"Check Hybrid System" light comes on after driving through heavy rain

Welcome to Prius Chat .

Have you looked in the back spare tire area for water? What damage has happened underneath the car where the plastic is damaged? Is the car a clean title, or has it been in an accident? Do you have the ability or know someone who can put the car on a lift or raise the car up on stands to look underneath?

 

If 2 different dealerships can't identify the problem, it's probably related to the accident and shoddy repair work.

Trade it in for a new prius

 

What codes did they pull at the dealership? Have you looked in the inverter reservoir to see if there is turbulence? The inverter pump is right behond the driver side headlight, so some front end damage may have caused some damage to the pump. Is the plastic intact around the wheel wells? Do you have an OBD2 reader so you can monitor some specific parameters?

Unfortunately cars that have been in accidents can have many causes for issues. When the previous owner sold the car to you, did they have any pictures or description of the damage?

As for the water, from your description it sounds like water is getting to the HV wiring in some form or fashion. Since you have had it up on a lift before, IMO it would be worth investigating all the orange wiring visually to see if there is any damage to any of the wires. A drivers side accident with hood and visual defects could mean they got the inverter or a wire behind it. Visual inspection for now, but if you see something exposed, do not touch as there will be 220 D.C. Volts behind it. If you are going to perform intrinsic work in the orange wires, the orange safety plug on the HV battery will need to be pulled prior to work.

 

Can you get clarification from them: did they see damaged high voltage (orange) wiring? Can they show you the damage?

If yes, and considering this happens when it rains, it sounds like they are making headway.

 

I haven't seen any specific trouble code in this thread yet, and that would be helpful, but post 1 paragraph 5 does say "high voltage leak" so I'll go with that.

Searching around PriusChat forums, you can find a procedure for narrowing down where such a leak might be. The basic idea is to clear the code first, then take note of when it comes back. This is trickier when it's intermittent as in this case, but maybe you can drive through enough slush to get a code that comes back right after clearing, and then you can follow the procedure.

If the code comes back when the car is only ON (not READY), the leak must be within the battery. The system main relay is open in that condition, so it can't be anywhere else. (Unless there's also a fault in the SMR, which should have its own code.)

If it comes back when in READY, it could be in the cabling from the battery forward, the inverter, or the MGs. If you can shift to N fast enough, and the code comes back in N, the MGs are out of the picture, and the leak is in the cable or inverter.

The cable runs along the outside bottom of the car part of the way, where it could possibly take physical damage allowing water in. It's easy to locate down there, it's orange.

Careful about touching it. Under normal circumstances, with no leak codes detected, it won't hurt you (the orange covering is insulation, after all), but in your case the computer's already telling you there's a leak somewhere, so normal rules don't apply. Keep a respectful distance unless the car is OFF (for an extra margin of safety, pull the service plug).

Other places water might intrude could be the gasketed entrances where the orange cabling enters the inverter or the MGs. You've got a Gen 3, so the orange cabling over to the air conditioner compressor is also a suspect.

You could (with the service plug out, natch) disconnect the ends of all of these cables, isolating them, then test with a megger between each conductor and the shield layer around it. Maybe with some salt water spray going.

If the megger finds some conductivity somewhere, you could then do a close visual of every inch of that cable, and you might spot a nick or gouge somewhere.

That would give you the satisfaction of finding the culprit. It wouldn't be necessary to the fix: Toyota doesn't condone any attempt at repairing the high-voltage wiring. If the megger finds a fault, you just replace whichever cable assembly the fault's in.

In the parts catalogs, I think the one from the battery forward to the inverter has the not-very-obvious name "frame wire", for some reason.

-Chap

 

You would love for it to come back when the car isn't ready. A leak inside the battery will likely clean up with a little boric acid/water scrub. Nothing else is likely to be that cheap or easy.

I wish I had added above ... if you do end up disconnecting any of those cables, please be vewwy vewwy careful to re-torque those connectors exactly to spec.

