VSC, ABS, (!) and emergency brake light on

It sounds like your dealer wants to replace the brake actuator assembly as well as the skid control ECU. It is likely that one or the other part has failed but not likely that both have failed.

I would start by replacing the skid control ECU since that is something you can do yourself. You will need to seek dealer service dept help to initialize the system and perform the zero point calibration.

To learn more about what is required you can obtain repair manual info at techinfo.toyota.com

 

Thx Patrick
I purchased a 48 membership to the techinfo website and have played around the website but since I am not very familiar with it, I am unable to find the info needed to located the VSC Module as well as instructions on how to remove and replace.

Are you familiar with the sight that you can maybe provide some insight?

Thanks

 

I haven't logged on the site for a while. However try looking for:

- electronically controlled brake system
- skid control ECU

 

Found them, very informative site, thank you

however I am a bit confused, when I was at the dealer they had the car sitting on the lift and they dropped it down enough to show me under the hood, they used a flash light to point out the so called VSC ECU, the location they pointed to was directly under the drivers side wiper area of the engine, directly behind the big bright orange plug, it has a barcode and some numbers that I am nly able to read a few numbers because the plug I just mention is covering it.
On the repair manual I downloaded from the Toyota site it shows the VSC ECU is directly attached to the steering column inside the car not in the engine compartment.

 

Okay nevermind, they were pointing out the brake actuator to me at the dealer, I found the repair manual for it. I hope that is not what has gone out because it looks like alot of work to replace, I dont even know if it is something I could replace myself

 

You could physically replace the brake actuator yourself but you would need to seek professional help to purge air out of the brake hydraulic lines since that requires the Toyota diagnostic laptop.

 

Hey Guys,

I apologize to post on an old thread, but I have similar problem to my Prius 2007 with currently 100k miles. So about 5 months ago when I went down a hill while slowly braking, suddenly the Emergency Brake Light, VSC, ABS, and (!) are all turned on. I tried to brushed them off until I finally decided to check the Prius to a Toyota Dealer a few months later. They didn't found anything and let me know to come back if the lights are on again (if I turn off the vehicle and turn it on again, the lights are gone).

Few days ago, when I brake slowly at the stoplight, all the lights were suddenly turned on again and I was near a Toyota dealer so I took a visit and let them see as a proof that something is definitely going on with my vehicle. Let me break the details below:
- They charged me $215 for a diagnostic check (I paid this amount already after a bit of negotiation from $250 and I think I am willing because the lights were turned on again and I was near a Toyota dealer so might just as well)
- They said I need to change the 12V Auxiliary Battery, part cost $200.
- And I need to change Stop Lite/Light Switch as well, part cost $90.
- Basically with $215 diagnostic fee included, they want to charge me a total of $600 (already with tax, etc).

I did the 12V Auxiliary Battery test:
1. Initial power button pressed, without pressing pedal brake shows = 9.8V
2. Second power button pressed, without pressing pedal brake shows = 10.5V
3. Final power button pressed, with stepping on pedal brake shows = 14.1V
Seems there is something up with the battery but in CHARGED/START mode it shows normal 14.1V so I still have no idea what is going on.

Also, my sister mentioned she saw one of the headlights at the back went off when she tailgate me so there might really be something wrong with the Stop Lite/Light Switch.

Lastly, I do a bit of research changing 12V Auxiliary Battery at dealer cost $200-$300, so a total of $600 might be the appropriate price after all for fixing these two parts.

Hopefully I can get some feedback from you guys as I am not a tech-savvy but I just love this car like all of you here. Thanks again for your time reading this, I really appreciate it! I will update soon hopefully if I find anything new.

Kind Regards,
Steven

 

Hi Steven,

1. The 12V battery needs to be changed now. The presence of 14.1V when the car is READY just means that the DC/DC converter within the inverter is working properly. The first two voltage readings you reported show that the 12V battery is near dead.

2. If at least one of the brake lights will turn on when the brake pedal is pressed, then the problem is that you need the other brake light(s) to be replaced or the associated wiring to be checked - not the switch.

3. Make the Prius READY and look at the inverter coolant reservoir. Do you see fluid turbulence within? If not, the inverter coolant pump has failed and that is the root cause of the ABS, VSC and ((!)) warning lights.

