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Discussion Starter #1
On the track last week, I had a major braking, ABS incident in the wet. Traction control was off. Straight after this incident, the ABS failure warning came up and it stopped working.

I unplugged the sensors under the bonnet, plugged them back in and it cleared the warning and all back to normal.

Now though, I have an issue it seems.... When on a fast road, doing around 60mph+ the little yellow traction control light flashes on and off (as when happens when loosing traction normally), but I am not losing any traction.

When I apply the brakes gently the pedal feel is like as though when the ABS is kicking in, but without the pulsing (it is a hard pedal feel). When I slow down, all back to normal and brake pedal feel is normal.

Any ideas from you brainy lot?
 

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I would assume the abs thinks a wheel is slipping either caused by a damaged sensor or perhaps it needs recalibrating? If you can do that that is. Can't say I ever fiddle with that unit but that would be my thought. Who knows if anything I've said is even right though :)
 

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:confused:

Well it cuts power when a wheel is slipping, so it is a form of traction control surely!? :confused:
Yes. In short, it reduces torque if both driven wheels are slipping (compared to rear wheels), and applies brake to a single wheel if one of the driven wheels is slipping ....
 

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I always took traction control as something that would control all 4 wheels. But I guess you could say its traction control for the front wheels only.

It really is nothing like VDC.
 

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I always took traction control as something that would control all 4 wheels. But I guess you could say its traction control for the front wheels only.

It really is nothing like VDC.
No, as the name already says, TRACTION control only applies to the driven wheels...
VDC is something competely different, and tries to keep the car heading the way you want it to by applying selective braking to all wheels, based on steering angle and yaw sensors ....
Both make use of the ABS system though ....

from elearn:
The antilock braking and anti-slip regulation systems (BOSCH 5.7 ABS with ASR) modulate brake pressure sent to the wheels to prevent loss of grip under all tyre and road surface conditions by cutting in automatically whenever one or both drive wheels begin to slip.
The ASR system increases vehicle stability and active safety by controlling drive wheel slip. If slip is caused by excessive power transmission, it cuts in to reduce engine power through communication with the engine management control unit. if slip is detected at a single wheel, the system cuts in to brake the slipping wheel by acting on the modulation solenoid.
ASR comes on automatically whenever the engine is started. The system can be deactivated by operating a button on the central console. When the system is off, an LED on the button comes on at the same time as a warning light on the control panel (speedometer module).
The warning light flashes when the system cuts in to notifiy the driver that the ASR system has cut in due to road surface grip conditions.
The warning light comes in in fixed mode when the control unit detects an error in the ASR function.

However, we're moving away from the original question :D

Perhaps the abs system needs time to recalibrate after your problem on the track...
The same is known to happen if you f.i. have 2 wheels with dissimilar circumference/tires, like a spacesaver.... If you forget to switch off the ASR in that case, it screws up the ASR as the ecu sees impossible inputs, and requires driving a number of miles afterwards with asr switched off to recalibrate the system....
 

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Discussion Starter #9 (Edited)
I did have to drive on the space saver for about 50 miles, but it was on the rear. But I did have a fairly new tyre on one front side and a completely bald tyre on the other side - I wonder if the difference in size was enough to upset it....... I'll give it some time and see if it sorts itself out........thanks for your help. Much appreciated.
 

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Discussion Starter #11
I still have this problem. When I get to 80mph the yellow traction control light flashes on the binnacle, then when I drop back down to under 80mph it stops flashing.

I had an ABS fault, and found a broken wire on the speed sensor on the front right, which I repaired, which has cleared the ABS failure fault I had previously and now under 80mph everything works fine.

No faults are stored or reported now.

Is there anything else that could be causing it? Bit confusing....!
 

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What does it do if you turn the ASR off first? Does it still flash?
 

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What software are u using?
 

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Discussion Starter #14
What does it do if you turn the ASR off first? Does it still flash?
No it doesn't flash when I turn it off. So I drive everywhere with it turned off. But would be good to get fixed.

Using registered version of multiecuscan with correct cables.
 

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I must register mine. What values are the giving when driving. Can you data log it
 

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Discussion Starter #16
I must register mine. What values are the giving when driving. Can you data log it
Hmm that's a bit over my head....what values should I be looking at?!
 

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Well first you need to connect up to the abs module. One of the tabs accross the top gives a page of all the sensor connected to the abs unit. Think its the 3rd tab. If you tick the box next to each sensor it'll show the values the abs unit is working it out to be in KM. Now somewhere is a record data option. Can't remember 100% as I've bever had to use it so only played a couple of times. Looking at images on FES webpage it's the last tab. That is as much as I can help. :)
 

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I would drive in a straight line and log wheel speed on all 4 wheels, they should all be the same.

Was this problem apparent before you just fixed the broken wire?
 

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Discussion Starter #19
I'll give that a go. If one wheel is significantly different speed to the others is that the speed sensor at fault? Odd it only occurs at 80+?


Yes this started happening just after a track day. Ignored it for months, then recently had the ABS fault and fault reader identified the front right speed sensor, and then I fixed the broken wire and cleared the fault and all good. Not sure if they are related or not. I suspect not.
 

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I'll give that a go. If one wheel is significantly different speed to the others is that the speed sensor at fault? Odd it only occurs at 80+?


Yes this started happening just after a track day. Ignored it for months, then recently had the ABS fault and fault reader identified the front right speed sensor, and then I fixed the broken wire and cleared the fault and all good. Not sure if they are related or not. I suspect not.
It could be that the ring gear that the sensor reads (its part of the wheel bearing) is corroded, and it struggles to pick up a clean signal, or there is something wrong with the sensor tip. Did you go in a gravel trap at the trackday? I had a crank sensor do this to me once on a Fiat, its essentially the same theory with a magnetic sensor reading a toothed wheel; it read OK upto thereabouts 3,000 - 3,500rpm depending on temperature and then after that the signal was too weak to create peaks & troughs clean enough for the ECU to read, so I got constant misfires until the revs dropped.
 
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