-Chap

 

Hi
The write up and reply were very informative as I was searching for a solution to my Check Hybrid System problem. In my passion to clean my Toyota Prius 2010 to its thread , I forgot the location of the Hybrid battery and poured soup solution on the covering fabric to wash it. Some water also seeped into the floor in washing of seats. Later I got the master warning light( yellow triangle with sign of exclamation) and the Check Hybrid System message. Pressing the display tab I get the mfd but after 5 seconds gets replaced by the message. The car is now dry. I can drive it as it shows ready in a corner instead of in the centre. The gear display is also not there. The engine starts and shuts off too just like normal. I have not driven the car far for fear of some damage. I tried resetting the code by three switch ons and offs but no good. Planning to disconnect the negative of the 12 v battery, but have no SD card and probably will have a dysfuctional W60 navigation/sound system.
Will welcome any advice. From my study I believe one of the safety device like CCID or ground fault monitor or relays were activated due to drenching of battery. Where are these located and do they auto reset after water goes away.

 

Greetings,

I would try to get a copy of Techstream and then load it onto a laptop. Techstream is what Toyota uses to pull codes on their products.
Most code readers only read basic engine codes and will not pick up on specific codes related to Prius.

Once you have the Techstream you will be able to pull all codes. Make notes of any codes you see, then try to clear all codes. Wait a day or so and then try to pull codes again. If no codes, no problemo. Simply observe what is going on. Once you finally get the same code or codes coming through the Techstream, then do a google search on those specific codes. Most google searches will come back to Prius Chat and hopefully give you some track to follow to solve your problem.

Best of luck to you and yours and Welcome to Prius Chat!

Ron (dorunron)

 

Keep in mind the high voltage is protected by GFI circuits on -both- positive and negative leads. A leak to ground (chassis) from either will trip off the high voltage relay in the battery pack. So you don't have that. It doesn't sound like a high voltage leak is the problem to me.

It's possible there is a water leak at one of the connectors on the inverter, letting water into the connector pins. Some water can eventually get underhood and get sprayed around by the fan or air movement.

 

I disconnected the 12 volt battery negative lead for hours and reconnected it. Now the message " Check Hybrid System" as well as the warning light are gone. However half of the dash board lights like transmission mode, fuel, speed and others are not coming on. The hybrid display also seems weird with engine running electric motor and motor charging battery etc. The car has ready sign towards one end of the dash board and I can move it though there seems to be some problem in power steering. Have checked a number of fuses , they all were ok. What can I do to sort out this problem. I have no adv OBD equipment or gadgets. Should I disconnect the hybrid battery for a while by pulling out the orange plug? Will it reset the relays and computer? Is it safe to drive the car to a workshop with display showing unnatural sort of power transfer. Will appreciate a simple answer.

 

Ron , thank you for your welcome note

 

In this case, sorry to say, a simple answer would probably not be the helpful kind. If you don't have any OBD-reading gadgets, your best path forward is probably to acquire one, or visit someone who has one. Any effort to troubleshoot without the codes is likely to be more complicated and/or expensive.

-Chap

 

Check also for chewed up wires from underneath. Rodents love the Orange wires. If exposed in the right areas, they could easily be getting wet when normally nothing does, even when plowing through water.

 

I went to someone who cleared the codes, yet the meter display was not coming. We thought that some water had seeped into the meter area and hence made a controlled spray of carburettor cleaner at the joint in the dashboard, avoiding the plastics. In seconds the display appeared and is showing fog at the lower side. Hopefully it will go away with time and I don't have to get it cleaned with the exercise of accessing it, dismantling the dashboard. Lesson learnt for the benefit of all, NEVER BE LAVISH WITH WATER ON THE DASHBOARD. ALWAYS RESTRICT YOURSELF TO LIGHT WET CLOTH TO CLEAN IT.
Everything in the car is now normal and I have huge relief. Hardly spent any amount on it but lot of anxiety as the car never bothered me for anything for the last three years and I am so very happy with it. Thanks to everyone for giving your invaluable comments. learnt a lot in the process.

 

I have 2010 Toyota prius base , have same issues that when i drove it in havey rain and on stop sighn my prius check engine and hybrid light comes on and it not happen in short distance it happens when I drove car for an hour or for 2 hours . the car never been an accident before, or no any visible damage.
any solution.......
Thanks

 

I know this is an older post, but this problem will come up again. I had a 2010 with the same problem. Heavy rain and then the P0AA6-526 code gets set. I DID find the problem. The high voltage wiring going to the transaxle was worn (or chewed) through and grounding on what was remaining of the shielding wires. Just had to know where to look to find the problem as once I removed the left front wheel, I could see the problem easily.

 

I noticed that point when I was rustproofing the front end (on our '10), visible through the front/left wheel well, as you say. The silvery mesh was rusting up nicely, down low and exposed to salt spray. I painted it with boiled linseed oil, hopefully still ok.