Control Module are considered Powertrain Control Module inputs.

The Powertrain Control Module adjusts ignition timing based upon inputs it receives from sensors that react to: engine rpm, manifold absolute pressure, engine coolant temperature, throttle position, transmission gear selection (automatic transmission), vehicle speed and the brake switch.

The Powertrain Control Module adjusts idle speed based on inputs it receives from sensors that react to: throttle position, vehicle speed, transmission gear selection, engine coolant temperature and from inputs it receives from the air conditioning clutch switch and brake switch.

Based on inputs that it receives, the Powertrain Control Module adjusts ignition timing. The Powertrain Control Module also adjusts the generator charge rate through control of the generator field and provides speed control operation.

The Transmission Control Module controls all electronic operations of the transmission. The Transmission Control Module receives information regarding vehicle operation from both direct and indirect inputs and selects the operational mode of the transmission. Direct inputs are hardwired to and used specifically by the Transmission Control Module. Indirect inputs originate from other components/modules and are shared with the Transmission Control Module via the vehicle Controller Area Network (CAN) bus.

Some examples of direct inputs to the Transmission Control Module are

1. Traction System Relay Output voltage
2. Trans Temp Sensor - P/N Switch
3. N2 and N3 Speed Sensors

Some examples of indirect inputs to the Transmission Control Module are

1. Controller Area Network (CAN) Bus Modules
2. Shift Lever Assembly
3. Brake Lamp Switch

Based on the information received from these various inputs, the Transmission Control Module determines the appropriate shift schedule and shift points, depending on the present operating conditions and driver demand. This is possible through the control of various direct and indirect outputs.

Some examples of Transmission Control Module direct outputs are

1. 1-2/4-5 Solenoid
2. 2-3 Solenoid
3. 3-4 Solenoid
4. TCC Solenoid
5. Modulation Pressure Solenoid
6. Shift Pressure Solenoid
7. DRB III(R) Scan Tool Communication
8. Sensor Supply Voltage
9. Solenoid Supply Voltage

Some examples of Transmission Control Module indirect outputs are

1. Transmission Temperature (to Powertrain Control Module)
2. Shift Lever Position (to Powertrain Control Module)

In addition to monitoring inputs and controlling outputs, the Transmission Control Module has other important responsibilities and functions

1. Storing and selecting appropriate Shift Schedules
2. System self-diagnostics
3. Diagnostic capabilities (with DRB III(R) scan tool)

Note. If the TCM has been replaced, the "TCM Quick Learn" procedure must be performed. (Refer to ELECTRICAL/ELECTRONIC CONTROL MODULES/TRANSMISSION CONTROL MODULE - STANDARD PROCEDURE) .

The primary functions of the Controller Antilock Brake (CAB) are to

1. Monitor the Antilock Brake System (ABS) for proper operation.
2. Detect wheel locking or wheel slipping tendencies by monitoring the speed of all four wheels of the vehicle.
3. Control fluid modulation to the wheel brakes while the system is in an ABS mode.
4. Store diagnostic information.
5. Provide communication to the DRB III(R) scan tool while in diagnostic mode.
6. Illuminate the amber ABS warning indicator lamp.
7. Illuminate the brake assist (BAS)/electronic stability program (ESP) lamp on the instrument panel when a traction control event occurs.

The CAB constantly monitors the Antilock Brake System for proper operation. If the CAB detects a fault, it will turn on the amber ABS warning indicator lamp and disable the Antilock Braking System. The normal base braking system will remain operational.

The CAB continuously monitors the speed of each wheel through the signals generated by the wheel speed sensors to determine if any wheel is beginning to lock. When a wheel locking tendency is detected, the CAB commands the CAB command coils to actuate. The coils then open and close the valves in the Hydraulic Control Unit (HCU) that modulate brake fluid pressure in some or all of the hydraulic circuits. The CAB continues to control pressure in individual hydraulic circuits until a locking tendency is no longer present.

The CAB contains a self-diagnostic program that monitors the Antilock Brake System for system faults. When a fault is detected, the amber ABS warning indicator lamp is turned on and the Diagnostic Trouble Code (DTC) is then stored in a diagnostic program memory. These DTCs will remain in the CAB memory even after the ignition has been turned off. The DTCs can be read and cleared from the CAB memory by a technician using the DRB III(R) scan tool.

The Sentry Key Remote Entry Module (SKREEM) has the following functions: receiving and evaluating the Radio Frequency (RF) keyless entry remote signal, actuation of door locks in conjunction with the Central Locking Pump/Security System Module, and enabling the vehicle theft security alarm with confirmation via the turn signals. When the RKE transmitter is operated, an RF signal is transmitted. If the SKREEM recognizes the RF signal as valid, it actuates the Central Locking Pump/Security System Module through the Body Control Module. The vehicle is then locked or unlocked through the power locks system. Connected to the SKREEM is a Sentry Key Antenna Ring which surrounds the ignition lock cylinder. When the ignition is switched on, the Sentry Key Antenna Ring is supplied with power. A data block is transmitted inductively via the Sentry Key Antenna Ring to the SKREEM and then on to the Powertrain Control Module. If the antenna ring data block content is invalid or if vehicle battery power is too low to build up enough power for the antenna ring, the Powertrain Control Module will not receive the proper signal. This is displayed with the message "Start Error" in the Instrument Cluster.

