Pinpoint Test K: The Remote Keyless Entry (RKE) Keypad Illumination Is Inoperative

WARNING: This page is about a different car, the 2006 Mercury Grand Marquis and 2006 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION: Use the correct probe adaptor(s) when making measurements. Failure to use the correct probe adaptor(s) may damage the connector.

K1 CHECK FOR VOLTAGE TO THE RKE KEYPAD
- Disconnect: RKE Keypad C530.
- Measure the voltage between the RKE keypad C530-2, circuit 1523 (DG), harness side and ground.
  
  Fig 1: Checking For Voltage To The RKE Keypad
  Courtesy of FORD MOTOR CO.
- Is voltage present?
Yes : GO to K2.

No : REPAIR the circuit.
K2 CHECK CIRCUIT 66 (LB) FOR GROUND
- Enter the following diagnostic mode on the diagnostic tool: DDM active command for KEYPAD BACKLIGHTING.
- Measure the resistance between the RKE keypad C530-5, circuit 66 (LB), harness side and ground.
  
  Fig 2: Checking Circuit 66 (LB) For Ground
  Courtesy of FORD MOTOR CO.
- Trigger the DDM active command for KEYPAD BACKLIGHTING ON while observing the resistance reading.
- Is the resistance less than 5 ohms?
Yes : INSTALL a new RKE keypad. REFER to REMOTE KEYLESS ENTRY KEYPAD. TEST the system for normal operation.

No : GO to K3.
K3 CHECK CIRCUIT 66 (LB) FOR AN OPEN
- Disconnect: DDM C501a.
- Measure the resistance between the DDM C501a-26, circuit 66 (LB), harness side and the RKE keypad C530-5, circuit 66 (LB), harness side.
  
  Fig 3: Checking Circuit 66 (LB) For An Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to K4.

No : REPAIR the circuit. TEST the system for normal operation.
K4 CHECK THE DDM FOR CORRECT OPERATION
- Disconnect all DDM connectors.
- Check for:
  - corrosion
  - pushed-out pins
- Connect all DDM 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 DDM. REFER to MULTIFUNCTION ELECTRONIC MODULES . PROGRAM all the RKE transmitters. REFER to REMOTE KEYLESS ENTRY TRANSMITTER PROGRAMMING. CLEAR the DTCs. REPEAT the self-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.