Part 2
Communications Network
Pinpoint Test U: No Medium Speed Controller Area Network (MS-CAN) Communication, All Modules Are Not Responding
Refer to Wiring Diagram Set 14, Module Communications Network for schematic and connector information Electrical Diagrams.
Normal Operation
The Medium Speed Controller Area Network (MS-CAN) uses an unshielded twisted pair cable, circuits VDB06 (GY/OG) and VDB07 (VT/OG) provide the network connection to all modules on the network.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Audio Control Module (ACM)
- Accessory Protocol Interface Module (APIM)
- Audio Digital Signal Processing (DSP) module (if equipped)
- Audio Rear Control Unit (RCU) module (if equipped)
- Dual Climate Controlled Seat Module (DCSM) (if equipped)
- Driver Seat Module (DSM) (if equipped)
- Global Positioning System Module (GPSM)
- HVAC module (if equipped)
- Instrument Cluster (IC)
- Liftgate/Trunk Module (LTM) (if equipped)
- Parking Aid Module (PAM) (if equipped)
- Power Running Board (PRB) module (if equipped)
- Satellite Digital Audio Receiver System (SDARS) module (if equipped)
- Smart Junction Box (SJB)
- Data Link Connector (DLC)
U35 CHECK THE MS-CAN (Medium Speed Controller Area Network) (+) AND MS-CAN (Medium Speed Controller Area Network) (-) CIRCUITS FOR A SHORT TO GROUND WITH THE ACM (Audio Control Module) DISCONNECTED
- Disconnect: ACM (Audio Control Module) C240B.
- Measure the resistance between the DLC (Data Link Connector) C251-3, circuit VDB06 (GY/OG), harness side and ground; and between the DLC (Data Link Connector) C251-11, circuit VDB07 (VT/OG), harness side and ground.
Are the resistances greater than 1,000 ohms?
Yes
CONNECT all modules. CONNECT the negative battery cable. GO to U60.
No
GO to U36.
U36 VERIFY VEHICLE EQUIPMENT - AUDIO DSP (Digital Signal Processing) MODULE
- Inspect the vehicle for an audio DSP (Digital Signal Processing) module.
Is the vehicle equipped with an audio DSP (Digital Signal Processing) module?
Yes
GO to U37.
No
GO to U38.
U37 CHECK THE MS-CAN (Medium Speed Controller Area Network) (+) AND MS-CAN (Medium Speed Controller Area Network) (-) CIRCUITS FOR A SHORT TO GROUND WITH THE AUDIO DSP (Digital Signal Processing) MODULE DISCONNECTED
- Disconnect: Audio DSP (Digital Signal Processing) Module C2364C.
- Measure the resistance between the DLC (Data Link Connector) C251-3, circuit VDB06 (GY/OG), harness side and ground; and between the DLC (Data Link Connector) C251-11, circuit VDB07 (VT/OG), harness side and ground.
Are the resistances greater than 1,000 ohms?
Yes
CONNECT all modules. CONNECT the negative battery cable. GO to U61.
No
GO to U38.
U38 VERIFY VEHICLE EQUIPMENT - HVAC MODULE
- Inspect the vehicle for an HVAC module.
Is the vehicle equipped with an HVAC module?
Yes
GO to U39.
No
GO to U40.
U39 CHECK THE MS-CAN (Medium Speed Controller Area Network) (+) AND MS-CAN (Medium Speed Controller Area Network) (-) CIRCUITS FOR A SHORT TO GROUND WITH THE HVAC MODULE DISCONNECTED
- Disconnect: HVAC Module C228A (EATC (Electronic Automatic Temperature Control)) or C2357A (EMTC (Electronic Manual Temperature Control)).
- Measure the resistance between the DLC (Data Link Connector) C251-3, circuit VDB06 (GY/OG), harness side and ground; and between the DLC (Data Link Connector) C251-11, circuit VDB07 (VT/OG), harness side and ground.
Are the resistances greater than 1,000 ohms?
Yes
CONNECT all modules. CONNECT the negative battery cable. GO to U62.
No
GO to U40.
U40 VERIFY VEHICLE EQUIPMENT - APIM (Accessory Protocol Interface Module)
- Inspect the vehicle for an Accessory Protocol Interface Module (APIM).
Is the vehicle equipped with an APIM (Accessory Protocol Interface Module)?
Yes
GO to U41.
No
GO to U42.