The SKREEM contains an RF transceiver and a microprocessor. The SKREEM transmits RF signals to and receives RF signals from the ignition key transponder through a tuned Sentry Key Antenna Ring that is wired to the SKREEM. If the Sentry Key Antenna Ring is not mounted properly around the ignition lock cylinder housing, communication problems between the SKREEM and the ignition key may arise. These communication problems will result in ignition key transponder-related faults. The SKREEM also communicates over the Controller Area Network (CAN) data bus with the Powertrain Control Module (PCM), the Instrument Cluster, the Body Control Module (BCM), and/or the DRB III(R) scan tool.

The SKREEM retains in memory the ID numbers of any ignition key transponder that is programmed into it. For added system security each SKREEM is programmed with a unique secret key code. This code is stored in memory, sent over the CAN data bus to the PCM, and is encoded to the transponder of every ignition key that is programmed into the SKREEM.

In the event that a SKREEM replacement is required, the secret key code can be transferred to the new SKREEM from the PCM using the DRB III(R) scan tool and the ignition key system replacement programming procedure. Proper completion of the ignition key system initialization will allow the existing ignition keys to be programmed into the new SKREEM so that new keys will not be required. In the event that the original secret key code cannot be recovered, SKREEM replacement will also require new ignition keys. The DRB III(R) scan tool will alert the technician during the key reprogramming procedure if new ignition keys are required.

The sentry key system performs a self-test each time the ignition switch is turned to the ON/RUN position and will store fault information in the form of Diagnostic Trouble Codes (DTCs) in SKREEM memory if a system malfunction is detected. The SKREEM can be diagnosed and any stored DTCs can be retrieved using a DRB III(R) scan tool. Refer to ELECTRONIC CONTROL MODULES - ELECTRICAL DIAGNOSTICS .

Scheme 4

1. Disconnect the negative battery cable.
2. Remove the Instrument Cluster. «(Refer to ELECTRICAL/INSTRUMENT CLUSTER - REMOVAL)»(ref-250619-S04395837002007031500000) .
3. Disconnect the 2-pin CAN BUS harness connector (1) from the SKREEM module.
4. Disconnect the 2-pin harness connector for the sentry key antenna ring.
5. Disconnect the 18-pin harness connector (1) from the SKREEM module.
6. Press the retaining tabs apart.
7. Remove the SKREEM module from the base plate.

The Body Control Module is designed to control and integrate many of the electronic features and functions of the vehicle. The microprocessor-based Body Control Module hardware and software monitors many hardwired switch and sensor inputs as well as those resources it shares with other electronic modules in the vehicle through its communication over the Controller Area Network (CAN) Bus. The internal programming of the Body Control Module microprocessor allows the Body Control Module to determine the tasks it needs to perform and their priorities. The Body Control Module programming then performs those tasks and provides features through both CAN Bus communication with other electronic modules and hardwired outputs to a number of relays. These relays provide the Body Control Module with the ability to control numerous high current accessory systems in the vehicle.

The Body Control Module circuitry operates on battery current received through fuses in the Underhood Accessory Fuse Block on a non-switched fused B(+) circuit, a fused ignition switch output (start-on/run) circuit, and a fused ignition switch output (start-on/run-accessory) circuit. This arrangement allows the Body Control Module to provide some features regardless of the ignition switch position. The Body Control Module circuitry is grounded through the chassis behind the right side lower A-pillar kick panel.

The Body Control Module monitors its own internal circuitry as well as many of its input and output circuits and will store a Diagnostic Trouble Code (DTC) in electronic memory for any failure it detects. These DTCs can be retrieved and diagnosed using a DRB III(R) scan tool. Refer to ELECTRONIC CONTROL MODULES - ELECTRICAL DIAGNOSTICS .

Scheme 5

1. Disconnect the negative battery cable (2).
2. Slide the clips forward to remove the plastic control module box cover (1).
3. Holding the metal body control module retaining clip (1) back, pull the body control module up and out of the control module box.
4. Disconnect the electrical connectors (1) by first sliding the grey windshield wiper connector lock to the right and removing the windshield wiper electrical connector. Then, pull the metal body control module connector lock up to unlock and disconnect the rest of the body control module electrical connectors.
5. Remove the body control module from the control module box (2).

The PTCM controls each set of hydraulic cylinders through the power top hydraulic assembly. The power top hydraulic assembly operates the hydraulic cylinders and is monitored by the PTCM to control each step of the raising and lowering of the convertible top. The PTCM also controls both power windows through the Controller Area Network (CAN) lines to lower and raise the power windows when the power top switch is depressed.

See also:
• ELECTRONIC CONTROL MODULES - ELECTRICAL DIAGNOSTICS