2005-2008 Ford Escape and 2006-2008 Mercury Mariner, Hybrid Electric Water Pump Diagnostic Procedure and Replacement

Overheating condition for Hybrid vehicles. This condition may exhibit a Red Triangle Light (“Stop Safely Light” or “High Motor Temperature") and/or codes indicating a transaxle over-temperature. Result in reduced power, as the system activates fail-safe operation.


Today’s vehicle manufacturers rely more on hybrid technology to meet federal emission standards but this sophisticated technology creates new challenges. Something as elementary as a water pump that once simply cooled the engine, is now also responsible for cooling the massive batteries used in today’s hybrid vehicles. A TechSmart™ hybrid electric water pump offers today’s technician a complete solution for replacing the failed OE water pump that can cause a hybrid vehicle’s battery to overheat.


Ford has issued a few Technical Service Bulletin, the lastest being 08-24-5, issued on December 8, 2008.


Superseding Bulletin 08-15-1, date of issue August 4, 2008.
Other related reference numbers: 05-23-6, 06-1-1, 06-11-10, 06-13-1, 06-26-11, 07-13-8, 07-23-2, 07-2-8, 08-24-5, 08-3-8, 08-4-16


The codes that may be set P1A0E, P1A0F, POA3C, POPA3E, POA7A, POA7C, and P1A0D.


Before condemning the Motor Electronics Cooling System (“MECS”). Check for engine coolant system loss or base engine overheating concerns, follow normal diagnosis in cases of engine overheating. Once you verify engine cooling systems are correct (fluid levels and no leaks), you are ready to move on to the MECS pump diagnostic procedure.


Is the electric pump running?


If so, verify the coolant flow into the MECS reservoir. If there is no flow check to see that you don’t have any hoses that are pinched or twisted.


If the pump is not running, tap on housing and listen for the pump to turn on. If the pump turns on, replace the pump.


If tapping on the pump does not turn the pump on, verify the connector has voltage.


If voltage is present double-check that the connector is fully seated in the pump, before replacing the pump.



The MECS can only be accessed from under the vehicle. The electric pump is located on the core support, below the radiator, near the oil filter.



Replacing the electric water pump only requires removing the Splash shield, two hose clamps, two 10mm bolts, and one electrical connector.

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