Pinpoint Test K: THE REAR ELECTRONIC MODULE (REM) DOES NOT RESPOND TO THE DIAGNOSTIC TOOL

WARNING: This page is about a different car, the 2005 Lincoln LS. However, it is still accessible from the selected car via links, so may be relevant.

K1 CHECK THE REM C420B FOR DAMAGE
- Key in OFF position.
- Disconnect: REM C420b.
- Inspect the REM C420b for damage.
- Is the REM C420b OK?
- Yes : GO to K2.
- No : REPAIR the REM C420b as necessary. TEST the system for normal operation.
K2 CHECK FOR AN OPEN BETWEEN THE DATA LINK CONNECTOR (DLC) C251 AND THE REM C420B
- Measure the resistance between the REM C420b-1, circuit 4-EG12 (GY/WH), harness side and the DLC C251-2, circuit 4-EG7 (GY/RD), harness side.
  
  Fig 1: Measuring The Resistance Between The REM C420b-1, Circuit 4-EG12 (GY/WH), Harness Side And The DLC C251-2, Circuit 4-EG7 (GY/RD), Harness Side
  Courtesy of FORD MOTOR CO.
- Measure the resistance between the REM C420b-2, circuit 5-EG12 (BU/OG), harness side and the DLC C251-10, circuit 5-EG7 (BU/RD), harness side.
  
  Fig 2: Measuring The Resistance Between The REM C420b-2, Circuit 5-EG12 (BU/OG), Harness Side And The DLC C251-10, Circuit 5-EG7 (BU/RD), Harness Side
  Courtesy of FORD MOTOR CO.
- Are the resistances less than 5 ohms?
- Yes : GO to K7.
- No : GO to K3.
K3 CHECK FOR AN OPEN BETWEEN THE INTERIOR AUXILIARY JUNCTION BOX (AJB) C283B AND THE REM C420B
- Disconnect: Interior AJB C283b.
- Measure the resistance between the REM C420b-1, circuit 4-EG12 (GY/WH), harness side and the interior AJB C283b-16, circuit 4-EG12 (GY/WH), harness side.
  
  Fig 3: Measuring The Resistance Between The REM C420b-1, Circuit 4-EG12 (GY/WH), Harness Side And The Interior AJB C283b-16, Circuit 4-EG12 (GY/WH), Harness Side
  Courtesy of FORD MOTOR CO.
- Measure the resistance between the REM C420b-2, circuit 5-EG12 (BU/OG), harness side and the interior AJB C283b-12, circuit 5-EG12 (BU/OG), harness side.
  
  Fig 4: Measuring The Resistance Between The REM C420b-2, Circuit 5-EG12 (BU/OG), Harness Side And The Interior AJB C283b-12, Circuit 5-EG12 (BU/OG), Harness Side
  Courtesy of FORD MOTOR CO.
- Are the resistances less than 5 ohms?
- Yes : GO to K4.
- No : REPAIR the circuit in question. TEST the system for normal operation.
K4 CHECK FOR AN OPEN BETWEEN THE INTERIOR AJB C283B AND THE INTERIOR AJB C283D
- Disconnect: Interior AJB C283d.
- Measure the resistance between the interior AJB C283d-16, component side and the interior AJB C283b-16, component side.
  
  Fig 5: Measuring The Resistance Between The Interior AJB C283d-16, Component Side And The Interior AJB C283b-16, Component Side
  Courtesy of FORD MOTOR CO.
- Measure the resistance between the interior AJB C283d-12, component side and the interior AJB C283b-12, component side.
  
  Fig 6: Measuring The Resistance Between The Interior AJB C283d-12, Component Side And The Interior AJB C283b-12, Component Side
  Courtesy of FORD MOTOR CO.
- Are the resistances less than 5 ohms?
- Yes : GO to K5.
- No : INSTALL a new interior AJB. TEST the system for normal operation.
K5 CHECK FOR AN OPEN BETWEEN THE INTERIOR AJB C283D AND JOINT CONNECTOR NO. 4 C223
- Disconnect: Joint Connector No. 4 C223.
- Measure the resistance between the interior AJB C283d-16, circuit 4-EG1 (GY/RD), harness side and joint connector No. 4 C223-12, circuit 4-EG1 (GY/RD), harness side.
  
  Fig 7: Measuring Resistance Between Interior AJB C283d-16, Circuit 4-EG1 (GY/RD), Harness Side And Joint Connector No. 4 C223-12, Circuit 4-EG1 (GY/RD), Harness Side
  Courtesy of FORD MOTOR CO.
- Measure the resistance between the interior AJB C283d-12, circuit 5-EG1 (BU/RD), harness side and joint connector No. 4 C223-11, circuit 5-EG1 (BU/RD), harness side.
  
  Fig 8: Measuring Resistance Between Interior AJB C283d-12, Circuit 5-EG1 (BU/RD), Harness Side And Joint Connector No. 4 C223-11, Circuit 5-EG1 (BU/RD), Harness Side
  Courtesy of FORD MOTOR CO.
- Are the resistances less than 5 ohms?
- Yes : GO to K6.
- No : REPAIR the circuit in question. CARRY OUT the diagnostic tool data link test.
K6 CHECK JOINT CONNECTOR NO. 4 FOR AN OPEN
- Measure the resistance between joint connector No. 4 C223-12, component side and joint connector No. 4 C223-14, component side.
  
  Fig 9: Measuring The Resistance Between Joint Connector No. 4 C223-12, Component Side And Joint Connector No. 4 C223-14, Component Side
  Courtesy of FORD MOTOR CO.
- Measure the resistance between joint connector No. 4 C223-9, component side and joint connector No. 4 C223-11, component side.
  
  Fig 10: Measuring The Resistance Between Joint Connector No. 4 C223-9, Component Side And Joint Connector No. 4 C223-11, Component Side
  Courtesy of FORD MOTOR CO.
- Are the resistances less than 5 ohms?
- Yes : REPAIR the circuit in question between the DLC C251 and joint connector No. 4 C223. CARRY OUT the diagnostic tool data link test.
- No : REPAIR joint connector No. 4 C223. TEST the system for normal operation.
K7 CHECK FOR CORRECT REM OPERATION
- Disconnect all the REM connectors.
- Check for:
- corrosion
- push-out pins
- Connect all the REM 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 REM. REFER to MULTIFUNCTION ELECTRONIC MODULES . TEST the system for normal operation. CARRY OUT the diagnostic tool data link test.
- 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 self-test.