Well I just picked up a new to me 2009 Highlander Hybrid with around 200K kms (120k miles) on it. Car was just beautiful and I certainly saved a TON over what similar year models were going for up here in Canada. I knew going into it that I would need to fix a few things to make it perfect and of course a high mile hybrid didn't disappoint.

Upon firing up the vehicle for the first time after taking delivery it immediately showed the traction control, "check brake system" and "check hybrid system" lights on the dash. Traction control issue was due to insufficient air pressure in the tires so that was easy and light is now off. The other 2 were more preplexing so I hooked up my OBD reader and found the P3011 code stored (nothing else). First I cleared the codes and extinguished all the dash lights. Then I immediately started charging the 12V engine battery to make sure that wasn't the issue so for now the car is too new to know but I thought I would document this in case others are in the same situation later and are looking for a solution as I find the cause on mine.

I haven't seen any good writeups on rebuilding a Highlander Hybrid battery pack yet so if I end up doing that with mine I will add some photos to the thread as well. I've got quite a bit of electronics experience so if it comes down to that I'm certainly up for the challenge.

If anyone has any hints, helpful links or info on the cause of this code, I'm all ears.

 

Just a follow up that it looks like charging the 12V engine battery every night using a good quality smart charger (I used a CTEK 3300 which can handle AGM batteries) did the trick. The code hasn't come back and the hybrid system appears to be working as expected. It seems that since your 12V engine battery is also charged by the hybrid system, if the engine battery voltage drops too low it will put a load on the battery blocks in the hybrid system causing codes like the P3011 I saw above. This was probably due to the vehicle sitting on the dealer's lot for too long without being used/driven. At this point it appears to be fixed anyway.

If someone later had this issue and it kept coming back, the first thing I would do is to charge the 12V battery and have it AVR load tested at Toyota (replace if life is below 60%).

 

Update: I had this happen again while on a ski trip and my daughter left the interior lights on overnight. I didn't have my OBD reader with me to clear the codes so I just drove it for an hour (to charge the hybrid battery) then used a 10mm wrench to undo the negative battery terminal, waited 5 minutes and then reattached it again and the codes were gone (ie no more flashing displays). I also wished I had brought my CTEK charger and an extension cord on the trip so I suggest if you are going on a long trip it's wise to bring them with you just in case (ie I could have charged the battery at the hotel instead of having to drive around to charge it). Hope this helps if someone else runs into the same problem.

 

The code has started to come back more often and charging the 12V has not been helping so I suspect this may require me to do some testing on the blocks of the main traction battery. I posted this in another thread but I thought it would be helpful here as well. Highlanders at least up until 2011 (not sure about 2012-2013) are still using the same 9.6V modules they did from when they first came out in 2006. Often it is a single bad cell that can bring down a block (all 30 modules in the Highlander battery are paired into 15 blocks and each module with 8 cells at 1.2V......that's how you get the total voltage of the battery 30 modules x 8 cells each x 1.2V = 288V). Unfortunately they don't use the same battery as the Prius or the Camry (both use the 6 celled 7.2V battery, again each cell is still 1.2V) or there would be a lot more options for us to be rebuilding Highlander Hybrid battery packs.

My next step will be to have Toyota load test the 12V battery and then hook it up to the scanner to watch the voltage on each block of modules. I suspect Block 1 has issue but I'll be able to see it in action by looking at all of them together (the ECM tries to balance the voltages across all the blocks so if one is regularly low it will begin to affect the others as well).

You can see what it looks like when a block is bad here (last page):
http://www.autoshop101.com/forms/Hybrid15.pdf

 

Well the saga continues and the P3011 has become more frequent now. I just replaced the 12V battery to see if that improves the issue but if not I may be tearing into the traction battery soon to hopefully get this resolved permanently. It is very clear that these vehicles are very sensitive to lights being left on, doors/hatch adjar, etc. The battery on the 2006-2009 are regular lead acid (group 51R) since they are located under the hood while the 2010-current are located in the trunk and must use an AGM battery instead since it would outgas into the cabin otherwise.

 

I haven't torn into the battery yet but interestingly I think I may have found the connection between why on hot/humid days the code popped up alot more often. The AC on these hybrids is electrically driven (not belt driven like most vehicles) and therefore if you turn on the AC right away the high current draw always seems to pop the P3011 code. If you allow 2-3 minutes of driving before you turn on the AC it will allow the batteries to stabilize again and no code for that outing. I would stress this is more of a workaround than a fix, but I just wanted to relay this in case others might be facing a similar situation as it does seem to prevent the code from triggering at least to some extent.

Also if you need a cheap code reader to clear codes when they come up, then AGT (Advanced German Technology) brand OBD2 Reader (costs around $30) makes a very inexpensive tool you can keep in the car and use as needed.

 

In case someone wants to see what I have been doing to solve this issue , itīs all in this thread on Priuschat (esp read pages 11-13 where I solved it).

http://priuschat.com/threads/gen-ii-...cement.125588/

I also suggest reading this thread as well since anyone working on a Toyota hybrid should have one of these too.

http://priuschat.com/threads/xp-home...ni-vci.137564/

 

Problem is now solved, nice to have it working the way it should again!

Solution is in the thread mentioned above.

 

Just wanted to report back vehicle drives so well now my wife is considering buying another one now.......no issues whatsoever since.

 

i've considered the 06-07 body styles over the 08+ body styles due to their nicer pricing arrangements and performance (lighter body)

although the 08 are much nicer but pricier as well