Pinpoint Tests

Transaxle Cooling

Pinpoint Tests

Pinpoint Test A: Motor Electronics Cooling System (MECS) Overheating

Refer to Wiring Diagram Set 54 (Escape/Mariner, Escape Hybrid/Mariner Hybrid), Climate Control for schematic and connector information. Diagrams By Number

Normal Operation

The Motor Electronics Cooling System (MECS) pump is electrically driven and controlled by the PCM through the MECS pump relay. The PCM energizes the MECS pump relay by pulling the MECS pump output to ground when the ignition is in the ON position.

This pinpoint test is intended to diagnose the following:
- Power Distribution Box (PDB) fuse 14 (10A)
- MECS coolant pump
- Wiring
- MECS coolant pump relay


PINPOINT TEST A: MECS OVERHEATING

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

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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 Computers and Control Systems Information.

No
GO to A2.

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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.

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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.

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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.

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A5 CHECK THE MECS COOLANT PUMP RELAY (PDB RELAY 31D)

- Carry out the relay component test.

- 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.

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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.





- Is the resistance less than 5 ohms?

Yes
GO to A7.

No
REPAIR the circuit. TEST the system for normal operation.

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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.





- Is the resistance less than 5 ohms?

Yes
INSTALL a new MECS coolant pump. REFER to Motor Electronics Pump Motor Electronics Pump. TEST the system for normal operation.

No
REPAIR the circuit. TEST the system for normal operation.

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