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View Full Version : FEH/MMH diagnosis?


hobbit
05-30-2008, 12:05 AM
I had a chance to look at an acquaintance's Escape hybrid a couple
of days ago, who was complaining that he'd occasionally get some
sort of high temp warning [unclear if for the engine or hybrid
system], and eventually the screen would say "stop now" and the
thing would disable itself. A key-off-on restart seeed to reset
it so he could keep driving, but it's not what you call a
confidence-building situation. His A/C works fine [relevant
because of its role in battery cooling], all the fluids are
okay, etc. I will also note that someone is recently asking
about similar issues over in Priuschat (http://priuschat.com/forums/f/48125-problem.html).
.
Is there a TSB on this sort of thing, perhaps? I don't really
keep track of the deeper FEH mysteries, so I thought I'd ping
the collective knowledge here.
.
This guy is also seeing the "service emissions sys" message on the
little LCD every time he starts up. What might that mean? He
seems to think that everyone who owns one of these has that
message all the time and it doesn't mean anything serious. The
car has 90-something K on it, I think, so I'd believe it if
someone said it was a built-in arbitrary mileage timer that
assumes an O2 sensor must need replacement by then. My old
Trooper had something similar in the speedo, that lit whether
the sensor was bad or not.
.
When I drove it, I was of course comparing what I observed with
the Prius UI. The pedal response seemed heavy and delayed by
comparison, almost as though Ford was trying to simulate
everything that's wrong with how stock automatic transmissions
feel. EV mode seemed fairly hard to attain, although I hadn't
read up on FS and LGA recently so I couldn't remember what any
of the tricks were. Other than that it seemed very smooth,
positively cushy at times; I'm sure the tires weren't up to
where they should have been, but the owner isn't really a MPG
fiend and tends to drive the vehicle pretty hard.
.
Anyways, any advice on what to check [preferably for cheap/free]
appreciated. I'll pass it on.
.
_H*

CarlD
05-30-2008, 01:40 AM
A few things...

Electric water and/or motor electronics cooling pumps. Known to go bad on occasion.
Can program some xgauges to look at motor electronics coolant temp, motor and generator coil temps, and motor/generator inverter temps.

TSB for HV battery harness work. I have not gotten a "Stop Safely Now" message since the work was done.

You can monitor the downstream O2 sensor to see if it is switching, which it obviously shouldn't be. I have 80k+ and have never seen a "service emissions sys" that I can recall.

Dan
05-30-2008, 08:32 AM
Where most prius drivers install thier EV button, the MMH has three buttons {info; setup; reset}, all to the left of the steering wheel. With the car on, doors closed, safety break off you can check the user diags. Just click "Setup" and you should see a message "Press Reset for Diagnostics" or something like that. Now hit "Reset" and you should see the LCD on the speedo go through and give go a systems go/nogo. One thing you want to look for is "Electric System OK".

Basically if your battery AC is going out or your having some pack failure, I'd expect it to say Electric System Failed or something like that. When the diag is done you can just keep hitting the "Info" button to scroll through all the messages. The last one before the "blank" screen should be the Electric System with a status of "OK" or something else "not OK".

This is real remedial stuff, but it might point you in the right direction.

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