U41 CHECK THE MS-CAN (Medium Speed Controller Area Network) (+) AND MS-CAN (Medium Speed Controller Area Network) (-) CIRCUITS FOR A SHORT TO GROUND WITH THE APIM (Accessory Protocol Interface Module) DISCONNECTED
- Disconnect: APIM (Accessory Protocol Interface Module) C3342.
- Measure the resistance between the DLC (Data Link Connector) C251-3, circuit VDB06 (GY/OG), harness side and ground; and between the DLC (Data Link Connector) C251-11, circuit VDB07 (VT/OG), harness side and ground.
Are the resistances greater than 1,000 ohms?
Yes
CONNECT all modules. CONNECT the negative battery cable. GO to U63.
No
GO to U42.
U42 VERIFY VEHICLE EQUIPMENT - AUDIO RCU (Rear Control Unit) MODULE
- Inspect the vehicle for an audio Rear Control Unit (RCU) module.
Is the vehicle equipped with an audio RCU (Rear Control Unit) module?
Yes
GO to U43.
No
GO to U44.
U43 CHECK THE MS-CAN (Medium Speed Controller Area Network) (+) AND MS-CAN (Medium Speed Controller Area Network) (-) CIRCUITS FOR A SHORT TO GROUND WITH THE AUDIO RCU (Rear Control Unit) MODULE DISCONNECTED
- Disconnect: Audio RCU (Rear Control Unit) module C3077.
- Measure the resistance between the DLC (Data Link Connector) C251-3, circuit VDB06 (GY/OG), harness side and ground; and between the DLC (Data Link Connector) C251-11, circuit VDB07 (VT/OG), harness side and ground.
Are the resistances greater than 1,000 ohms?
Yes
CONNECT all modules. CONNECT the negative battery cable. GO to U64.
No
GO to U44.
U44 VERIFY VEHICLE EQUIPMENT - DSM (Driver Seat Module)
- Inspect the vehicle for a Driver Seat Module (DSM).
Is the vehicle equipped with a DSM (Driver Seat Module)?
Yes
GO to U45.
No
GO to U46.
U45 CHECK THE MS-CAN (Medium Speed Controller Area Network) (+) AND MS-CAN (Medium Speed Controller Area Network) (-) CIRCUITS FOR A SHORT TO GROUND WITH THE DSM (Driver Seat Module) DISCONNECTED
- Disconnect: DSM (Driver Seat Module) C341D.
- Measure the resistance between the DLC (Data Link Connector) C251-3, circuit VDB06 (GY/OG), harness side and ground; and between the DLC (Data Link Connector) C251-11, circuit VDB07 (VT/OG), harness side and ground.
Are the resistances greater than 1,000 ohms?
Yes
CONNECT all modules. CONNECT the negative battery cable. GO to U65.
No
GO to U46.
U46 VERIFY VEHICLE EQUIPMENT - DCSM (Dual Climate Controlled Seat Module)
- Inspect the vehicle for a Dual Climate Controlled Seat Module (DCSM).
Is the vehicle equipped with a DCSM (Dual Climate Controlled Seat Module)?
Yes
GO to U47.
No
GO to U48.
U47 CHECK THE MS-CAN (Medium Speed Controller Area Network) (+) AND MS-CAN (Medium Speed Controller Area Network) (-) CIRCUITS FOR A SHORT TO GROUND WITH THE DCSM (Dual Climate Controlled Seat Module) DISCONNECTED
- Disconnect: DCSM (Dual Climate Controlled Seat Module) C3265C.
- Measure the resistance between the DLC (Data Link Connector) C251-3, circuit VDB06 (GY/OG), harness side and ground; and between the DLC (Data Link Connector) C251-11, circuit VDB07 (VT/OG), harness side and ground.
Are the resistances greater than 1,000 ohms?
Yes
CONNECT all modules. CONNECT the negative battery cable. GO to U66.
No
GO to U48.
U48 VERIFY VEHICLE EQUIPMENT - SDARS (Satellite Digital Audio Receiver System) MODULE
- Inspect the vehicle for a Satellite Digital Audio Receiver System (SDARS) module.
Is the vehicle equipped with a SDARS (Satellite Digital Audio Receiver System) module?
Yes
GO to U49.
No
GO to U50.
U49 CHECK THE MS-CAN (Medium Speed Controller Area Network) (+) AND MS-CAN (Medium Speed Controller Area Network) (-) CIRCUITS FOR A SHORT TO GROUND WITH THE SDARS (Satellite Digital Audio Receiver System) MODULE DISCONNECTED
- Disconnect: SDARS (Satellite Digital Audio Receiver System) Module C3290.
