HV battery cooling fan issues

You can check the HV battery fan and force it to run but it will take an OBDII device such as ScanGauge, Torque app for Droid phones, Engine Link for iPhones with Prius specific PID's.

 

best thing to do is open it up for exam and cleaning if necessary. it's not that big a job and is described here with pics. all the best!

 

What bisco said, this should get you started.

Battery Fan Cleaning | PriusChat Also study the pdf file that is found on that page. Has diagnostics you can run if you have the correct code reader, plus instructions on the tear down and torque ratings.

You have to pull the side panels to get to the fan. Probably stopped up with all sorts of fuzz and stuff. Having animals in car makes it dirty fast. Common problem with the old Prius.

FWIW, if you ask the dealer about it they will recommend replacing the fan unit rather than cleaning it. As long as the fan is working and the squirrel cage is clean there should not be any problems with the fan itself.

Hopefully cleaning up the fan will solve the problem of the code you are getting.

Best of luck to you!

 

It won't hurt to replace the 12V battery but that is not going to be the issue here.

P0A85 means that hybrid battery cooling fan voltage is actually higher than expected. This is quite unusual and would imply that the fan is not spinning.

Here are a few things you can check:
1) Find the 10A BATT FAN fuse which is located in the main relay/fuse box next to the inverter. Remove the fuse and test continuity using an ohmmeter. Do not rely on visual inspection.
2) Find the battery blower relay which is a few inches away from the battery cooling fan. Use an ohmmeter to determine the relay coil terminals. The other set of terminals are the switched terminals. Apply 12VDC to the relay coil and measure resistance across the switched terminals. Replace the relay if resistance is more than 0.5 ohm (after accounting for the resistance in the ohmmeter leads.)
3) Find the battery cooling fan. Apply 12VDC to the fan and confirm that it rotates.
4) Look for an issue with the electrical wiring harness.
5) If you don't find an issue with the first 4 steps above, the issue may be with the battery blower controller or the traction battery ECU. The ECU provides requested fan speed to the blower controller via a pulse width modulated signal.

If you want more info, subscribe to techinfo.toyota.com for repair manual and electrical wiring diagram info.

 

The HV battery charge swings does not bode well for the state of the battery. This is a typical symptom of failure possibly bough on by the cooling fan not working. I hope when you get the fan sorted this problem goes away, but I doubt it will.
The Mini VCI off Ebay or Amazon "less than $30 plus your laptop will enable you to read and remove any DTC codes. It will also give you full diagnostics of your HV battery, and just about everything else on the car as well as service tasks like bleeding or flushing brakes.
See page one of two print out for HV battery below.

John (Britprius)

 

Hi lengele, what type of battery did you replace it with. Was it new, refurbished or plain salvaged? Unfortunately it seems like that battery is failing again.

And what were your findings wrt the fan. Was it badly blocked or just a minor dust build up.

Also, many people don't realize how often the fan runs, though at low speed where you normally can't hear it. If you drive for more than about 20 minutes or so on a warm day then you'll probably be able to hear it running softly. Stop the car at the end of a trip but don't shut down, leave it in ready mode and shift to "P". Then get out and walk around to the rear door and place your ear right next to the vent. You should be able to hear it running quietly. This is a good way to test.

 

DTC P0A85 means that the battery blower voltage is greater than expected. If the fan is operating and the blower relay was replaced, perhaps the blower motor controller (located in the vent duct) has a problem. Or, the traction battery ECU has a problem.

 

Hi lengele, have you been able to confirm that the blower is working? If you drive for a while in warm weather then you should be able to hear it running quietly if you place your ear right next to the vent.

 

Hi all I have the same problem and the fan who should be cooling down battery is stopping working after few minutes and the error shows up. The blower motor controller is hot after few minutes is it should be like that?

 

When fan working to cool down battery the controller unit that is inside the black pipe with coil is heating and that turns off and again error on dashboard.

 

i don't think so, but you should get a mini vci and see what it's reporting. the error is telling you that something is wrong.

 

Yes I done this error code is POA85

 

looking at patricks post #10 above, you still need to narrow it down to the relay, blower motor controller, or traction battery ecu.

 

Hi I'm a newbie here, but I already went through on so many posts and I already got lots of great idea and solution for different issue. However I've got the same fault which is described above and I already checked the relay, wireloom, etc, all in good shape and operational. I narrowed to the ECU or Controller (B10). Any suggestion how can I pick the right one? I was thinking to replace the controller. Is it only available from the dealership or from other sources as well?
I would appreciate some help even this threa is quite old I hope someone whatching it...

 

welcome!
no, i don't know how to diagnose the specific problem. you might need tech stream and the service manual troubleshooting tree. but someone else more knowledgeable may be able to help.

all the best!

 

Thanks I ordered one from Ebay, but takes a bit of time to get here. At the mean time we managed to make it work, but nothing to pointing as an issue. Possibly the connector of the controller had some corrosion and as we disconnected a couple of times it may cleaned (was no visible sign of corrosion at all) itself. So it is ok for now but I'm still concerned. I'll report back if the fault will return.

 

The workup for p0a84 / p0a85, in case someone needs it:

http://ww2.justanswer.com/uploads/skyvisions/2008-06-21_094224_05_prius2.pdf