Did I break my Prius while "fixing" it? Brake/ABS/VSC lights on....

Hello all,

Today I replace the coolant flow valve to cure a 1121 code, and related check engine light in my 2009. After following the advice of a couple of threads on this site I was able to do that job with little coolant loss and no particular problems. At least that's what I thought.

On switching on the car to clear the check-engine code, I noticed the Brake & ABS & VSC lights were on. This was surprising, and concerning. I cleared 1121 code, and that seems all good, however it does seem that the brake computer is unhappy. It also seems that braking is a bit different too, which is disconcerting.

I checked the voltage on the 12V system. That seems ok, at about 13V when in "ready" state and about 12.6V with the car off. I tried to reset the ABS light with the OBD2 jumper and pump-the-pedal technique. That seems to work, very briefly, and then the light returns.

I don't think I dislodged or damaged anything while working on the coolant valve, but it is a bit of a fiddle to deal with, so maybe I did. What is there in that area that could upset the braking system? Wiring for a sensor on the left front wheel perhaps?

I've ordered a mini VCI to see if I can extract some more information. Meanwhile, what do you all think could be causing this? Maybe the braking system has died on the same day, by sheer coincidence, but that would seem a bit unlucky...

Hoping for some wisdom and suggestions.
Thanks!
Doug

 

Ah, sorry, I forgot to mention that I did that. I unhooked 12V negative for a few minutes. No change.
Doug

 

It seems that the speed sensor wire exits the wheel well really high up, more like in the region of the main fuse/relay box.
I've been looking again today, with a good flashlight from underneath and above, and I am not really seeing anything that seems like it might be involved... There is what appears to be a crash sensor below the valve, and it might have got wet etc, but the air bag system is not complaining. There are other transaxle etc related wires, sensors etc down there, but I don't see anything that looks particularly vulnerable to damage, or related to braking.
Are there any more detailed diagnostics that I can extract before my mini VCI arrives on Monday?
thx
Doug

 

Well, I dug out my trusty Fluke 87 and gave it new batteries. A careful voltage measurement shows 12.49 switched off, and 13.92 "ready" and, 13.98 "ready" when the ICE started up and ran for a bit. There did appear to be some flow visible in the inverter coolant reservoir, so I think that pump is running ok. I could also hear a quiet "pump-like" sound.
Are these voltages consistent with a properly operating inverter & DC-DC converter?
doug

 

Coolant's good. I've not got the red triangle, just the brake-related stuff. Thx.

 

That's very interesting. I used ramps on my sloping driveway, so the front of the car was significantly raised. I wonder if that is the common factor with your dolly- towing situation.
I'm traveling for a few days so I won't be able to do much til I get back.

 

Ok, I'm back from travel and have got Techstream working. on the ABS/VSC/TRAC section the codes I find are:

C1203 Engine Control System Communication Circuit
C1345 Not Learning Linear Valve Offset

What's the most sensible next step? Just clear these codes and see if they come back?
regards
Doug

 

Well, I used the techstream program to run the recalibration of the Linear valve. That seemed to go ok, though I had to leave the parking brake off (as instructed in the on-line manual, but in contradiction to the instructions relayed through the techstream software).

So far, after a quick drive around the block, all seems well. The warning lights are all out and the brakes seem to be working normally again.

This is good, but what might have caused this???

Doug