- Measure the resistance between the DLC (Data Link Connector) C251-3, circuit VDB06 (GY/OG), harness side and ground; and between the DLC (Data Link Connector) C251-11, circuit VDB07 (VT/OG), harness side and ground.
Are the resistances greater than 1,000 ohms?
Yes
CONNECT all modules. CONNECT the negative battery cable. GO to U67.
No
GO to U50.
U50 VERIFY VEHICLE EQUIPMENT - PRB (Power Running Board) MODULE
- Inspect the vehicle for a PRB (Power Running Board) module.
Is the vehicle equipped with a PRB (Power Running Board) module?
Yes
GO to U51.
No
GO to U52.
U51 CHECK THE MS-CAN (Medium Speed Controller Area Network) (+) AND MS-CAN (Medium Speed Controller Area Network) (-) CIRCUITS FOR A SHORT TO GROUND WITH THE PRB (Power Running Board) MODULE DISCONNECTED
- Disconnect: PRB (Power Running Board) Module C3313B.
- Measure the resistance between the DLC (Data Link Connector) C251-3, circuit VDB06 (GY/OG), harness side and ground; and between the DLC (Data Link Connector) C251-11, circuit VDB07 (VT/OG), harness side and ground.
Are the resistances greater than 1,000 ohms?
Yes
CONNECT all modules. CONNECT the negative battery cable. GO to U68.
No
GO to U52.
U52 VERIFY VEHICLE EQUIPMENT - PAM (Parking Aid Module)
- Inspect the vehicle for a PAM (Parking Aid Module).
Is the vehicle equipped with a PAM (Parking Aid Module)?
Yes
GO to U53.
No
GO to U54.
U53 CHECK THE MS-CAN (Medium Speed Controller Area Network) (+) AND MS-CAN (Medium Speed Controller Area Network) (-) CIRCUITS FOR A SHORT TO GROUND WITH THE PAM (Parking Aid Module) DISCONNECTED
- Disconnect: PAM (Parking Aid Module) C4226 (Expedition) or C4014A (Navigator).
- Measure the resistance between the DLC (Data Link Connector) C251-3, circuit VDB06 (GY/OG), harness side and ground; and between the DLC (Data Link Connector) C251-11, circuit VDB07 (VT/OG), harness side and ground.
Are the resistances greater than 1,000 ohms?
Yes
CONNECT all modules. CONNECT the negative battery cable. GO to U69.
No
GO to U54.
U54 VERIFY VEHICLE EQUIPMENT - GPSM (Global Positioning System Module)
- Inspect the vehicle for a GPSM (Global Positioning System Module).
Is the vehicle equipped with a GPSM (Global Positioning System Module)?
Yes
GO to U55.
No
GO to U56.
U55 CHECK THE MS-CAN (Medium Speed Controller Area Network) (+) AND MS-CAN (Medium Speed Controller Area Network) (-) CIRCUITS FOR A SHORT TO GROUND WITH THE GPSM (Global Positioning System Module) DISCONNECTED
- Disconnect: GPSM (Global Positioning System Module) C2398.
- Measure the resistance between the DLC (Data Link Connector) C251-3, circuit VDB06 (GY/OG), harness side and ground; and between the DLC (Data Link Connector) C251-11, circuit VDB07 (VT/OG), harness side and ground.
Are the resistances greater than 1,000 ohms?
Yes
GO to U56.
No
CONNECT all modules. CONNECT the negative battery cable. GO to U71.
U56 VERIFY VEHICLE EQUIPMENT - LTM (Liftgate/Trunk Module)
- Inspect the vehicle for an LTM (Liftgate/Trunk Module).
Is the vehicle equipped with an LTM (Liftgate/Trunk Module)?
Yes
GO to U57.
No
REPAIR the circuit in question. CONNECT all modules. CONNECT the negative battery cable. CLEAR the DTCs. REPEAT the network test with the scan tool.
U57 CHECK THE MS-CAN (Medium Speed Controller Area Network) (+) AND MS-CAN (Medium Speed Controller Area Network) (-) CIRCUITS FOR A SHORT TO GROUND WITH THE LTM (Liftgate/Trunk Module) DISCONNECTED
- Disconnect: LTM (Liftgate/Trunk Module) C4174B.
- Measure the resistance between the DLC (Data Link Connector) C251-3, circuit VDB06 (GY/OG), harness side and ground; and between the DLC (Data Link Connector) C251-11, circuit VDB07 (VT/OG), harness side and ground.
Are the resistances greater than 1,000 ohms?
Yes
CONNECT all modules. CONNECT the negative battery cable. GO to U70.