 

Again Patrick has nailed it. This 12V battery is a zombie, the living dead. It sort of acts like it's living but is really dead and will next leave you stranded where it will cost you a towing bill, the cost of replacement, in addition to lost time. It likely needed replacing the first time you had this problem. Depending on how much you are willing to pay, you may discover you can replace this yourself. It's not difficult and can save you some money. Since this battery is in the last days of hanging on, it can cause many troubling issues. Replacing it may eliminate some others.

But check the turbulance in the inverter coolant reservoir. If there is no turbulance of the coolant, the inverter coolant pump needs replacing. I believe this is a recall item and would be a free dealer replacement and should be done now.

 

Hi Patrick,

Thank you, your information and answers definitely helped erase some of my confusions.

1. Yes, I think it is wise to change the 12V Auxiliary Battery.
2. I gotta ask more questions Stop Light Switch like you said, they might be okay after all.
3. By READY, I assumed it is pressing the power button while holding the brake right? In that case, I don't much of turbulence in the inverter coolant reservoir but the coolant definitely flows (kinda like a smooth river flow I guess?). I read your previous comment on other person and tried pressing the power button twice without pressing the brake and I do hear faint sound, not sure if it is the pump or the battery besides it (haven't hear an aquarium pump in a long while). On the other hand during the same phase, the inverter coolant reservoir doesn't flow or has any turbulence whatsoever.

I am bringing the car to the Toyota dealer again soon and ask further information I can get then hopefully let them repair what's truly needed.

Thanks,
Steven

 

Hi Steve,

Thank you for your input, I definitely check if the pump is indeed a recall item. I hope I don't spend more money than is needed for these repairs );

Best,
Steven

 

Wow, I'm surprised to see how many people are having the same problem I've been having with my prius. I have a 2004 prius. I bought it 3 years ago. I had only had it for about a month when I started having the combination BRAKE, VSC, ABS and ((!)) lights go off. Since I had just bought the car, I took it in and they at first couldn't find anything. The lights would go on and off and Toyota couldn't find a correlation. In the 3 years since then, they have been going on and off; usually taking 3 starts for them to go off once they go on. A couple of weeks ago I was driving and they went on without me braking (normally they'd go on when I'd touch the brake) and they have not gone off in weeks. Toyota wants $300 to start diagnosis for this since its not under warranty anymore. I changed the 12V battery this past December, so that is not it. Any advice would be appreciated for a medic with little $$ to spend on car repairs.

 

1. Make the Prius READY, open the hood, and look at the inverter coolant reservoir for fluid turbulence. If you see this then the inverter coolant pump is working. Otherwise, a failed inverter coolant pump is your car's problem.

2. When the Prius is IG-OFF, turn on the headlights and look at them to see if they are bright or not.

 

Where is the Inverter coolant reservoir? I'm not a car girl and its like greek to me.

 

1. Make the Prius READY.
2. Open the hood.
3. Find the inverter on the right side of the engine compartment (as you are standing at the front bumper in front of the car.) The inverter has a large shiny aluminum cover.
4. Find the inverter coolant reservoir which is mounted on the side of the inverter, nearest to the engine.

 

The inverter coolant reservoir is the white container between the engine on the left and the inverter (large silver square object) on the right. The reservoir has pink coolant fluid. As Patrick said, with the car in READY, open the reservoir to see the pink fluid. You should see turbulence.

 

Just to resurrect this thread, but I would like to contribute with my solution.
Few days ago I forgot to pull out my ELM327 Bluetooth adapter from OBD2 port during the night. This must have drained the battery to critical level and next day I have warning lights on my dashboard during the driving.
I restarted the car, lights gone, but after some time coming back again. I played this game whole day with my car.
Checked the battery, it was 12.1V unloaded.
Next day ago I charged my 12V battery over night with battery charger to a full capacity and since then no more warning lights. I am aware that my 12V battery might be at the end of it's lifetime so soon I might have to buy a new one. I recently purchased this car so I don't know the history of the battery.

 

Note that if the car is off, there will not be any current drain from anything plugged into the OBDII port, as the 12V there is switched with the IGN relay. So I expect that your 12V battery is indeed close to the end.

(Not so, see below...)

 

I just did the double check and on my car (2008 gen2) there is a 12v when the car is off. Same thing with my Subaru Forester.

Here is the pic, car is off but ELM327 still lights the first LED.


SM-N9005 ?

 

OK. Mea culpa. I took a wrong turn on the winding, multipage wiring diagram. So pin 16 is on at all times.

Still, your bluetooth adapter will draw what, 5mA quiescent? It should not be significant if the battery is OK.