Module Communications Network - Except Electric: Other Ford Focus III

Network Termination

The CAN uses network termination to improve communication reliability. Termination modules are located at both ends of the 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 an internal 120 ohm resistor that bridges across the positive and negative bus connection. With two 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 IPC and BCM are gateway modules. The IPC translates messages on the Medium Speed Controller Area Network (MS-CAN) to the Infotainment Controller Area Network (I-CAN) and vice versa. The BCM translates messages on the High Speed Controller Area Network (HS-CAN) to the Medium Speed Controller Area Network (MS-CAN) and vice versa. This allows a message to be distributed throughout all 3 networks.

The IPC and the BCM are the only modules on this vehicle that have this ability.

High Speed Controller Area Network (HS-CAN)

The High Speed Controller Area Network (HS-CAN) operates at a maximum data transfer speed of 500 Kbps and is designed for real time powertrain information transfer and control.

Modules on the High Speed Controller Area Network (HS-CAN) communicate using bussed messages. The High Speed Controller Area Network (HS-CAN) uses an unshielded twisted pair cable, data bus (+) and data bus (-) circuits. In addition to scan tool communication, the High Speed Controller Area Network (HS-CAN) allows sharing of information between all modules on the network.

Medium Speed Controller Area Network (MS-CAN)

The Medium Speed Controller Area Network (MS-CAN) operates at a maximum data transfer speed of 125 Kbps and is designed for general information transfer.

Modules on the Medium Speed Controller Area Network (MS-CAN) communicate using bussed messages. The Medium Speed Controller Area Network (MS-CAN) uses an unshielded twisted pair cable, data bus (+) and data bus (-) circuits. In addition to scan tool communication, the Medium Speed Controller Area Network (MS-CAN) allows sharing of information between all modules on the network.

Infotainment Controller Area Network (I-CAN)

The Infotainment Controller Area Network (I-CAN) operates at a maximum data transfer speed of 500 Kbps and is designed for real time audio and multimedia information transfer and control.

Modules on the Infotainment Controller Area Network (I-CAN) communicate using bussed messages. Infotainment Controller Area Network (I-CAN) uses an unshielded twisted pair cable, data bus (+) and data bus (-) circuits. The Infotainment Controller Area Network (I-CAN) allows sharing of information between all modules on the network.

The Infotainment Controller Area Network (I-CAN) is connected to the DLC, but the Infotainment Controller Area Network (I-CAN) modules communicate with the scan tool over the Medium Speed Controller Area Network (MS-CAN). The IPC is used as a gateway for the messages to transfer between the scan tool and the modules on the Infotainment Controller Area Network (I-CAN).

Controller Area Network (CAN) Fault Tolerance

Note. The oscilloscope traces shown in illustration are from the IDS oscilloscope taken using the IDS pre-configured CAN settings. The traces are for both data (+) and data (-) taken simultaneously (2-channel) at a sample rate of 1 mega-sample per second (1MS/s) or greater.

Scheme 8

The data (+) and data (-) circuits are each regulated to approximately 2.5 volts during neutral or rested network traffic. As 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 message is sent.

Successful communication of a message can usually be identified by the slight spike at the end of a message transmission. Any signals that are significantly different than the normal CAN waveform may cause network Diagnostic Trouble Codes (DTCs) (U-codes) to set or may cause a complete network outage.

Scheme 9

In the event the data (+) and data (-) circuits become shorted together, the signal stays at base voltage (2.5V) continuously and all communication capabilities are lost.

Scheme 10

In the event the data (+) circuit becomes shorted to ground, both the data (+) and data (-) circuits are pulled low (0V) and all communication capabilities are lost.

Scheme 11

In the event the data (-) circuit becomes shorted to ground, the data (-) circuit is pulled low (0V) and the data (+) circuit reaches near-normal peak voltage (3.0V) during communication but falls to 0V instead of normal base voltage (2.5V). Communication may continue but at a degraded level.

