Module Communications Network System: Other Mercury Mariner II

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

1. Stabilizing bus voltage
2. 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.

Communications Network - Hybrid

Vehicle communication utilizes both International Standards Organization (ISO) 9141 and controller area network (CAN) communications. ISO 9141 is used for diagnostic use only while CAN allows many modules to communicate with each other on a common network. CAN in-vehicle networking is a method for transferring data among distributed electronic modules via a serial data bus.

Without serial networking, intermodule communication requires dedicated, point to point wiring resulting in bulky, expensive, complex, and difficult to install wiring harnesses. Applying a serial data network reduces the number of wires, combining the signals on a single network. Information is sent to the individual control modules that control each function.

The vehicle has 3 module communication networks

1. ISO 9141
2. Medium speed (MS) CAN
3. High speed (HS) CAN

All 3 networks are connected to the data link connector (DLC). This makes diagnosis and testing of these systems easier by allowing one scan tool to be able to diagnose and control any module on the 3 networks from one connector. The DLC can be found under the instrument panel between the steering column and the audio unit.

Scheme 61

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

1. Stabilizing bus voltage
2. Eliminating electrical interference

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.

Special Tools Illustration Tool Name Tool Number 73III Automotive Meter 105-R0057 or equivalent Vehicle Communication Module (VCM) and Integrated Diagnostic System (IDS) software with appropriate hardware, or equivalent scan tool Flex Probe Kit 105-R025C or equivalent

Scheme 62

Scheme 63

ISO 9141 Communications Network

The ISO 9141 communications network is a single wire network. The ISO communications network does not permit intermodule communication and is only used for the parking aid module (PAM). When the scan tool communicates with the parking aid module, the scan tool must request all information, the module cannot initiate communications.

The ISO network operates at a maximum data transfer speed of 10 Kbps for bus messages and is designed for scan tool to module diagnostic use only.

The following fault chart describes the specific ISO 9141 network failures and their resulting symptom

ISO 9141 NETWORK COMMUNICATION FAULT CHART

MS-CAN

The MS-CAN uses an unshielded twisted pair cable of data (+) and data (-) circuits. The data (+) and the data (-) circuits are each regulated to approximately 2.5 volts during neutral or rested network traffic. As bus messages are sent on the data (+) circuit, voltage is increased by approximately 1.0 volt. Inversely, the data (-) circuit is reduced by approximately 1.0 volt when a bus message is sent. Multiple bus messages can be sent over the CAN circuits allowing multiple modules to communicate with each other. The MS-CAN is used for the instrument cluster (IC), the front controls interface module (FCIM), the front display interface module (FDIM), heating ventilation air conditioning (HVAC) module, the audio control module (ACM), the satellite digital audio receiver system (SDARS) module and the smart junction box (SJB) communications, and is designed for general information transfer. The MS-CAN will not communicate while certain faults are present, but will operate with diminished performance with other faults present. The MS-CAN bus may remain operational when 1 of the 2 termination resistors are not present.

The MS-CAN operates at a maximum data transfer speed of 125 Kbps for bus messages and is designed for general information transfer. The network will remain operational, but at a degraded level when certain circuit faults are present.

The following fault chart describes the specific MS-CAN failures and their resulting symptom

MS-CAN COMMUNICATION FAULT CHART

HS-CAN

The HS-CAN uses an unshielded twisted pair cable of data (+) and data (-) circuits. The data (+) and the data (-) circuits are each regulated to approximately 2.5 volts during neutral or rested network traffic. As bus messages are sent on the data (+) circuit, voltage is increased by approximately 1.0 volt. Inversely, the data (-) circuit is reduced by approximately 1.0 volt when a bus message is sent. Multiple bus messages can be sent over the CAN circuits allowing multiple modules to communicate with each other. The HS-CAN is a high speed communication network used for the instrument cluster (IC), the PCM, the ABS module, the occupant classification system module (OCSM), restraints control module (RCM), the traction battery control module (TBCM), the transmission control module (TCM), the power steering control module (PSCM) and the 4X4 control module communications, and designed for real time information transfer and control. The HS-CAN will not communicate while certain faults are present, but will operate with diminished performance with other faults present. The HS-CAN bus may remain operational when 1 of the 2 termination resistors are not present.

The HS-CAN operates at a maximum data transfer speed of 500 Kbps and is designed for real time information transfer and control. The network will remain operational, but at a degraded level when certain circuit faults are present.

The following fault chart describes the specific HS-CAN failures and their resulting symptom

HS-CAN COMMUNICATION FAULT CHART

The following chart describes the specific CAN messages broadcast by each module, and the module(s) that receive the message

CAN MODULE COMMUNICATION MESSAGE CHART - ESCAPE AND MARINER

CAN MODULE COMMUNICATION MESSAGE CHART - HYBRID