Wrench light, and weird braking that came with it.

[Bobo]

I saw one other post about this, but there was no resolution there so...

Last night, my wrench light came on, along with the 'see manual' message. The car still drove fine, but DID exhibit some weird behavior. When I would lightly tap the brakes, the regen braking wanted to bring the car to a quick stop. Normally, I can tap the brakes gently, and the regen thing will go to work, braking the car in the process, but not to the point of SLOWING THE CAR as if I'm trying to avoid collision. I could not use regen braking last night on the way home. I had to wait until it was time to stop before pressing the brake.

This morning, the wrench light was gone and the car seems to be driving normally. I did check the engine coolant and the inverter coolant and they are both riding the min lines. I will add coolant today. Could a temporary overheat problem have caused this symptom? Also, for the last week or so, the low tire pressure light has been on. I will make sure to take care of that today as well. Oh, and I don't know if this could have anything to do with it, but the other day, I had to slam on the brakes to avoid hitting some shmuck who decided to stop on a dime for no apparent reason. I've only had to quickly apply the brakes in this car a handful of times, and each time, it didn't feel like a regular ICE car. It feels more like it's grabbing. Not 'locking up' per se. But grabbing. A little thump can always be heard when QUICKLY applying the brakes. AFAIK, this could be normal. And I hope it is.

----edit-----
It might be helpful to describe the environment when the issue occured. Thanks Murphy for reminding me of this!
I was driving on the interstate, at about 75mph or so when this happened. It had been raining also so the roads were a little wet. JUST BEFORE I noticed the wrench light, I had driven over two rough patches on the highway.
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Any advice or suggestions would be appreciated. I did search. I found one thread that pretty much exactly described the symptoms I experienced, but it only had a couple of posts. In that thread, the OP said the problem came back after 10 minutes. I just drove it up to the store and back, so... I'm gonna go get some coolant and fix the PSI thing and then take it back out on the highway to see if it the issue recurs at speed.

Edited October 26, 2019 by Bobo

[murphy]

Regen braking only works if both front wheels have traction. If either front wheel starts to slide regen braking is instantly gone because of how a differential works. When it happens it feels like the car is accelerating. It is not accelerating but the instant lack of any braking convinces your brain that you are accelerating. The most common place for this to happen is when one front wheel goes over a sunken manhole cover during regen braking.

[Bobo]

Ok, so I probably should have added this, but I didn't really recall it until your post!

JUST BEFORE the issue happened, I had driven over two 'rough spots' on the interstate. I would have normally driven around these spots, but it was dark and I didn't see them in time. It was only moments after I drove over these spots that I noticed the light and the accompanying symptoms.

But my symptoms weren't a LACK of braking in regen mode. My problem was 'TOO MUCH' braking in regen. It was weird. Regen braking was wanting to stop the car quickly, which is uncharacteristic of what I've experienced in this car. Actually, as I continued to push the brake pedal further into conventional brake mode, the braking actually got LIGHTER for a moment before eventually getting heavier and stopping the car. I could also feel it when I let OFF the brake. When I would let off the brake, I could feel a short pulse of heavy braking as the brake pedal passed through the regen range as it came back to resting position.

Edited October 26, 2019 by Bobo

[suj]

I am having same problem, also my inverter coolant is low. How did you solve the problem if you did, it would be great help.