I have had my current 2010 Prius hatch V for about 6 years now, the car has been mostly worry free till early this year. The issue started coming up as " Check PCS system", this would happen mostly when I would press the brake peddle while the Dynamic radar cruise control would be on. After that you cant use the radar cruise control unless you turn the Cruise control off and back on again. The issue somewhat disappeared when the weather started being nice again, so through the summer it was somewhat ok with occasional warning here and there, till earlier this month. The same warning would come back on and eventually it started giving me the yellow triangle along with PCS, Brake, ABS, TCS warning etc. The whole dash would light up like a Christmas tree, how fitting this time of the year. The dash would reset itself eventually and or if I shut the car and turned it back on. The lights indicated an issue with the ABS system but more worryingly I'd loose brake booster pressure. The car would turn into an old 60s classic with no brake booster pressure, scary as you'd never know when you'd go from regular brakes to boostless brakes, if thats a word. No check engine light by the way, this would happen very randomly, only thing that would be common every time would be bad weather. I hooked up a snap on fancy scanner from a buddy of mine and went digging in the ABS system, following are codes that I got, at first I thought it was the speed sensor but during a live data run all sensors were reading fine so I didnt think that was an issue, unfortunately I should have done the test on the highway as thats when the whole issue would usually come up. I did some research and thought the worst that the Prius might need a new brake booster/pump. As most recently the ABS started kicking in without any need of it on dry tarmac. I limped the car into the local Toyota dealership, paid the diagnostic fee and braced myself for the worst. After the diagnostic they recommended a new left rear wheel bearing/hub as its got the speed/ABS sensor built right into it along with the cable as the contacts were corroded due to age/salt etc. Along with that a new set of front rotors/pads were also recommended. Quote was around $1000 for the hub/wire and $500 for the front brakes. I gladly paid them the $129 diagnostic fee, bough the parts through my commercial account with them, spend 8 hours yesterday and installed everything. I ended up changing both rear hubs/wires as when I did the scan there were speed sensor codes from both sides in the history. Most of the time was spent fighting with the hubs as the corrosion over the years havent been kind to them and the car. I had to macgyver the whole thing and use an old HD bearing puller without the jaws to leverage the hub off of the chassis. Drove the car 50 miles since the install and everything is copacetic. So if you have a check PCS warning or ABS warning I'd advise on checking if the speed sensors are working fine and if they have any codes. Unlike most cars the speed/abs sensors are part of the hub hence the hub has to be replaced in order to replace a faulty sensor. The pins on the connectors to and from the sensor are really tiny and are open to the elements. Its not a question of if they'd every go bad, its a question of when, especially if you live in the rust belt areas. I'd highly advise on investing in a good scan tool as well, especially if you do your own work. I am on the hunt for one now as I can always borrow my friends snap on but I'd rather have something in my arsenal as well for diagnostics. By the way the car has 282k miles on the odometer.
Yep facts all wiring needs be communicating with systems . I used to be in Western Mass. So I have extra hubs in shop loaded w ball joints bearings etc so swap out is fassst.almost takes longer to get car up and wheels off he he
I guess my excitement was short lived, the stupid "check cruise control" warning is still coming on when ever I press the brake peddle while the cruise control is turned on. The brake booster/tcs/pcs issue is all sorted though, now I have to go digging again to see if I can rectify this cruise control issue. The cruise control works fine, both the adaptive and conventional cruise, its only in adaptive mode that every now and then if the cruise control is on (on but not set) and I press the brake peddle it shows the "check cruise control" warning. Turning off the cruise control and turning it back on resets it and lets you use the cruise control again. Looking at the screenshot of the fault codes from a week ago, I wonder if the C1241 code is pertaining to this matter, I am going to hook up the snap on tool to the car again later and see go fishing for a code with it. Here is a short video of the issue, dont mind the dirty dash
I had the same issue with my Prius. I fixed it by replacing the brake light switch located under the steering wheel. The part only cost $20, and it has worked flawlessly since.
That seems to make sense Is that switch just a single off and on contact or does it have multiple steps to the switch or multiple plugs I haven't looked I don't have adaptive cruise but that seemingly would make sense and probably be easy to check too.