Scheme 12

In the event the data (+) circuit becomes shorted to battery voltage, the data (+) circuit is pulled high (12V) and the data (-) circuit falls to abnormally high voltage (above 5V) during communication and reaches battery voltage (12V) for peak voltage. Communication may continue but at a degraded level.

Scheme 13

In the event the data (-) circuit becomes shorted to battery voltage, both the data (+) and data (-) circuits are pulled high (12V) and all communication capabilities are lost.

Scheme 14

Rhythmic oscillations, inductive spikes or random interference can corrupt the network communications. The corruption signal source may be outside electrical interference such as motors or solenoids or internal interference generated from a module on the network. In some cases, an open in either the data (+) or data (-) circuit to a network module may cause the module to emit interference on the one circuit which is still connected. The trace shown in illustration is an example of a "sawtooth" pattern transmitted from a module with one open network circuit.

Other corruptions may be present when a module is intermittently powered up and down. The module on power up may initiate communication out of sync with other modules on the network causing momentary communication outages.

CAN MULTIPLEX MESSAGES

Possible Sources

1. Fuse
2. Wiring, terminals and connectors
3. PCM

1. Fuse
2. Wiring, terminals and connectors
3. ABS module

Possible Causes

1. Fuse
2. Wiring, terminals and connectors
3. RCM

1. Fuse
2. Wiring, terminals and connector
3. OCSM

1. Fuse
2. Wiring, terminals and connector
3. SASM

1. Fuse
2. Wiring, terminals and connector
3. IPC

1. Fuse
2. Wiring, terminals and connector
3. Information Center Module (ICM)

1. Fuse
2. Wiring, terminals and connector
3. BCM

1. Fuse
2. Wiring, terminals and connector
3. HVAC module

1. Fuse
2. Wiring, terminals and connector
3. ACM

1. Fuse
2. Wiring, terminals and connector
3. DSP

1. Fuse
2. Wiring, terminals and connector
3. DDM

1. Fuse
2. Wiring, terminals and connector
3. PDM

1. Fuse
2. Wiring, terminals and connector
3. Image Processing Module - B (IPM-B)

1. Fuse
2. Wiring, terminals and connector
3. Parking Aid Module (PAM)

1. Fuse
2. Wiring, terminals and connector
3. APIM

1. Fuse
2. Wiring, terminals and connector
3. FCIM

1. Fuse
2. Wiring, terminals and connector
3. RFA module

1. Fuse
2. Wiring, terminals and connector
3. TCM

1. Fuse
2. Wiring, terminals and connector
3. PSCM

1. Fuse
2. Wiring, terminals or connectors
3. ABS module
4. APIM
5. BCM
6. Information Center Module (ICM) (if equipped)
7. OCSM
8. Parking Aid Module (PAM)
9. PSCM
10. PCM
11. SASM
12. RCM
13. TCM

1. Fuse
2. Wiring, terminals or connectors
3. APIM (if equipped)
4. BCM
5. DDM
6. GPSM
7. HVAC Module
8. Image Processing Module-B (IPM-B)
9. IPC
10. PDM
11. RFA Module

