Citroen C Zero - Brake Trouble (Solved by Existing Recall)

we've owned our 4 year old c zero for four months now, and just as I've been crowing to colleagues about our 3000 trouble free miles, it's let me down big style.

At first the brake pedal just felt different. Then after a couple of miles the car would slow on the regen as normal, but the friction brakes would do nothing at low speed until they grabbed suddenly and the car ground to a halt. The nearside front wheel gets a lot of ABS activity as it stops.

We're now home about 20 miles later. It's still doing it and now sometimes the brakes are holding on as I try to set off. They then suddenly release after a while and the car shoots forward.

When stationary, if I pump the brake there is a bleep from somewhere in the dash too.

There are no warning lights and the car is otherwise fine. I'm awaiting citroen recovery but have never known anything like this in 25 years of driving. To say im disappointed is a massive understatement.

FWIW we've had heavy rain here in northern England, and I hope it's water getting into a sensor......but even so, it shouldn't misbehave like this.

montybazbaz, sorry to hear. The fact that you have no warning lights leads me to think that the computer thinks it is properly reacting to what the sensors are telling it. The proper integration of regen, hydraulic brake circuits, ABS, and nowadays the Active Stability Control system and brake rate detection and response, makes our little i-MiEV a computerized marvel (or curse, depending on one's perspective). Since your C-Zero is four years old, maybe some of the bugs had not been fully worked out and your speculation that perhaps a sensor is at fault may well be the case. Please do let us know what the dealer does to fix it (be sure to let the dealer know that you want to know exactly), and hopefully it won't magically start working properly when it gets into the dealer's garage. All the best.

It sounds like a wheel speed sensor is going bad. Should be a simple fix. My old Cavalier started randomly engaging the ABS under light braking. Had the codes read at Advance Auto, and found the right front sensor was bad. The dash lights would randomly come on while driving, regardless if the system engaged or not. A few years prior, the right front sensor was replaced, so the replacement went bad. I put the original sensor back on and it stayed like that until we traded it in.

The ABS control assembly is located in the front left of the car, so you'd hear noise there pretty much regardless of which wheel was being controlled.

Just done a test drive with the recovery guy. Confirms that its grabbing just as it stops and abs kicked in but was bemused by the fact it's an electric car. Brakes also held on when restarting.....does the car have a hill start assist feature !?

So a call to citreon beckons, and I'll see just how good the approved used car warranty is. Heaven help me....

Well thus is great. I've driven it to work and the brakes were still slamming on, making stops very rough and making the brakes squeal in protest. And then.....on the last couple of miles normality is resumed. Progressive, smooth braking with no squeals or other protests from the car.

And now I'm more annoyed. There was a definite fault....but i have nothing to show the dealer now. The only difference is this morning is dry ear and cold. Yesterday was a wash out. Has something dried out ?

it certainly does seem like a sensor/wiring issue rather than an actual mechanical problem with the brakes - here's hoping you can get to the bottom of it if it recurs.

Many of our cars have been called to replace the vacuum brake booster

http://myimiev.com/forum/viewtopic.php?f=22&t=2234&start=10

It seems that some units had problems with (winter) salt, may be corrosion or so.

Your unit has been affected by the campaign?

They have replaced the pump?

I apologise as I thought I'd posted a response but it's not saved it.

The car went into a citroen dealer and they performed the recall and replaced the vacuum pump.

Since then the car has behaved impeccably. I suggested to the dealer that the car might sense it's not braking as it should and so slams on the eba to stop the car under braking. He couldn't agree either way but considered it a likely possibility. Either way...it doesnt do it post pump replacement.

Interesting. Glad it's fixed.

I have experienced the emergency brake assist once or twice. I nearly ate the steering wheel :lol: . What it does is boost the vacuum so that the pretty is very light but very strong on the brakes. The first time it happened (caused by very quickly pressing the brake pedal), I though I was going to stand the car up on the front two wheels. I guess that happens when you look away for a second in stop and go traffic.