P0A7C criteria PCM parameter / wrench light?

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wr400f250
Posts: 23
Joined: Sat Oct 05, 2019 1:01 am
Vehicle: 2010 Fusion Hybrid, 2009 Escape Hybrid, 2003 Explorer 4.6

Re: P0A7C criteria PCM parameter / wrench light?

Post by wr400f250 »

The major difference is that city driving is far less demanding of the powertrain. In order to maintain engine RPM at highway speed, MG1 (the motor that starts the engine) has to spin continuously at a ridiculous speed, constantly fluctuating based on throttle input. The reason our cars are limited to 108mph is because that's the redline of MG1. In order to maintain that RPM, MG1 has to shed that electricity somewhere. Some goes to MG2 to assist the wheels, some goes to the battery as needed, and the rest goes to the A/C compressor and accessories. On the highway, this is all continuous, without rest.

During city driving, MG1 is only used occasionally, and gets regular breaks. Based on the data from my trip to AZ, the cooling system is plenty overkill for both scenarios. The temps that got me concerned were taken mainly from MG1, which is bathed in transmission fluid rather than coolant. I'm pretty sure this is the main reason Ford added a small transmission cooler to the next gen Fusion hybrid.

Normally it would be easy to add one, but our cars don't have any sort of pump built into the transmission.
ahernandez15
Posts: 4
Joined: Tue Jan 05, 2021 1:46 am
Vehicle: ford fusion hybrid 2010

Re: P0A7C criteria PCM parameter / wrench light?

Post by ahernandez15 »

Just took the car out for a spin. The motor electronic coolant temp stayed at 120 °F all trip. When the wrench triggered the only number I saw spike up was the generator inverter phase temp. Went from 178 to 207°F then in a second down to 176°F and the light came on at exactly 207°F mark. Trans temp was pretty high all trip at 180 in 108 degree weather. Idk what to make of this.


And guess what just saw the service manual and when it goes over 176°F it will trigger the DTC. The thing is it doesn't trigger (DTC P0A94:4B ( DC/DC Performance: Over Temperature) — Sets when the MECS temperature exceeds 80°C (176°F) and/or the DC/DC is limiting current output to 100 amps) or DTC P0AF7:00 14 (Volt Power Module Internal Temperature Too High: No Sub Type Information) — Sets when the DC/DC senses high internal temperature. It triggers P0A7C. Which is crazy. But I feel this is going somewhere. Based on the data it only went to 207 for 2 seconds so maybe an air pocket??
ahernandez15
Posts: 4
Joined: Tue Jan 05, 2021 1:46 am
Vehicle: ford fusion hybrid 2010

Re: P0A7C criteria PCM parameter / wrench light?

Post by ahernandez15 »

Ok guys. Did the test today Again. While monitoring numbers cars generator inverter phase temp goes up once you hit 65+ mph. I took it all the way home slowing down when the temp was going up. And it would drop. To prove my theory I gave it hard gas and took it too 210°F on the inverter and wrench light came on with code. Just like yesterday it dropped once I coasted it. So the temp on the inverter is the issue. Motor v electronics coolant was at 125°F btw
wr400f250
Posts: 23
Joined: Sat Oct 05, 2019 1:01 am
Vehicle: 2010 Fusion Hybrid, 2009 Escape Hybrid, 2003 Explorer 4.6

Re: P0A7C criteria PCM parameter / wrench light?

Post by wr400f250 »

That mirrors what my Fusion did. Definitely seems like an air pocket in the coolant is the main culprit.

Pretty sure I included it in one of my earlier essays, but there's another bleed screw just behind the inverter in front of the brake booster. Not sure if it'll help in your situation, but maybe good to experiment. Be careful because it's really easy to drop that bolt.

I think I'll steal the Fusion from my sister this weekend and tinker with it. Need to fix a headlight connector anyway.
Continental_man
Posts: 7
Joined: Sat Jun 26, 2021 10:18 pm
Vehicle: 2010 Ford Fusion Hybrid Atkinson engine

Re: P0A7C criteria PCM parameter / wrench light?

Post by Continental_man »

I’m having the same issue with my wife’s 2010 Fusion Hybrid

I live in AZ right now temp outside is 105 and after driving for about 30-40 mins at highway speed I get pull over when safely or it just cuts out. I scan the codes and get the motor electronics over temp code.

I drove it today to duplicate the problem and I can see it getting overheated. Dealer had it and said everything is fine and could not fix it. Supposedly they reflashed ECM for the $175 diagnostic fee but it never solved any problem. I even gave them the codes and they said there was no codes in the computer.

Today I let the car sit in the driveway while I revved the engine to get it warm and I see it getting hot. I sprayed the mecs small radiator and temp drops off dramatically. It won’t let me post pictures because it says file is too large.