1. Fuse
2. Wiring, terminals or connectors
3. ACM
4. APIM
5. DSP
6. IPC
7. FCDIM
8. FCIM

Scheme 15

1. Y1: CHECK THE INFOTAINMENT CONTROLLER AREA NETWORK (I-CAN) TERMINATION RESISTANCE Measure: Click to display connectors Positive Lead Measurement / Action Negative Lead C251-1 ohms C251-8 Is the resistance between 54 and 66 ohms? Yes: GO to Y2 No: GO to Y4
2. Y2 CHECK THE INFOTAINMENT CONTROLLER AREA NETWORK (I-CAN) (+) AND INFOTAINMENT CONTROLLER AREA NETWORK (I-CAN) (-) CIRCUITS FOR A SHORT TO GROUND Measure: Click to display connectors Positive Lead Measurement / Action Negative Lead C251-1 ohms - C251-8 ohms - Are the resistances greater than 10, 000 ohms? Yes: GO to Y3 No: GO to Y11
3. Y3 CHECK THE INFOTAINMENT CONTROLLER AREA NETWORK (I-CAN) (+) AND INFOTAINMENT CONTROLLER AREA NETWORK (I-CAN) (-) CIRCUITS FOR A SHORT TO VOLTAGE Ignition ON. Measure: Click to display connectors Positive Lead Measurement / Action Negative Lead C251-1 - C251-8 - Are the voltages greater than 6 volts? Yes: REPAIR the circuit in question. No: GO to Y12
4. Y4 CHECK THE INFOTAINMENT CONTROLLER AREA NETWORK (I-CAN) TERMINATION RESISTOR Measure: Click to display connectors Positive Lead Measurement / Action Negative Lead C251-1 ohms C251-8 Is the resistance between 108 and 132 ohms? Yes: GO to Y5 No: GO to Y8
5. Y5 CHECK THE INFOTAINMENT CONTROLLER AREA NETWORK (I-CAN) TERMINATION RESISTOR WITH THE IPC (INSTRUMENT PANEL CLUSTER) DISCONNECTED Disconnect: IPC. Measure: Click to display connectors Positive Lead Measurement / Action Negative Lead C251-1 ohms C251-8 Is the resistance between 108 and 132 ohms? Yes: GO to Y6 No: GO to Y7
6. Y6 CHECK THE INFOTAINMENT CONTROLLER AREA NETWORK (I-CAN) CIRCUITS BETWEEN THE IPC (INSTRUMENT PANEL CLUSTER) AND THE DLC (DATA LINK CONNECTOR) FOR AN OPEN Measure: Click to display connectors Positive Lead Measurement / Action Negative Lead C220-5 ohms C251-1 C220-4 ohms C251-8 Are the resistances less than 3 ohms? Yes: GO to Y22 No: REPAIR the circuit in question.
7. Y7 CHECK THE INFOTAINMENT CONTROLLER AREA NETWORK (I-CAN) CIRCUITS BETWEEN THE ACM (AUDIO FRONT CONTROL MODULE) AND THE DLC (DATA LINK CONNECTOR) FOR AN OPEN Disconnect: ACM C240A. Measure: Click to display connectors Positive Lead Measurement / Action Negative Lead C240A-14 ohms C251-1 C240A-15 ohms C251-8 Are the resistances less than 3 ohms? Yes: GO to Y19 No: REPAIR the circuit in question.
8. Y8 CHECK THE INFOTAINMENT CONTROLLER AREA NETWORK (I-CAN) (+) AND INFOTAINMENT CONTROLLER AREA NETWORK (I-CAN) (-) CIRCUITS FOR A SHORT TOGETHER Measure: Click to display connectors Positive Lead Measurement / Action Negative Lead C251-1 ohms C251-8 Is the resistance less than 3 ohms? Yes: GO to Y10 No: GO to Y9
9. Y9 CHECK THE INFOTAINMENT CONTROLLER AREA NETWORK (I-CAN) CIRCUITS BETWEEN THE IPC (INSTRUMENT PANEL CLUSTER) AND THE DLC (DATA LINK CONNECTOR) FOR AN OPEN Measure: Click to display connectors Positive Lead Measurement / Action Negative Lead C251-1 ohms C251-8 Is the resistance greater than 10, 000 ohms? Yes: REPAIR the DLC or REPAIR the circuit in question. No: A capacitor internal to a module can still be draining, causing irregular resistance readings. WAIT 5 minutes. REPEAT the pinpoint test.
