Module Communications Network System: Other Ford Mustang V

Audio Unit

The audio unit uses the medium speed CAN for communication with the diagnostic tool and all the modules on the medium speed CAN.

For additional information, refer to ENTERTAINMENT SYSTEM - GENERAL INFORMATION .

Instrument Cluster

The instrument cluster uses the high speed CAN and the medium speed CAN for communication with the diagnostic tool and all the modules on the high speed CAN and medium speed CAN. The instrument cluster serves as a communications network gateway between the high speed CAN and the medium speed CAN. The instrument cluster displays a variety of information.

For additional information, refer to INSTRUMENT CLUSTER .

Powertrain Control Module (PCM)

The PCM uses the high speed CAN for communication with the diagnostic tool and all the modules on the high speed CAN. The PCM controls the engine for better fuel economy, emissions control, failure mode detection and data storage.

Refer to the INTRODUCTION - GASOLINE article for diagnosis and testing of the PCM.

Restraint Control Module (RCM)

The RCM uses the International Standards Organization (ISO) 9141 communication network for communication with the diagnostic tool. The RCM controls the deployment of the air bags based on sensor input.

For additional information, refer to SUPPLEMENTAL RESTRAINT SYSTEM .

Smart Junction Box (SJB)

The SJB uses the medium speed CAN for communication with the diagnostic tool and all the modules on the medium speed CAN. The SJB is a combination of a multifunction module and an interior power junction box.

For additional information, refer to MULTIFUNCTION ELECTRONIC MODULES .

Refer to COMPUTER DATA LINES for schematic and connector information.

SPECIAL TOOL CHART 73III Automotive Meter 105-R0057 or equivalent Worldwide Diagnostic System (WDS) Vehicle Communication Module (VCM) with appropriate adapters, or equivalent diagnostic tool Flex Probe Kit 105-R025B or equivalent

High Speed Controller Area Network (CAN)

The high speed CAN is an unshielded twisted pair cable, data plus circuit 1827 (WH/LG) and data minus circuit 1828 (PK/LG).

The high speed CAN is a high speed communication network used for the anti-lock brake system (ABS) module, the instrument cluster and the powertrain control module (PCM) communication. The ABS module, the PCM and the instrument cluster use the high speed CAN to communicate information back and forth such as engine RPM, vehicle speed and odometer. The modules on the high speed CAN are ignition switched. The high speed CAN is only on when the key is in the ON position.

The high speed CAN is not designed to operate under single point fault conditions. If either circuit is shorted to voltage or the high speed CAN data plus is shorted to ground, module-to-module and module-to-tester communication is not possible. If the high speed CAN data minus is shorted to ground or an open exists on either bus line, module-to-module and module-to-tester communication is marginal at best. The high speed CAN bus may remain operational when 1 of the 2 termination resistors are not present. If there are issues with the high speed CAN, there may be missing functionality and problems connecting with a diagnostic tool. On the CAN, there are 2 terminating modules which are composed of the PCM and the instrument cluster which are located at the far opposite ends of the CAN wiring.

Medium Speed Controller Area Network (CAN)

The medium speed CAN is an unshielded twisted pair cable, data plus circuit 1847 (WH/OG) and data minus circuit 1848 (PK/OG).

The medium speed CAN is a medium speed communication network used for the audio unit, the instrument cluster, and the smart junction box (SJB) communication. The SJB, the instrument cluster and the audio unit use the medium speed CAN to communicate information back and forth such as dimming, fuel level, turn signal indicator on the instrument cluster and vehicle compensated volume. The medium speed can be awake when the key is in the OFF position to carry out functions such as delay accessory. In order to carry out diagnostics, it is necessary to have the key in the ON position.

The medium speed CAN is not designed to operate under single point fault conditions. If either circuit is shorted to voltage or the medium speed CAN data plus is shorted to ground, module-to-module and module-to-tester communication is not possible. If the medium speed CAN data minus is shorted to ground or an open exists on either bus line, module-to-module and module-to-tester communication is marginal at best. The medium speed CAN bus may remain operational when 1 of the 2 termination resistors are not present. If there are issues with the medium speed CAN, there may be missing functionality and problems connecting with a diagnostic tool. On the CAN, there are 2 terminating modules which are composed of the SJB and the instrument cluster which are located at the far opposite ends of the CAN wiring.

International Standards Organization (ISO) 9141 Communication Network

The ISO 9141 communication network is a single circuit communication network, circuit 70 (LB/WH). The ISO 9141 communication network does not permit intermodule communication. When the diagnostic tool communicates to modules on the ISO 9141 communication network, the diagnostic tool must ask for all information; the modules cannot initiate communication. The ISO 9141 communication network does not function if the circuit is shorted to ground, shorted to voltage or is open. Also, if one of the modules on the ISO 9141 communication network loses power or shorts internally, communication to that module fails. The ISO 9141 communication network is used to communicate with the restraint control module (RCM).

Possible Causes

1. high speed CAN circuit 1827 (WH/LG) open
2. high speed CAN circuit 1828 (PK/LG) open
3. ABS module C135
4. ABS module

1. medium speed CAN circuit 1847 (WH/OG) open
2. medium speed CAN circuit 1848 (PK/OG) open
3. audio unit C290a
4. audio unit

1. high speed CAN circuit 1827 (WH/LG) open
2. high speed CAN circuit 1828 (PK/LG) open
3. instrument cluster C220
4. instrument cluster

1. medium speed CAN circuit 1847 (WH/OG) open
2. medium speed CAN circuit 1848 (PK/OG) open
3. instrument cluster C220
4. instrument cluster

1. high speed CAN circuit 1827 (WH/LG) open
2. high speed CAN circuit 1828 (PK/LG) open
3. PCM C175b
4. PCM

1. medium speed CAN circuit 1847 (WH/OG) open
2. medium speed CAN circuit 1848 (PK/OG) open
3. SJB C2280b
4. SJB

1. high speed CAN circuit 1827 (WH/LG) short to voltage, short to ground or open
2. high speed CAN circuit 1828 (PK/LG) short to voltage, short to ground or open
3. DLC C251
4. ABS module C135
5. instrument cluster C220
6. PCM C175b
7. ABS module
8. instrument cluster
9. PCM

1. medium speed CAN circuit 1847 (WH/OG) short to ground, short to voltage, or open
2. medium speed CAN circuit 1848 (PK/OG) short to ground, short to voltage, or open
3. DLC C251
4. audio unit C290a
5. instrument cluster C220
6. SJB C2280b
7. audio unit
8. instrument cluster
9. SJB

1. ISO 9141 communications network circuit 70 (LB/WH) short to ground, short to voltage or open
2. DLC C251
3. RCM C2041a
4. RCM

1. fuse
2. DLC C251
3. diagnostic tool
4. circuit 570 (BK/WH) open
5. circuit 1047 (LG/RD) open
6. circuit 1205 (BK) open