Pinpoint Test N: The Rear Entertainment Module (RETM) Does Not Respond To The Scan Tool

Refer to appropriate SYSTEM WIRING DIAGRAMS article, Module Communications Network for schematic and connector information.

Normal Operation 

The rear entertainment module (RETM) communicates with the scan tool through the medium speed controller area network (MS-CAN). Circuits VDB06 (GY/OG) (MS-CAN +) and VDB07 (VT/OG) (MS-CAN -) provide the network connection to the RETM. The RETM shares the MS-CAN with the instrument cluster (IC), the accessory protocol interface module (APIM), the smart junction box (SJB), the HVAC module (if equipped), the audio control module (ACM), the audio digital signal processing (DSP) module (if equipped), the satellite digital audio receiver system (SDARS) module (if equipped), the driver seat module (DSM) (if equipped), the parking aid module (PAM) (if equipped), the liftgate/trunk module (LTM) (if equipped) and the dual climate control seat module (DCSM) (if equipped). Voltage for the RETM is provided by circuit SBP03 (BU/RD). Circuit GD114 (BK/BU) provides ground.

This pinpoint test is intended to diagnose the following:

• Fuse
• Wiring, terminals or connectors
• RETM

PINPOINT TEST N: THE REAR ENTERTAINMENT MODULE (RETM) DOES NOT RESPOND TO THE SCAN TOOL 

1. N1 CHECK THE RETM VOLTAGE SUPPLY CIRCUIT FOR AN OPEN 
   • Key in OFF position.
   • Disconnect: RETM C949
   • Key in ON position.
   Fig 1: Measuring Voltage
   Courtesy of FORD MOTOR CO.
   • Measure the voltage between the RETM C949-16, circuit SBP03 (BU/RD), harness side and ground.
   • Is the voltage greater than 10 volts? 
   1. YES  : Go to  N2.
   2. NO  : VERIFY the SJB fuse 3 (15A) is OK. If OK, REPAIR the circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.
2. N2 CHECK THE RETM GROUND CIRCUIT FOR AN OPEN 
   • Key in OFF position.
   Fig 2: Measuring Resistance
   Courtesy of FORD MOTOR CO.
   • Measure the resistance between the RETM C949-1, circuit GD114 (BK/BU), harness side and ground.
   • Is the resistance less than 5 ohms? 
   1. YES  : Go to  N3.
   2. NO  : REPAIR the circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.
3. N3 CHECK THE MS-CAN CIRCUITS BETWEEN THE RETM AND THE DATA LINK CONNECTOR (DLC) FOR AN OPEN 
   Fig 3: Measuring Resistance
   Courtesy of FORD MOTOR CO.
   • Measure the resistance between the RETM C949-8, circuit VDB06 (GY/OG), harness side and the DLC C251-3, circuit VDB06 (GY/OG), harness side.
   Fig 4: Measuring Resistance
   Courtesy of FORD MOTOR CO.
   • Measure the resistance between the RETM C949-7, circuit VDB07 (VT/OG), harness side and the DLC C251-11, circuit VDB07 (VT/OG), harness side.
   • Are the resistances less than 5 ohms? 
   1. YES  : Go to  N4.
   2. NO  : REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.
4. N4 CHECK FOR CORRECT RETM OPERATION 
   • Disconnect the RETM connector.
   • Check for:
     • corrosion
     • damaged pins
     • pushed-out pins
   • Connect the RETM connector and make sure it seats correctly.
   • Operate the system and verify the concern is still present.
   • Is the concern still present? 
   1. YES  : INSTALL a new RETM. REFER to INFORMATION AND ENTERTAINMENT SYSTEMS article. CLEAR the DTCs. REPEAT the network test with the scan tool. TEST the system for normal operation.
   2. 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.