parked in mud and now electronic brake system inop

Yesterday there was a huge rain. Our 2009 Prius couldn't park under the carport (on slab) as we would have had to drive a ways through really soft water-logged ground in front of it. So the wife left it parked on our circle drive driveway, which stays harder than the ground elsewhere, as there is still some caliche left on it. So an inch or so of mud was on all the tires and even more mud on wheel wells. We are on a slope, so I am sure that water never got up to the underside of the car.
Today I go to drive it---fortunately it was not stuck---but have the sonalert tone going off, the red brake warning light on, the ABS light on, and the VSC light on! I was hoping it was just an accumulation of mud blocking a wheel sensor, so I took it to the car wash and washed the inside (primarily) and outside of the wheels off. Then realized that mud is non-ferrous,so it shouldn't block a wheel sensor signal anyway. I do have an OBDII code reader.....might it be able to read brake system trouble codes on Prius? This surely is induced by mud or moisture.....what would it likely be? It has always been perfect as far as brakes until yesterday, when it got a huge amt. of mud on tires. Could maybe water accumulate in one of the sensor harnesses, effectively shorting it out?

 

How do I pull blinking codes and interpret them? I can read Prius hybrid system codes this way as well?
It has an Optima battery, the original was replaced only about 10K miles ago (56K miles).
Found out that the car was driven during or right after the big rainstorm, and there was shallow water (an inch or so) completely covering a section of the road a ways down from our place....so it might have gotten drenched then. But the car has had more than a day to get dried out if there was moisture like trapped in a wire bundle.... but the brake system is still bad.
Actually the brake system has not *quite* been perfect. A few times , when I hit a rut, I noticed the yellow brake warning light flash for just a second. Like a bad connection somewhere. But brakes continued working fine. So I am thinking perhaps the yellow brake warning light is an instantaneous indication, while if it comes on and stays on (hard fail) , the other lights are set on, too. I am hearing horror stories of electronic brake system repairs costing $2500 or more....such as $1600 for a new brake actuator, plus 900 for the labor. Nobody wants to touch this car except Toyota dealer! Am almost sorry I bought it.
Above all I want to stay away from Toyota dealer, I can do a lot of car repairs myself, but I am kind of hamstrung without the scanmaster diagnostic tool. The only place locally I can get it worked on here is the Toyota dealer, and just to get code diagnosis they charge $100!

 

I found an article on internet that said that you can get blink codes for the brake system by jumping pins 3 and 13 in OBDII conn. But this did not work. It did not change anything on dash display. I can't even get to square 1 if I can't pull codes!
I checked to see if brake fluid reservoir was full, and it is. Here is a little more on symptoms: With car on, not pressing on brake, it makes a whirring sound like an electric pump every 10 sec. for abt 2 seconds. What is this, possibly this is the accumulator pump? It seems to be coming from back of inverter area.
If I press on brake, the whirring pump sound starts up, and goes on for about 20 seconds, then stops. but also, there is an odd erratic clattering sound, I don't think its coming from anywhere in the eng. compt. Seems like its around the front right of the car.
I did take all the wheels off and inspect the sensors. The rear ones appear to be an integral part of the spindle, so all I could do was check for damage to the signal cable. I removed both front sensors and cleaned them off, but they were really pretty clean as found, no crud build-up of any kind.
And last, I think it was really the traction (stabilization?) yellow warning light that I saw flash a few times when hitting a particularly bad rut....that's the one to the left of the yellow brake warning light....and it is just about the only light that is not illuminated now.
I am the second owner, got it when it had about 50K miles on it. I hear that Toyota will warranty the hybrid system to 100K (in Texas). But the brake system is not warrantied with the same deal? I think its not. Its still got well under 100K miles. Thanks for the help.

 

OK.....I had some bum info at first, its pins 4 and 13. Your link was correct, with I had seen it to start with. So I have the codes now:

yel. brake warning /exclamation mark: 41 54 36
ABS: 42 31
VSC: 43 45

I am in Mathis Tx., the closest Toyota service is 50 mi. away in Corpus Christi. A bunch of crooks.

 

I should add that I checked the battery voltage, its good...12.7V. So I disconnected it for a couple of minutes and then re-connected. But it made no difference. Upon starting, it is still showing all the same warning lights.

 

When I checked the RH front sensor, I noticed that someone did a repair to this sensor cable, there are two crimped butt spices that had been wrapped with black electricians' tape. This cheap wrapping could have allowed moisture in and held it on the splices, but they were dry. But the connections seemed to still be solid, as I could pull on the wires and they did not come out. I will redo-those spices and see what happens. Can the sensor be checked, like for continuity or ohm value, with a Fluke? I have a scope, so if its still no good when re-spliced, I could check it by rotating the wheel I guess, if I had some info on correct signal.

 

Oh...well, Its not a portable scope. And from Rockauto.com, this sensor cost 97.00! Since you say it develops a sine wave, it must be a variable reluctance-type. These things are not likely to go bad, as there is nothing inside but a coil and pole-piece. I looked at the cable further up, all the way to where it goes into a big bundle underneath the windshield washer reservoir, and visually it all looks OK. Tomorrow I will definitely remove the cheesy repair with the butt splices, and make solder spices with heat shrink, and see what happens. It's also bad practice to use electricians tape like they did! I took the connector apart that is at the top of the wheel well behind the fender liner...with my Fluke it reads about 7K ohms. But I don't know if that tells you anything about whether its good, probably not much. After replacing butt splices I will check again, but I think its going to be the same,there is sure no open conn. at either butt splice. I have a Bentley manual for the car, hopefully I can read all the way from where the wiring diagram shows it terminates...(probably at an ABS module?), so get the whole circuit checked.
Its kind of a hassle, but I guess I will swap left and right sensors and see if the code changes to avoid wasting $97.00. Its just a bit of a trouble to get BOTH liners dropped down. Do you know of any cheaper source for the ABS sensor?

Yea, I ordered a Mini-VCS! Many thanks for the heads-up on that.

 

Success! At some point, possibly when I high-pressure washed the insides of the wheels, I fixed the problem. But the system had not been reset. In another thread here on Priuschat, I found the procedure for resetting the ABS system. You pump 8 times on the brake pedal within 5 sec, while you have pins 4-13 jumped, car in Ready mode. This turned off audible alarm and the fault lights, and brakes are back to normal.
You guys are awesome, saved me a lot of $$$$!