No
REPAIR the circuit in question. CONNECT all modules. CONNECT the negative battery cable. CLEAR the DTCs. REPEAT the network test with the scan tool.
U58 CHECK FOR CORRECT SJB (Smart Junction Box) OPERATION
- Disconnect all the SJB (Smart Junction Box) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB (Smart Junction Box) connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new SJB (Smart Junction Box). CLEAR the DTCs. REPEAT the network test with the scan tool.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.
U59 CHECK FOR CORRECT IC (Instrument Cluster) OPERATION
- Disconnect the IC (Instrument Cluster) connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the IC (Instrument Cluster) connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new IC (Instrument Cluster). CLEAR the DTCs. REPEAT the network test with the scan tool.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.
U60 CHECK FOR CORRECT ACM (Audio Control Module) OPERATION
- Disconnect all the ACM (Audio Control Module) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the ACM (Audio Control Module) connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new ACM (Audio Control Module). CLEAR the DTCs. REPEAT the network test with the scan tool.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.
U61 CHECK FOR CORRECT AUDIO DSP (Digital Signal Processing) MODULE OPERATION
- Disconnect all the audio DSP (Digital Signal Processing) module connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the audio DSP (Digital Signal Processing) module connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new audio DSP (Digital Signal Processing) module. CLEAR the DTCs. REPEAT the network test with the scan tool.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.
U62 CHECK FOR CORRECT HVAC MODULE OPERATION
- Disconnect all the HVAC module connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the HVAC module connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new HVAC module. CLEAR the DTCs. REPEAT the network test with the scan tool.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.
U63 CHECK FOR CORRECT APIM (Accessory Protocol Interface Module) OPERATION
- Disconnect the APIM (Accessory Protocol Interface Module) connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the APIM (Accessory Protocol Interface Module) connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new APIM (Accessory Protocol Interface Module). CLEAR the DTCs. REPEAT the network test with the scan tool.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.
U64 CHECK FOR CORRECT AUDIO RCU (Rear Control Unit) MODULE OPERATION
- Disconnect the audio RCU (Rear Control Unit) module connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the audio RCU (Rear Control Unit) module connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new audio RCU (Rear Control Unit) module. CLEAR the DTCs. REPEAT the network test with the scan tool. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.
U65 CHECK FOR CORRECT DSM (Driver Seat Module) OPERATION
- Disconnect all the DSM (Driver Seat Module) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the DSM (Driver Seat Module) connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new DSM (Driver Seat Module). CLEAR the DTCs. REPEAT the network test with the scan tool.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.
U66 CHECK FOR CORRECT DCSM (Dual Climate Controlled Seat Module) OPERATION
- Disconnect all the DCSM (Dual Climate Controlled Seat Module) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the DCSM (Dual Climate Controlled Seat Module) connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new DCSM (Dual Climate Controlled Seat Module). CLEAR the DTCs. REPEAT the network test with the scan tool.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.
U67 CHECK FOR CORRECT SDARS (Satellite Digital Audio Receiver System) MODULE OPERATION
- Disconnect the SDARS (Satellite Digital Audio Receiver System) module connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the SDARS (Satellite Digital Audio Receiver System) module connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new SDARS (Satellite Digital Audio Receiver System) module. CLEAR the DTCs. REPEAT the network test with the scan tool.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.
U68 CHECK FOR CORRECT PRB (Power Running Board) MODULE OPERATION
- Disconnect all the PRB (Power Running Board) module connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the PRB (Power Running Board) module connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new PRB (Power Running Board) module. CLEAR the DTCs. REPEAT the network test with the scan tool.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.
U69 CHECK FOR CORRECT PAM (Parking Aid Module) OPERATION
- Disconnect all the PAM (Parking Aid Module) connector(s).
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the PAM (Parking Aid Module) connector(s) and make sure they seat correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new PAM (Parking Aid Module). CLEAR the DTCs. REPEAT the network test with the scan tool.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.
U70 CHECK FOR CORRECT LTM (Liftgate/Trunk Module) OPERATION
- Disconnect all the LTM (Liftgate/Trunk Module) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the LTM (Liftgate/Trunk Module) connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new LTM (Liftgate/Trunk Module). CLEAR the DTCs. REPEAT the network test with the scan tool.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.
U71 CHECK FOR CORRECT GPSM (Global Positioning System Module) OPERATION
- Disconnect: Disconnect the GPSM (Global Positioning System Module) connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the DSM (Driver Seat Module) connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new GPSM (Global Positioning System Module).
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.