Car Wash Caused Hybrid System Warning

Well, I guess anything's possible - those darn electrons move pretty fast! But if that were the case, I would think it would have thrown more than just one code (ground is gone - and how many sensors must depend on it, or would get "flagged" for being at 12V instead of ground?)

All good theories...but just like how many licks it takes to get to the center of a Tootsie Pop, "the world may never know"........

 

I routinely use a touchless wash and have had only one problem: the last time the outdoor temperature sensor got stuck at 68 degrees (water temperature?) and didn't start rising back to actual ambient temperature until about 15 minutes later (including about 10 minutes at interstate speeds). After I got home (about 20 minutes), it had finally risen to approximately the proper temperature, and it was seemingly back to normal after that.

 

Coincidentally, I was asked to look into ISO7637 at work a few days ago. It's the spec that covers voltage spikes on the 12V system in cars (or 24V for commercial vehicles). Cars are apparently very nasty places for electronics. All of the possible spikes are supposed to be from the various motors starting and stopping under various conditions (fans, alternator, etc).

One of the nastiest specs in there is that the electronics are supposed to tolerate a train of 2ms -100V spikes (yes negative with two zeros). Not that I recommend shorting the traction battery to the 12V system.

 

I hand washed my 2010 Prius yesterday, and several times the car would beep whenever I ran my wet sponge over the driver side door knob. No harm done though, and everything was normal after I finished washing it.

 

Jim,

Same thing happened to me when washing mine. I didn't have the FOB in my pocket but close enough to the car to note it's proximity.

Once I placed it farther away, no more beeping or locking or unlocking happened. A learning curve.

Thanks for your post as well...

 

The thing you have to realise about voltages is that they are all relative. There is no such thing as 'ground', only a reference point to which other voltages are measured. The other term for voltage is potential difference. By convention, the vehicle's chassis is considered 'ground'. Because the aux battery's negative terminal is connected to the chassis, the potential of the connections to the positive terminal are said to be at 12 volts.

The high-voltage battery's positive and negative terminals are completely disconnected from the rest of the car, the return path being a second conductor. The negative point therefore could give any reading at all compared to the chassis if you read it with a voltmeter.

'Ground' is really a term from transmission-line systems such as power distribution, where the Earth itself (i.e. the planet) is used as the return path.

Poor connections to 'ground' on one sensor, compared to the ECU that measures the value, can cause sensor values to be wildly out of range, because the two ground points have a potential difference between them (connecting a meter across the two points would show some voltage difference). Some of the car's sensors (e.g. coolant temperature sensor) are connected at two points, to provide a good reference ground, rather than being connected to the chassis. Some ECUs have multiple ground points and therefore can even show incorrect voltages within the ECU itself. An ECU fault should be diagnosed first by checking all relevant ground points, in my view.

So, if there was a short between the battery positive terminal and the chassis, the ECUs would see that as a reduced voltage on the power connections - likely they'd momentarily switch off.

 

Went through an auto carwash today after filling the tank but forgot to replace the gas tank cap. This is a high pressure water jet wtih no brush type of car wash. I wonder how bad it affected the car. I have the gen III prius. Appreciate any feedback.

 

Oh no!
Would be best to have the tank drained and then refill. I wouldn't drive the car until the water was removed. That's my opinion.

 

Thanks, I will do that first thing Monday. I should be able to drive for few miles to the dealership since it's got full tank right now.

 

Except the water might get into the fuel system. You can't remove the filter in the prius, it's all integrated inside the fuel tank, pump and all. I hope very little has gone into the tank.

 

Not a good idea. Water will pool in the bottom of the tank, no matter how full it is, and possibly slosh into the fuel inlet line. Fuel injection systems do not like water.

Best call your dealer and ask them what to do. If it were mine, I would not drive it without a mechanic's approval.

 

I've Toyota Aqua 2012. Yesterday, I got my car washed from the service station with diesel spray in engine room. Just after having it washed, the car started having issues. Initially it didn't start at all. After trying 2 to 3 times, it finally started but AC was not working and 4 symbols were appearing on the dashboard screen. Engine check light (fuel pump symbol), hand brakes light, traction control and Hybrid warning light. Was so upset with this. Talked to my mechanic and he told me 'Don't Worry'. Just park the car in sun with opened bonnet for approx 2 hours. I did the same thing. After 2 hours, 2 out of 4 symbols had gone and AC started working but Hybrid warning light was still appearing Finally I got an idea...I took a hair dryer and tried to put some hot air around the plugs on hybrid synergy system in the bonnet. After doing it just for 5 mins, all the symbols had gone. So guys, if this happens to your cars, don't go to the mechanics immediately. They will charge heavy amount for removing the fault....

Regards,
Fakhar Imam (Pakistan)

 

welcome!

thanks for the tip! this is why we don't advise ad hoc cleaning of the engine room.

 

Be sure to check if your under-engine underbody panel is there. Alternatively, the underbody panel may be there but the oil change door may be missing. Both are a common occurrence with the Gen3 models.

I'm not sure I would trust a touchless car wash if either of the underbody panels were missing. Many touchless car wash systems blast water upwards as you drive forward to attempt to clean under the vehicle.

As for myself, I use a tochless car wash frequently without issue.

 

After a deep cleanse car wash that involved all the rear seats and whole engine area being steam cleaned the hybrid warning light came on. After 2 days it dissappeared just as I was about to book into a dealer. I guess one of the sensors got blocked or wet.

Hope this helps others.