pzull

Was on track last wkend and ABS light kept coming on at sharp right hairpin. Brakes seem to work, ABS seems to work though I dont use it much (usually brake till just before ABS comes on)

No ABS light on hard braking just on sharp right turns. Left turns no issue.

What's up?

BTW, most dreaded fear cam true this trackday, boost came on suddenly on turn exit and spun me out, happened so fast couldnt catch it

B R

Did you check fluid level?

Staffan

Therer are 3 break related lights (or 4 with the parking break).
Just to make sure, this is the ligth that says "ABS" in the middle?

If it's the ABS light, does your speedo show any speed when the light is on?

pzull

Brake fluid level OK.
Light is the one with ABS in the middle
Have to test again to see if speedo shows any speed when light comes on. What if it does or does not? What else could be wrong?
Car still runs great but my fear is coming down a long straight and suddenly finding i have no brakes. Right now it brakes just fine

kulismilan

I guess I know what Staffan thinks. Speedo is linked to front ABS sensors. If you have no connection between them or sensor is getting loose somehow (?) during the cornering your ABS light comes on and speedo does not work. Speedo cut-off can happen for very short period of time. This does not have any impact on brakes functionality except ABS system itself. Check the sensors and round white plugs for connection.

Staffan

If the speedo goes down to 0 I would think you have a problem with the ABS relay or perhaps the left speed sensor.

When the light goes on, does it stay on until you shutdown the engine, does it flicker or does it stay on for a "while" after the turn? Have you had a chance to break while the ligth is on (see below)?
Not sure the ABS light allways means "ABS disabled".

If you want to know how you car breaks without ABS, just unplug the ABS relay.
You will have very little rear breaking (for safety reasons) and unless you have an even weight-distribution over the front wheels, one of them will lock-up very easily. Since the break balance is very heavy towards the front (without ABS), you will lose alot of breaking force, so you want to get rid of this problem.

The obvious things to check is the connection at your speed sensors, borrow a ABS relay from a friend, "wiggle" the wires and contact on the ABS box etc. since the problem is coming and going.

Have you posted about this on the 964 forum?
If not, probably a good idea.

pzull

THe light and buzzer comes on only on the sharpturn and goes away a few seconds after the turn. Have not tried braking when light comes on as it does so on hard mid cornering and taking corner slow does not trigger the light.

Will do the checks you mentioned. Thanks guys

Staffan

Okey.
This is an interesting problem.
Somone should be able to tell which types ABS faults that triggers the buzzer, should be some documentation somewhere.

You get the feeling that something is moving under extreme conditions.
Not sure it's the "righ thing to do", but perhaps you could try starting the engine, having someone in the car and:
- disconnect the ABS relay (buzzer or no buzzer), again not sure if this is "good"
- wiggle the speed sensor contacts
- wiggle everything related to the ABS system

I did some reading in Adrians book last night, one thing that disables the ABS is if the voltage gets to low, thinking that the battery might tilt and the + contact has a temporary short on the body or something...worth checking at least