10. Y10 CHECK THE INFOTAINMENT CONTROLLER AREA NETWORK (I-CAN) (+) AND INFOTAINMENT CONTROLLER AREA NETWORK (I-CAN) (-) CIRCUITS FOR A SHORT TOGETHER WITH MODULES DISCONNECTED Measure: Click to display connectors Positive Lead Measurement / Action Negative Lead C251-1 ohms C251-8 Disconnect modules one at a time until the resistance is greater than 5 ohms. APIM (if equipped) DSP C4326A (if equipped) ACM C240A FCIM (if equipped) FCDIM (if equipped) IPC Did the resistance change to greater than 5 ohms with one of the modules disconnected? Yes: For the APIM, GO to Y17 For the DSP, GO to Y18 For the ACM, GO to Y19 For the FCIM, GO to Y20 For the FCDIM, GO to Y21 For the IPC, GO to Y22 No: REPAIR the circuits in question.
11. Y11 CHECK THE INFOTAINMENT CONTROLLER AREA NETWORK (I-CAN) (+) AND INFOTAINMENT CONTROLLER AREA NETWORK (I-CAN) (-) CIRCUITS FOR A SHORT TO GROUND WITH THE MODULES DISCONNECTED Measure: Click to display connectors Positive Lead Measurement / Action Negative Lead C251-1 ohms - C251-8 ohms - Disconnect modules, one at a time until the resistance to ground is greater than 10, 000 ohms. APIM (if equipped) DSP C4326A (if equipped) ACM C240A FCIM (if equipped) FCDIM (if equipped) IPC Are the resistances greater than 10, 000 ohms? Yes: For the APIM, GO to Y17 For the DSP, GO to Y18 For the ACM, GO to Y19 For the FCIM, GO to Y20 For the FCDIM, GO to Y21 For the IPC, GO to Y22 No: REPAIR the circuit in question. CONNECT all modules.
12. Y12 CHECK FOR RESTORED COMMUNICATION WITH THE FCIM (FRONT CONTROLS INTERFACE MODULE) AND ACM (AUDIO FRONT CONTROL MODULE) DISABLED NOTE: When re-running the network test, close the network test application first or the screen display reverts back to the prior network test results. Disconnect: Body Control Module (BCM) fuse 79 (15A). Using a scan tool, perform the network test. Do all other Infotainment Controller Area Network (I-CAN) modules pass the network test? Yes: CONNECT all modules. If the vehicle is equipped with a FCIM, GO to Y13 If the vehicle is not equipped with a FCIM, GO to «Pinpoint Test K»(ref-515972-S26602083222012120400000) No: If the vehicle is equipped with an DSP, INSTALL the removed fuse. GO to Y14 If the vehicle is not equipped with an DSP, INSTALL the removed fuse. GO to Y15
13. Y13 CHECK FOR RESTORED COMMUNICATION WITH THE FCIM (FRONT CONTROLS INTERFACE MODULE) DISCONNECTED NOTE: When re-running the network test, close the network test application first or the screen display reverts back to the prior network test results. Disconnect: FCIM. Using a scan tool, perform the network test. Do all other Infotainment Controller Area Network (I-CAN) modules pass the network test? Yes: CONNECT all modules. GO to «Pinpoint Test S»(ref-515972-S00759391192012120400000) No: CONNECT all modules. GO to «Pinpoint Test K»(ref-515972-S26602083222012120400000)
14. Y14 CHECK FOR RESTORED NETWORK COMMUNICATION WITH THE DSP (AUDIO DIGITAL SIGNAL PROCESSING MODULE) DISABLED NOTE: When re-running the network test, close the network test application first or the screen display reverts back to the prior network test results. Disconnect: RJB fuse 23 (25A). Using a scan tool, perform the network test. Do all other modules pass the network test? Yes: INSTALL the removed fuse. GO to «Pinpoint Test L»(ref-515972-S21943226442012120400000) No: If the vehicle is equipped with SYNC®, GO to Y15 If the vehicle is not equipped with SYNC®, INSTALL the removed fuse. The Infotainment Controller Area Network (I-CAN) tests within specification. VERIFY the correct operation of the scan tool on a known good vehicle.