I just had this happen today. Got the "Check PCS System" warning, plus the red triangle and tons of other warning lights. I also lost my brake booster. I was about 100 km from home and after test driving in a neighbourhood I felt like I could stop the car if needed, it just would have no braking through most of the brake stroke and then grab hard at the bottom. So I drove home carefully, luckily it was all highway driving and not much traffic. Once I got it home I thought it could have been a 12v battery issue since my battery was running low. Replaced it with a new one fresh off the trickle charger and I still have the same "Check PCS System" error. My question to @Leafscheifs - do you really think replacing a brake light switch will fix all of this? Why? I suspect it could perhaps be the issue with the wheel speed sensors that are part of the hub. Strange thing is I just replaced the right rear wheel bearing a few months ago. Perhaps it could be the left one has gone bad? Or the connection at the right one wasnt sealed properly and is corroded or disconnected after they did the repair? I lost my OBDII scanner so I also need to order one and run the codes. If anyone has any ideas what to do here let me know. I really hope to DIY fix this, or at least DIY diagnose it before I bring it into the dealer.
Well I would definitely think before you can do all that you will need a appropriate scan tool to see if any of these things are thinking are even present like the front wheel sensors taking on water I thought those plugs were pretty well sealed and high up The wheel speed sensor plugs are usually sitting up by the strut spring so they're way up in the wheel well behind the wheel well interior black plastic trim that covers everything in the wheel well electrics and other things up there of course in a lot of these cars some of those are missing but I wouldn't think water even flogging up off the tire hitting the connector for the wheel sensor would be much of a thing The water would just run off and head to the ground unless somebody has dug the rubber grommet out of the plug just because those gray plugs do pretty good take a connection and one of those gray plugs from an old sensor with both pieces mated from the car and the sensor and stick it in the sink full of water and then pull it out let it sit in there 10 minutes if you like then pull it out shake it off with just your hand set it on a paper towel for a second so the residual water on the exterior of the two mated pieces can drop off onto the paper towel now carefully pull the plug apart and take your magnifying glass and look in the plug I bet you don't see any water and the rubber seals that are in the two pieces or in the female piece are there gray orange whatever color they are white and they do pretty good at that sealing business.
Okay I got my OBD II reader. The car is returning no codes. Error still persists with the "Check PCS System" message plus the ABS light, other warning signals "(!)" and the triangle with exclamation mark and traction controll off liight. The brake booster still doesnt work. I also tried pressing the PCS button under the steering wheel multiple times and that seemed to do nothing at all. So if the car is returning no codes with a cheap OBDII reader and the OBD Fusion app, will Techstream tell me if there is there an issue with the wheel sensors? I am looking at getting techstream and the mini VCI. I also think I now need to figure out where these wheel speed sensors actually are on all 4 wheels and visually inspect them. Tombukt2 - thanks for your reply. Its a bit hard to parse all that out (I think you are using voice to text)? But I think I pull out the main points. I did pressure wash the car two days before this started happening, including generous blasting around the wheel wells so maybe I did something there?
Wheel well liners out of car or missing.? The plug for these sensors is almost your waist high mounted the sensor is about ten inches at best off ground mounted. . It's the only wire going to each hub.
Okay - update on this. I got a reading from techstream. Tombukt2 - No the wheel well liners arnt missing, but one of them is a bit loose and water from the pressure washer could have gotten under it. I will inspect closer and report back. Got these two codes: C0210 - Rear Speed Sensor RH Circuit C1238 - Foreign Object Attached on Tip of Rear Speed Sensor RH So I am assuming either the sensor is messed up, unplugged, or covered in dirt? I am assuming that if it was just foreign object there would not also be the issue with the circuit. Next step I will pull the rear right hand wheel and inspect, and also maybe pull off the cover.
Oh, one thing I forgot to mention. I JUST had the right rear wheel bearing assembly replaced by a mechanic two months ago because the bearing was making noise. We sourced a non-OEM bearing assembly because it was cheaper. It looks like the sensor is included in the bearing assembly. So I suspect that new sensor has failed pre-maturely, or there is a wiring issue, or it was not reconnected properly. I also read that a bad bearing can leak grease and cause the "foreign object attached on tip" error. But as the bearing was just repalced that is unlikely. I will report back if I can see anything odd when I pull off the rear wheel.
Could be the mechanic damaged the speed sensor connector? The connector is a royal pain, just trying to remove it can end up breaking it, so the locking mechanism is shot, it's just relying on friction. Or if if the mechanic didn't disconnect prior to bearing removal, it might have stressed the wires as it popped off.
You are re-living my experience. my (now former) mechanic had used a very cheap replacement bearing. It blew out the inner grease seal and fouled the sensor with oozing lube about 5,000 miles after installation. I cleaned out the mess, installed a new genuine Toyota bearing, cleared the errors and the car's been perfect since then, maybe another 10k on. I will still use some aftermarket parts, but the last few years have been a lesson in how quickly the rules change and which categories you can still trust to get on the cheap. Good luck!