I am hoping someone has a fix for this because FORD was useless.
wr400f250
Posts: 23
Joined: Sat Oct 05, 2019 1:01 am
Vehicle: 2010 Fusion Hybrid, 2009 Escape Hybrid, 2003 Explorer 4.6

Re: P0A7C criteria PCM parameter / wrench light?

Post by wr400f250 »

What was your MECS temperature showing? Both on the highway and revving in park.

It should be nearly impossible to overheat the MECS system in park. There simply isn't enough work the powertrain can do in park that would overwhelm the cooling system unless you have a clog, huge air bubble or a bad pump.
Continental_man
Posts: 7
Joined: Sat Jun 26, 2021 10:18 pm
Vehicle: 2010 Ford Fusion Hybrid Atkinson engine

Re: P0A7C criteria PCM parameter / wrench light?

Post by Continental_man »

On highway temps
Generator Inverter Phase 232F
Motor coil temp 238F
Motor Electronics Coolant 144 F
Motor Inverter Phase 155F
Transmission Fluid Temp. 221F

The trans temp was red on my scanner and while I was driving aggressively on the highway trying to get it to give me the wrench light and cut out I finally chickened out and drove home. I don’t want to get stranded for the third time. I have had to tow this car now twice.

I didn’t take a pic of the temps on the driveway but I was monitoring them while I was spraying water on the mecs radiator and I could get as much as a 30 degree swing in temp difference.

I placed a digital thermometer on the gas bottle and I could see a 30 degree difference between the scanner temp and the gas bottle temp. Scanner would show 110 degrees for coolant temp and the thermometer would show 144F.

I put a stethoscope on the mecs pump and I hear it running but my thought is since it’s able to cool down while spraying water rather well, I’m thinking it has something to do with volume delivery. Maybe the pump is not moving enough coolant to dissipate the heat fast enough.

Tomorrow I’m taking the system apart and bleeding and backflushing the system. I’m hoping for a clogged radiator or weak pump.
Will keep you posted
Continental_man
Posts: 7
Joined: Sat Jun 26, 2021 10:18 pm
Vehicle: 2010 Ford Fusion Hybrid Atkinson engine

Re: P0A7C criteria PCM parameter / wrench light?

Post by Continental_man »

I finally figured out how to resize the image. This is the temp while I was driving on the highway
9E7FDE5F-37A1-48BD-9696-952D8B35959D.jpeg
9E7FDE5F-37A1-48BD-9696-952D8B35959D.jpeg (58.28 KiB) Viewed 220 times
Continental_man
Posts: 7
Joined: Sat Jun 26, 2021 10:18 pm
Vehicle: 2010 Ford Fusion Hybrid Atkinson engine

Re: P0A7C criteria PCM parameter / wrench light?

Post by Continental_man »

Here is one set of codes I get
Attachments
7D8C8EE2-9B40-4CCC-A4A5-93DFE8022B4A.jpeg
7D8C8EE2-9B40-4CCC-A4A5-93DFE8022B4A.jpeg (61.42 KiB) Viewed 219 times
Continental_man
Posts: 7
Joined: Sat Jun 26, 2021 10:18 pm
Vehicle: 2010 Ford Fusion Hybrid Atkinson engine

Re: P0A7C criteria PCM parameter / wrench light?

Post by Continental_man »

Update…. I ordered a new pump from Vatozone and installed it. Bled the system and now all temperatures are closely with each other + or - 10degrees.

Before the motor electronics coolant temp would stay stagnant and all others would be wildly going up and down.

Interesting enough after I took the original MECS pump out and after I fed it 12VDC it would not run at all. Completely dead! On Sunday I had checked it with a stethoscope and was humming and vibrating and now is dead.

Now after bleeding the system and fighting with the pain in the ass bleeder screw on top of the inverter, took the car out for a spin.

Temperatures looked promising because all were staying pretty well in line with each other and before they were off quite a bit.

Drove the same way I did on Sunday with a 93 degree outside temp and gunned it to get on I-10 and immediately cut out and went to pull over when safe.

Pulled over shut the car off and turned it back on and while looking at the scanner all my temperatures were below 190 except for the generator inverter phase. That one was at 260.

Started the car and drove off again, once I hit 260 degrees it cut out again. The generator inverter phase temp code is now showing on the TCM.

My theory at this point is I have an air pocket in the system. Why all my other temps are 160, 170, 190 and only one is 260. Even the electronics coolant temp was around 150-160.

Something that I also noted was that after I replaced the pump and after bleeding the system, I could actually hear and see coolant moving in the degas bottle. Something that I have never seen this car do ever since owning it.

Even though the car cut out 3 times on me on a very short drive. I’m feeling confident that I have an air pocket. All my other temps are good just the inverter generator phase is the one I’m having issues.

I got to order a vacuum bleeder from Amazon so I will have to wait until that shows up then I will keep you posted.
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