Battery fan gets no power

Did you unplug the fan connector and notice any browning or corrosion on the contacts of that big white plug If so you may need to do something there and that fan just shouldn't be running all the time I mean you're talking about the cars warmed up you've been driving in the fan should be on and it's not and you can touch the battery pack and it's warm etc? Then maybe the fan should be on I know if your battery starts messing up that fan will come on and won't shut off so if in fact the fan works with the solid 12 volt power supply like connected directly to a battery if you know the correct terminals to connect and the fan works then the car should work the fan when it needs to unless there's a break in the circuit coming from the fuse box to the trunk plug. You could always connect a vote meter to that and run the test leads in the window and set it on the dash drive the car and see if the fan wire ever gets power from up front then if it doesn't probably a sensor or something would be suspect or the east power ECU that controls the fan All of these areas are known for corrosion in the plugs one of the first things you want to be looking at and then since you're going to have part of the cover off you might have of the battery you might as well lift it up and look at the corrosion on your bus bars and nuts while you're looking at things.

 

What is getting hot You got some temperature readings from Dr Prius or tech or something? My fan rarely comes on It's got to be summer no air conditioning on Windows half mast something and usually I'm never riding like that I usually have the air condition on low not set at a temperature on LO ice cold whatever the fan is on it's on and that cold air is going straight back to the battery and wherever it wants to go rarely do I pull in the driveway and hear my battery fan running It's extremely rare and I will hear it because it's so rare and I pull in and shut everything down just like an airplane pilot air conditioning is turned off stereo is turned off fans are not blowing nothing is happening when does they're up or cracked or however they're going to be left and then and only then is the car powered down and I almost never hear a fan running when I'm ready to push that button to go completely dead and if that fan is running it's usually on upper mid to high and you can hear it clear as day and like I say I usually don't and we drive the car it doesn't drive us.

 

If OBD is showing the fan activated and the fan isn't running, that would be enough to convince me there's something to investigate about the fan circuit.

 

You need a different (more capable) scantool. P3000 is the hybrid control ecu saying, "the HV battery ecu told me it has a problem, you should go over there and check it out".

That said, you should get a copy of the service manual and wiring diagram. There's a fuse and relay that supply power to the fan. The relay doesn't close until the battery ecu turns it on (& that only happens when the dcu commands the fan on).

Also, it is very common on a Gen2 Prius for the body seam around the tailgate hatch to leak. Water gets into a white inline connector near (for) the fan and corrodes it.

Posted via the PriusChat mobile app.

 

There is a black plastic duct that mounts between the fan outlet and the upper portion of the HV battery. There should be a small relay mounted on the upper passenger side of this duct. That relay is for the HV battery fan. Perhaps it has failed or is not plugged in? There is also a controller, identical to what controls the HVAC fan, located in the exhaust duct. These are normally very reliable components, so I've never really dug into how they function with each other. It may be worth checking.

 

What you went on to describe is NOT the HVAC fan.

But it looks like you are really talking about the battery fan.......and that is what
everybody has zeroed in on.

 

You could wire that battery fan to str8 12 V and just have it run all the way home . If the inverters charging the 12 volt that should not cause you any strife to get the car home I don't know the answer to all your questions about the IN1 business and what have you I would think all that the voltage has to go back there through the relay and then there's a sensor inside one of the ducts etc All those things have to be in given positions or activated for the fan to come on under certain conditions high heat obviously but I mean the settings of those individual little controls.

 

As the OP has already seen on a scan tool that the ECU reports that it is driving the fan at highest speed, we can kind of cross off the list things like temperature sensors that figure in to how the ECU decides to do that. So the OP can focus on just the things that stand between the ECU already deciding to do it, and it happening.

 

Yep and apparently no power on fan plug .usually they're in a state of corrosion alot.

 

The diagram shows that IN1 is "upstream" of the control relay- there should be power at that gray wire (pin11) at all times.

I would try to jumper 12V (ideally with a fused wire) to that point on IN1 - see if the fan will work.

Posted via the PriusChat mobile app.

 

I had the same problem a few years ago: fan not running, traction battery overheating, then red triangle when a module failed.

Troubleshooting revealed that fan was perfectly fine, but relay was not actuating. Traced problem to corroded contacts in the Molex connector that mounts to the fan bracket. The corroded wires were the ones feeding the fan relay. After bypassing the corroded pins with a new, waterproof connector (and rebuilding the battery pack), I haven't had a problem since. Hope this helps!

-Harry

 

Excellent work That looks like a Marine 12v connector.. Do you have a link to the supplier?

 

I remember this original post I think Harry Glad you showed up with the pictures because I don't have them and can't easily post them I remember when you did this repair Good show

 

For a seaside car that car looks damn clean buddy I don't even know what year it is but it looks like brand new usually behind those panels where that corrosion is on that molex plug You can see the water drops possibly some rust forming on the metal that's beside the spare tire well etc etc etc your car looks like it's never been touched.

 

I should have mentioned, this was our blue 2005 Prius, not our green 2014 Prius v. The '05 is still going strong with several thousand miles on the rebuilt traction battery, but I still have a few good, spare modules standing by, just in case.

-Harry

 

That connector is very easy to just eliminate. On every one of my Gen2's, plus most that I've done battery jobs on, I've cut that connector out, spiced the wires together and insulated with heat shrink. Permanent repair for wires that never need to be unplugged anyway. The only time I don't do that as a complimentary service is if the connector and wires are in perfect condition. Any corrosion at all and it gets 'fixed'.

 

I bought a pack of two-wire connectors on Amazon. I looked for ones that were waterproof, since my '05 has the typical roof leak (the 12V battery lived in a swimming pool until I opened a drain hole in the bottom of the compartment. In this case, though, the corroded pins didn't look like they suffered from water damage. It appeared to me the wiring harness may have simply been spec'ed with wires too thin for the fan relay's current load. I didn't try to measure it, but the new connectors came with beefier pins and 18AWG wires.

As TMR-JWAP notes, it's easy to replace the entire connector. Mine only had one other pair of wires, so I could have replaced the whole thing with the 4-wire version of the same connector if I had thought about it.

-Harry