Hey all,

I need some help diagnosing my problem... It used to be as soon as I turned the key to run, it seemed that a fan in the back would start. Maybe it was a pump? Well this is my wife's car and I don't drive it much but now when I drove it, I no longer get that at start up and it has to be driven a LONG time before going into battery mode.

I've read about the MECS pump, blend door actuator, cooling fans... I don't know what SHOULD be happening and where to begin diagnosis... Help a guy out!

Thanks!

 

BTW 51,000 miles and no check engine lights etc have ever come on, but it does not appear to be running correctly...

 

It doesn't sounds like a overheating problem like those things would cause. It sounds like a warm-up problem and a stuck open thermostat like we are presently posting about. Check out that thread.

Gary

 

OK, I could buy that except for the fact that I used to hear a motor running when I turned the ignition to run... even if the car was not started, this fan, or pump, or some motor in the back would start running for a few seconds... Now it is silent. I always thought it was a cooling fan or something to evacuate the fumes from the HV battery back there...

As far as going into EV mode, it takes a long time in the city if at all but driving it to work today it finally did after getting off the highway and a 20 minute drive. That would go along with your t-stat analysis... But what about the motor at start up??? Does yours make that noise at start up? Turning the key to run without actually starting?

 

The only noise from the rear is the internal battery fans for cooling only. There will be a DTC code for the bad fans, so take it to your dealer for confirmation. It has been noticed that once the battery is heated without the fans running, no EV will happen after that. The Cabin A/C must be working and blowing cold air for the Aux battery A/C to be working. The battery A/C will cause overheating also if not working. You should hear the MECP motor running under the radiator with the Key On without the engine started. Check these conditions and let us know.

Gary

 

Cabin AC is cold and strong, NOTHING runs when the key is on but not started... maybe the battery fans are bad and that is causing the problem? Why would it go into EV mode after a 20 minute trip on the highway though? I would think if the battery fans were bad I'd get a check engine light?

And will the dealer check for codes without a charge? I know I don't want them to fix it at their prices???

 

It's relatively easy to check if the battery fans are running. See attached picture. Take out the mat in the back. On the left side is a black plastic cover held in with some screws/bolts. Remove them and you can remove the black plastic cover and ducting. You'll then see the inlet and outlets on the battery, covered by some screening. Turn the key to on (or start the vehicle) and you should feel the air being sucked in the forward duct screen and blowing out the rear duct screen.

 

This may or may not help understand the hybrid battery pack:

 

ok, here's where I'm at... I just got the car back, (numerous family drivers), I started the car to let it run for 10 minutes as Gary suggested, the top (smaller) hose to the t-stat got warm the large (bottom) hose stayed cold, then at about 7-9 minutes? didn't look exactly, it went into electric. When it did, I could hear a whineing like air being let out of a balloon on the lower driver side and tracing it out, that appears to be a small pump, the MECS Pump? with two hoses attached and the hoses felt like water was being pumped through them. Sounds like it may be ready to be replaced.

Now the questions:
There is another slightly larger pump on the passenger side under there also with two hoses, what is that?

Also through all of this, NEITHER radiator fan came on and the large hose to the t-stat never got warm... when should these fans come on??

I will check on the back battery fans, but one thing about back there, I did take off the filter cover before with it running and that door below the filter was closed and never opened up? Should that open immediately? Is that the blend door problem?

Thanks everyone for the help!! I hope to avoid the Stealership!

 

The small pump is the EV cabin heater pump. It comes on only in EV. The larger pump near it is the MECP that should be running with the key ON.

The radiator fans should come ON only when needed to cool the coolant in the radiator when hot.

The battery filter door is closed most of the time to bring up temperature in a cold battery. It's not a sign of a blend door problem, only a trouble light will come ON for that.

Gary