Brake light + VDC OFF + SLIP
 

Hello,

Need some major help here. I am not financially in a position where I can just take my car to get it diagnosed and pay big bucks so you guys would be helping me tremendously.

I recently took my car to get my tires replaced. Sometime after and this could be entirely unrelated I've noticed a few things.

First I noticed that under acceleration my brake light comes on however obviously the emergency brake is not on.

Second is after driving for a bit the VDC off light and slip light comes on and stays on.

I am very confused as to what are causing both. I read somewhere someone said to fill the brake fluid to the max and this should fix one of those problems, can't remember which one. I have yet to try that but find that hard to believe it will resolve it.

Has anyone had this or can point me in the right direction? I truly appreciate it!

Thanks,

Mike

There's a 99.9% chance it's low brake fluid, at least for the first problem. Whether you find it hard to believe or not, it has solved your exact problem for probably hundreds of Z owners here.

The second problem could be caused by the tires not being close enough in size front to rear. It's picky about overall height, and will freak out if it's more than a 3% or so difference.

OK awesome and damn I did change the front size from the rear. So I will not be able to resolve this or maybe an ECU clear? Any thoughts? I also wonder if it's showing the VDC is off and it's actually on.

It's the low fluid level causing both, I know from experience, when the fluid gets low the traction control shuts off which is why the light is on.

Maybe. The tires may be confusing the ecu as well. And no, there's nothing you can do to fix that particular problem other than buying the correct size tires. Try the brake fluid first since it's the cheapest fix. If the problem persists, you need the correct size tires.

FWIW, I've seen all three lights on in various combinations (all on, two on, one on). Topping off the brake fluid reservoir to the max line fixed it each time.

If that doesn't do it, follow Chuck's advice and check your tires. What size tires did you get?

I just bought them and was recommended by jchammond a member here. I doubt it's the tires because for the longest time while they were on I don't believe it was doing this.

I went with: 245-40/19
285-35/19

Will fill Brake fluid after work and report back here. Seriously love you guys.

Those tire sizes should not give you any problems. JC knows his stuff.

245*.4 =98
285*.35=99.75

Within the 3% tolerance.

Go grab a bottle of motul rbf 600 and top up the brake. Check your clutch fluid and top up if needed too. Toss the bottle after since brake fluid is very high water absorption

I used Dot 3 hopefully that is ok. From my 15 minute drive looks like it resolved all my issues! Super happy, thanks again guys. Much appreciated!

how are your brakes? the brake light may be a warning your brakes need attention.

I find your lack of faith disturbing.

I think this goes without saying... we always try to help. But we cannot help stupid:ughdance:

Generally, there are two reasons these lights come to warn you the brake fluid is low. One is brake pads wearing over time. The other is boiling the brake fluid.

If you aren't too hard on your brakes, then it might just be the pads are wearing down. The pads get thinner as they wear, allowing more fluid into the caliper, which lowers the reservoir level gradually over time.

If you boiled the fluid, be prepared for the same thing to happen again using Dot 3 brake fluid :twocents:

It is pretty easy to boil most brake fluids on this car. The boiled fluid is thinner and often leaks out of the bleeder valve (ruining your nice sports calipers :eek:), thus lowering the reservoir level causing the lights to come on like you just experienced.

Dot 4 has a higher boiling point than Dot 3. And Dot 5.1 has a higher boiling point than Dot 4. Brake fluid is not expensive. If I were you, I would change out the fluid with Dot 4 or Dot 5.1 (DO NOT USE silicone-based Dot 5). Motul RBF600 is highly recommend if you brake hard at all.

It is always better to understand why the problem is occurring so you can address is properly. Sure you can just continue to fill the reservoir with brake fluid every time the lights come on, but that doesn't really solve the underlying problem. New brake pads might be in order or or you might want a higher temp fluid that is less prone to boiling. With this approach you are much more likely to prevent the problem from recurring (at least for a long time).

Could this be a wheel speed sensor issue?