Pinpoint Test A: MECS Overheating

WARNING: This page is about a different car, the 2010 Mercury Mariner and 2010 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multi-meter probes.

A1 CHECK FOR DTCs
- Connect the scan tool.
- Enter the following diagnostic mode on the scan tool: RETRIEVE.
- Carry out the PCM on-demand self test.
- Are DTCs retrieved?
- Yes: REFER to INTRODUCTION -- HYBRID .
- No: GO to A2 .
A2 CHECK PDB FUSE 14 (10A)
- Check fuse: PDB 14 (10A).
- Is the fuse okay?
- Yes: GO to A3 .
- No: REPAIR circuit CB108 (GY/YE) for a short to ground. TEST the system for normal operation.
A3 CHECK THE MECS COOLANT PUMP AND WIRING FOR DAMAGE
- Disconnect: MECS Coolant Pump C1466.
- Check the MECS coolant pump, wiring and harness connector for:
  - pushed-out connector pins.
  - bent connector pins.
  - corrosion.
  - broken or missing wiring insulation.
- Is the MECS coolant pump relay, harness connector and wiring OK?
- Yes: GO to A4 .
- No: REPAIR or INSTALL new components as necessary. TEST the system for normal operation.
A4 CHECK THE MECS PUMP RELAY (PDB RELAY 31D) HARNESS CONNECTOR AND WIRING
- Disconnect: PDB Relay 31D.
- Check the MECS coolant pump relay (PDB relay 31D) harness connector and wiring for:
  - pushed-out connector pins.
  - bent connector pins.
  - corrosion.
  - broken or missing wiring insulation.
- Is the MECS coolant pump relay (PDB relay 31D) harness connector and wiring OK?
- Yes: GO to A5 .
- No: REPAIR or INSTALL new components as necessary. TEST the system for normal operation.
A5 CHECK THE MECS COOLANT PUMP RELAY (PDB RELAY 31D)
- Carry out the relay component test.
  Refer to appropriate SYSTEM WIRING DIAGRAMS article for component testing.
- Is the MECS pump relay (PDB relay 31D) OK?
- Yes: GO to A6 .
- No: INSTALL a new MECS pump relay (PDB relay 31D). TEST the system for normal operation.
A6 CHECK CIRCUIT CB108 (GY/YE) FOR AN OPEN
- Measure the resistance between MECS coolant pump C1466-2, harness side and PDB MECS coolant pump relay 31D, circuit CB108 (GY/YE) socket.
  
  Fig 1: Checking Circuit
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes: GO to A7 .
- No: REPAIR the circuit. TEST the system for normal operation.
A7 CHECK CIRCUIT GD120 (BK/GN) FOR AN OPEN
- Measure the resistance between MECS coolant pump C1466-1, circuit GD120 (BK/GN), harness side and ground.
  
  Fig 2: Measuring Resistance Between MECS Coolant Pump 1466-1 Circuit GD120 (BK/GN) Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes: INSTALL a new MECS coolant pump. REFER to MOTOR ELECTRONICS PUMP . TEST the system for normal operation.
- No: REPAIR the circuit. TEST the system for normal operation.