P0A7C criteria PCM parameter / wrench light?

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samster2.0
Posts: 3
Joined: Sat Oct 21, 2017 2:20 am
Vehicle: 2012 Fusion Hybrid; 2011 F150; 2007 F150

P0A7C criteria PCM parameter / wrench light?

Post by samster2.0 » Wed Oct 25, 2017 2:13 pm

I have a 2012 Fusion Hybrid. I live in TX and do a lot of high speed interstate driving, and so I get the P0A7C "Motor Electronics Over Temp" code and wrench light almost every day when driving at 75-80mph and when outside air temps are in the 80's or above (which is practically every month except Nov-Feb). No driveability concerns, just irritated that the light keeps coming on.

I used Forscan to scan the MECS_V PID to determine if the temperate of the MECS coolant was in fact going really high... turns out, its in the normal range even while the wrench light comes on and the code is set.
Supposedly the MECS coolant temp is not supposed to exceed 150F in "normal driving". I never even get close to that. In fact, the MECS temp values are higher when I'm NOT going at high speed, but they are higher when I'm going slower or stopped. I've already had the dealer replace the MECS pump for the newer style, and they don't know what's causing the wrench light. They said if I take it back in again, the only thing they can do is replace the entire engine/transaxle - at my cost, of course.

I've read that there are TSBs for earlier model fusions that address this issue.
Does anyone know what values they affect?
As far as the MECS pump goes, its either "on" or "off", and from documentation, its "on" anytime the key is on. Mine does not have any faults, and is always on like it should be.

I'm thinking there's some sort of a "temperature limit trigger" parameter in the PCM that needs to be adjusted higher, but not sure which - or even where to go to try and find out which parameter.

Any thoughts?
Thanks!

ThatOneDude
Posts: 93
Joined: Fri Jul 07, 2017 12:46 pm
Vehicle: 2007 Ford F-150 SuperCab 5.4L 3V 4WD

Re: P0A7C criteria PCM parameter / wrench light?

Post by ThatOneDude » Wed Oct 25, 2017 11:26 pm

Sounds like the motor electronics module itself is over temp, and the MECS_V PID is reading the temp at the MECS pump. I would take that as an indication that the MECS pump is inoperable if they are separate units. Is there a separate PID for the temperature inside the motor electronics module?
1996 Ford F-150 300cid I-6 (Scrapped)
1991 Lincoln Town Car (Scrapped)
1996 Lincoln Town Car (For Sale)
2003 Ford Crown Victoria Police Interceptor (Sale in progress)
2007 Ford F-150 SuperCab 5.4L 3V 4WD
2011 Ford Crown Victoria Police Interceptor

samster2.0
Posts: 3
Joined: Sat Oct 21, 2017 2:20 am
Vehicle: 2012 Fusion Hybrid; 2011 F150; 2007 F150

Re: P0A7C criteria PCM parameter / wrench light?

Post by samster2.0 » Thu Oct 26, 2017 12:23 am

I'll have to check the service information CD I have, but I believe that the MECS temp sensor is the only temp sensor in the MECS cooling circuit. It's already located directly in/on the electric motor, measuring the temp of the coolant at that point.

I'm thinking that the criteria is something to do with the relationship of the MECS_V temp sensor voltage related to the VREF voltage value, and maybe the problem is really with VREF?

Also of note, the coolant degas reservoir for the MECS doesn't even have a pressurized cap. When I stop the vehicle after driving it, its cool enough for me to open it and stick my finger in the coolant.

Poletoff
Posts: 4
Joined: Sun Dec 10, 2017 6:29 am
Vehicle: Ford Escape Hybrid 2,5 2010

Re: P0A7C criteria PCM parameter / wrench light?

Post by Poletoff » Tue Aug 07, 2018 7:04 am

Same trouble wit Ford Escape Hybrid 2010MY.
Ran on the highway. The temperature in the street is 91-92F. Inside the machine, the temperature is 73-74F. The speed is 75 miles per hour. There was a wrench and error P0A7S. After that several times I saw this error, but only on the road and only in hot weather. Ford has a TSB, but only for Ford Fusion, Lincoln MKZ and Mercury Milan. I do not know if this can help.
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