15. Y15 CHECK FOR RESTORED COMMUNICATION WITH THE APIM (ACCESSORY PROTOCOL INTERFACE MODULE) AND THE FCDIM (FRONT CONTROL/DISPLAY INTERFACE MODULE) DISABLED NOTE: When re-running the network test, close the network test application first or the screen display reverts back to the prior network test results. Disconnect: BCM fuse 67 (7.5A). Using a scan tool, perform the network test. Do all other Infotainment Controller Area Network (I-CAN) modules pass the network test? Yes: CONNECT all modules. If the vehicle is equipped with a APIM, GO to Y16 If the vehicle is not equipped with an APIM, GO to «Pinpoint Test D»(ref-515972-S14334958222012120400000) No: CONNECT all modules. The Infotainment Controller Area Network (I-CAN) tests within specification. VERIFY the correct operation of the scan tool on a known good vehicle.
16. Y16 CHECK FOR RESTORED COMMUNICATION WITH THE FCDIM (FRONT CONTROL/DISPLAY INTERFACE MODULE) DISCONNECTED NOTE: When re-running the network test, close the network test application first or the screen display reverts back to the prior network test results. Disconnect: FCDIM (if equipped). Using a scan tool, perform the network test. Do all other Infotainment Controller Area Network (I-CAN) modules pass the network test? Yes: CONNECT all modules. GO to «Pinpoint Test D»(ref-515972-S14334958222012120400000) No: CONNECT all modules. GO to «Pinpoint Test R»(ref-515972-S40555143972012120400000)
17. Y17 CHECK THE APIM (ACCESSORY PROTOCOL INTERFACE MODULE) FOR CORRECT OPERATION Ignition OFF. Disconnect and inspect the APIM connector. Repair: corrosion (install new connector or terminals - clean module pins) damaged or bent pins - install new terminals/pins pushed-out pins - install new pins as necessary Reconnect the APIM connector. Make sure it seats and latches correctly. Operate the system and determine if the concern is still present. Is the concern still present? Yes: CHECK OASIS for any applicable Technical Service Bulletins (TSBs). If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no Technical Service Bulletins (TSBs) address this concern, INSTALL a new APIM. If equipped with SYNC/AM/FM/CD, REFER to: «ACCESSORY PROTOCOL INTERFACE MODULE (APIM)»(ref-515932-S32782240822012120400000) . If equipped with Sony AM/FM/CD/SYNC, REFER to: «ACCESSORY PROTOCOL INTERFACE MODULE (APIM)»(ref-515933-S13494101232012120400000) . No: The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.
18. Y18 CHECK THE DSP (AUDIO DIGITAL SIGNAL PROCESSING MODULE) FOR CORRECT OPERATION Ignition OFF. Disconnect and inspect all the DSP connectors. Repair: corrosion (install new connector or terminals - clean module pins) damaged or bent pins - install new terminals/pins pushed-out pins - install new pins as necessary Reconnect the DSP connectors. Make sure they seat and latch correctly. Operate the system and determine if the concern is still present. Is the concern still present? Yes: CHECK OASIS for any applicable Technical Service Bulletins (TSBs). If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no Technical Service Bulletins (TSBs) address this concern, INSTALL a new DSP. REFER to: «AUDIO DIGITAL SIGNAL PROCESSING (DSP) MODULE»(ref-515933-S31695947082012120400000) . No: The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.
19. Y19 CHECK THE ACM (AUDIO FRONT CONTROL MODULE) FOR CORRECT OPERATION Ignition OFF. Disconnect and inspect all the ACM connectors. Repair: corrosion (install new connector or terminals - clean module pins) damaged or bent pins - install new terminals/pins pushed-out pins - install new pins as necessary Reconnect the ACM connectors. Make sure they seat and latch correctly. Operate the system and determine if the concern is still present. Is the concern still present? Yes: CHECK OASIS for any applicable Technical Service Bulletins (TSBs). If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no Technical Service Bulletins (TSBs) address this concern, INSTALL a new ACM. If equipped with AM/FM/CD, REFER to: «AUDIO FRONT CONTROL MODULE (ACM)»(ref-515931-S22291225992012120400000) . If equipped with SYNC/AM/FM/CD, REFER to: «AUDIO FRONT CONTROL MODULE (ACM)»(ref-515932-S19859685552012120400000) . If equipped with Sony AM/FM/CD/SYNC, REFER to: «AUDIO FRONT CONTROL MODULE (ACM)»(ref-515933-S34397221142012120400000) . No: The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.
20. Y20 CHECK THE FCIM (FRONT CONTROLS INTERFACE MODULE) FOR CORRECT OPERATION Ignition OFF. Disconnect and inspect the FCIM connector. Repair: corrosion (install new connector or terminals - clean module pins) damaged or bent pins - install new terminals/pins pushed-out pins - install new pins as necessary Reconnect the FCIM connector. Make sure it seats and latches correctly. Operate the system and determine if the concern is still present. Is the concern still present? Yes: CHECK OASIS for any applicable Technical Service Bulletins (TSBs). If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no Technical Service Bulletins (TSBs) address this concern, INSTALL a new FCIM. If equipped with AM/FM/CD, REFER to: «FRONT CONTROLS INTERFACE MODULE (FCIM)»(ref-515931-S01842134582012120400000) . If equipped with SYNC/AM/FM/CD, REFER to: «FRONT CONTROLS INTERFACE MODULE (FCIM)»(ref-515932-S30979992462012120400000) . If equipped with Sony AM/FM/CD/SYNC, REFER to: «FRONT CONTROLS INTERFACE MODULE (FCIM)»(ref-515933-S41535852092012120400000) . No: The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.
21. Y21 CHECK THE FCDIM (FRONT CONTROL/DISPLAY INTERFACE MODULE) FOR CORRECT OPERATION Ignition OFF. Disconnect and inspect the FCDIM connector. Repair: corrosion (install new connector or terminals - clean module pins) damaged or bent pins - install new terminals/pins pushed-out pins - install new pins as necessary Reconnect the FCDIM connector. Make sure it seats and latches correctly. Operate the system and determine if the concern is still present. Is the concern still present? Yes: CHECK OASIS for any applicable Technical Service Bulletins (TSBs). If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no Technical Service Bulletins (TSBs) address this concern, INSTALL a new FCDIM. If equipped with AM/FM/CD, REFER to: «FRONT CONTROL/DISPLAY INTERFACE MODULE (FCDIM)»(ref-515931-S02313177982012120400000) . If equipped with SYNC/AM/FM/CD, REFER to: «FRONT CONTROL/DISPLAY INTERFACE MODULE (FCDIM)»(ref-515932-S25274859672012120400000) . No: The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.
22. Y22 CHECK THE IPC (INSTRUMENT PANEL CLUSTER) FOR CORRECT OPERATION Ignition OFF. Disconnect and inspect the IPC connector. Repair: corrosion (install new connector or terminals - clean module pins) damaged or bent pins - install new terminals/pins pushed-out pins - install new pins as necessary Reconnect the IPC connector. Make sure it seats and latches correctly. Operate the system and determine if the concern is still present. Is the concern still present? Yes: CHECK OASIS for any applicable Technical Service Bulletins (TSBs). If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no Technical Service Bulletins (TSBs) address this concern, INSTALL a new IPC. REFER to: «INSTRUMENT PANEL CLUSTER (IPC)»(ref-515970-S21450118112012120400000) . No: The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.

1. Fuse
2. Wiring, terminals or connector
3. DLC
4. Scan tool