The main way to lose Freeze Frame data is to clear codes or disconnect 12V battery.


It should NOT be able to "reset itself". That could be a no-no in some states.

 

Ok, so these codes have been popping up about once a week or so. Then they reset themselves. My OBD never read it logged it as a full fault, just a pending fault. Anyway, I drove it 2 hours to a battery specialist. Full testing showed the batteries were all good. He said he saw some other codes about they cooling fan and bad communication to the central computer. After a couple hours, he told me the torque sending unit failed. Wha?? Haven't ever read anything like that here. Anyone know what that's all about?

 

I think that's supposed to be changed out when the replace your blinker fluid.

 

Well, $225 later, no difference but a clean, slightly cooler battery pack. Maybe my HCU and TCU need calibration? 5 minutes into driving it, surge from a stop. Still only getting 18 mpg.

My blinker fluid was orange. Thanks for your help.

 

No such thing in a 2-Mode as a "Torque Sending Unit". It calculates torque based mainly on the current it sends to the motors.

 

And that P061B only sets when there significant voltage differences between blocks of cells.

 

He did a full diagnosis of each cell and didn't notice any anomoles.

 

There are 40 ( 6-cell ) modules. They are wired in 2s as "blocks". There are 20 volt-meters in the pack.


When the voltage differs from maximum to minimum between those 20 by enough ~ 1.5V a code sets.


If the Check Engine light and Service Hybrid message comes on, they do not re-set. Something external can re-set, or removing 12V.


So unless he took that pack apart and tested all 40 modules, I'm not sure what he did.

 

He removed the battery pack from the vehicle, removed all the copper jumpers, cleaned all the terminals, and said he voltage checked and load checked each cell.

That's what he charged me for, anyway. Oh, and he cleaned some dog hair out of the cooling fan.

Also checked the 12v which he said was good, but was dated 2012. It's an AC Delco 770 CCA (Not common to buy).

 

"Full diagnosis" really has no meaning. It usually means, "I looked at the codes and pulled up the data."


A full diagnosis involves a thorough evaluation of the battery block voltages and their response to charge and discharge currents of varying levels. Nobody does this as a matter of course, and those that do, often don't realize how critical the block voltage deviation is.


When properly done, one can actually measure the available capacity of the pack and estimate its state of health.



Given what I know about Toyota prismatic modules in hybrid vehicles, 1.5V deviation means it failed badly. 1.2V means a cell has outright failed. The reality is that all 20 block voltages should be within about 0.2V or less of each other. Under heavier load, 0.3V is generally acceptable. Under max assist (150A) and regen (90A), it should generally be under 0.5-0.6V.


If you get a block voltage error code, and your voltages are over 0.3V resting and 0.6V under moderate loads (15A running the A/C and all 12V accessories when engine is stopped), your pack is done.


Other things to watch for are block swings. If block X is the lowest on discharge AND the highest on charge, you have a failed cell in that block.


Lastly, too few people know this, but a SINGLE cell failure in a NiMH pack renders the pack unusable. Period. It is a limitation of the technology. There is no way to engineer or design a way around this. One can say that it's silly that it's that way, or it shouldn't be that way, but that's just ignorance.


If you use a NiMH pack, that's the consequence. Dead cell = dead pack.