Welcome to 911UK
The only place for Porsche, 911uk is the definitive enthusiast and resource site for the Porsche 911.
Registration is fast, simple and absolutely free, so join up today for full access to the site and benefit from latest member offers.

Porsche Classifieds
Sell Your Porsche on 911uk
Create a Free Classified Advert
Search Ads
Classified Adverts FAQ
Trade Classified Information
Buyer & Seller Fraud Protection
Consumer Rights Act
Pre Purchase Inspection (PPI)
Porsche Car Sourcing
Porsche Cars Wanted
Official Porsche Centre Reviews
Model
Stock
Porsche 911
991 : 2011- 17
997 : 2004- 65
996 : 1997-2005 31
993 : 1993-1998 3
964 : 1989-1993 6
Carrera 3.2 : 1983-1989 2
Carrera SC : 1977-1983 2
930 Turbo : 1975-1989 0
Early 911 : 1964-1977 3
Porsche Other Models
Classic : 1950-1965 0
Boxster : 1997- 18
Cayman : 2005- 12
Cayenne : 2003- 3
Macan : 2014- 1
Panamera : 2009- 0
912-914-924-928-944-968 1
959 - CarreraGT - RaceCar 1
Car Parts For Sale & Wanted
Other Items For Sale & Wanted
Wheels Tyres For Sale & Wanted
Number Plates For Sale Wanted

Porsche Services
Porsche Body Shop Repair
Paint Protection & Wrapping
Porsche Classic Insurance
Porsche Classic Parts
Porsche Classic Restoration
Porsche Design Collection
Porsche Engine Gearbox Rebuild
Porsche Heritage & History
Porsche News
Porsche Picture Gallery
Win a New Porsche 911

Porsche Parts
Body Parts, Body Styling
Brakes, Clearance
Electrical, Exhausts
Engine Cooling, Engine Electrical
Engine Rebuild, Heating Cooling
Interior Incar, Lighting
Rubber Seals, Service Parts
Steering, Suspension
Transmission, Workshop Tools
Early 911, 911 - 930, 928 - 968
964 - 993, 996 - 997, Boxster
Cayman, Cayenne, Panamera

Porsche Model Range
911 [991] 2011-Current
Porsche 911 [991]
911 [997] 2004-Current
Porsche 911 [997]
911 [GT] GT1-GT2-GT3
Porsche 911 [GT]
911 [996] 1997-2005
Porsche 911 [996]
911 [993] 1993-1998
Porsche 911 [993]
911 [RS] RS-RSR
Porsche 911 [RS]
911 [964] 1989-1993
Porsche 911 [964]
911 3.2 1983-1989
Porsche 911 3.2 Carrera
911 SC 1977-1983
Porsche 911 SC
911 [Early] 1964-1977
Porsche 911 [Early]
Boxster & Cayman
Porsche Boxster & Cayman
Cayenne & Panamera
Porsche Cayenne & Panamera

911uk Site Partners

Post new topic   Reply to topic
Author Message
Rickyhull
Monza


Joined: 06 Mar 2016
Posts: 205



PostPosted: Sat Jan 19, 2019 6:42 pm    Post subject: Abs pulsing only at low speed 2mph-10mph Reply with quote

Evening all!, basically have this issue with my 996 c4 1999 3.4 where as at low speed the abs pulses, bought it like this so no idea when it started nothing wrong with the brakes as such all tyres pretty good and matching and all tyre pressures correct, no warning lights or faults but this happends, has anyone successfully fixed this as upon a google search it seems a few people get this from time to time but nobody ever updates there threads as to how they’ve resolved it so it would be great to hear people’s solutions that have resolved them on here
Thanks ricky
 
  
View user's profile Send private message
   
deMort
Long Beach


Joined: 21 Mar 2015
Posts: 6155
Location: Brighton


PostPosted: Sat Jan 19, 2019 7:05 pm    Post subject: Reply with quote

It will more than likely be a wheel speed sensor thats getting old , low speed and the signal is not strong enough so the car thinks the wheel has locked up .. hence abs kicking in .

To find which one .. a fault code read out and hopefully there will be a code ..

If not then its a case of scopeing each sensor and looking for the one with the weakest signal.

You could try an ohms check on each sensor as well , youll be looking for the one thats different from the others but this is a bit of a hit an miss check.

Seperate note for any Cayenne owners .. never use an Ohm meter on these sensors .. it kills them .
_________________
.

My Daughter's Crowdfunding page Here

Mechanic

7pm - 9pm

Now At An Indy.
 
  
View user's profile Send private message
   
Rickyhull
Monza


Joined: 06 Mar 2016
Posts: 205



PostPosted: Sat Jan 19, 2019 7:10 pm    Post subject: . Reply with quote

Great advice thank you!, I was thinking along that same path either speed sensor or the ring bit inside that the speed sensor uses, doesn’t seem to be any fault codes so I’ll try and test them see what there all reading and will update you guys either way, have you had this problem before on yours?, I guess there’s not much else it could be since there’s no warning lights etc and no other braking issues other than this at low speeds
 
  
View user's profile Send private message
   
deMort
Long Beach


Joined: 21 Mar 2015
Posts: 6155
Location: Brighton


PostPosted: Sat Jan 19, 2019 7:18 pm    Post subject: Reply with quote

I think the ring whilst posible might tend to give you problems at higher speeds .. have a look at each one though , your looking to see if they are heavily corroded ... and i mean VERY heavily corroded .

Off hand i would start with looking at the sensors .. some testers give you a value as the car moves so you would see x3 wheels at 5 mph and x1 at 0 if it is a sensor or a ring .


Ive not had it before on mine .. i dont actually own a Porsche im afraid .. im a Porsche Mechanic Very Happy
_________________
.

My Daughter's Crowdfunding page Here

Mechanic

7pm - 9pm

Now At An Indy.
 
  
View user's profile Send private message
   
Rickyhull
Monza


Joined: 06 Mar 2016
Posts: 205



PostPosted: Sat Jan 19, 2019 7:34 pm    Post subject: Reply with quote

Agh I see I’m not sure if my friends diagnostics shows up individual wheel speeds x4 but I’ll look into it as that would be a much easier way to pin point the problematic corner for sure
 
  
View user's profile Send private message
   
deMort
Long Beach


Joined: 21 Mar 2015
Posts: 6155
Location: Brighton


PostPosted: Sat Jan 19, 2019 8:54 pm    Post subject: Reply with quote

Just for us nerds here ..

The sensor is a magnet with copper windings.

When you pass a soft iron metal over this it will generate a small voltage .. emf i belive (Electro Motive Force ).

The sensor will have a metal part then a gap then a metal part going in front of it .. this will in turn generate a voltage then no voltage then a voltage in the sensor .. an oscilateing signal basically .

The car sees this as a waveform and knows the rotation speed of the wheel due to the frequency of said wave form.

If something interupts this signal be it a poor / corroded ring the pattern will alter to a flat point at times , low speed and this is far more likely due to corroded highs and lows of the rings , corrosion will almost join two high points of the ring together .. or a poor sensor that cant generate a descent signal .

If you have a fast enough scope then you will see a square wave .. the reality is most scopes show an analog signal or a slope up / down .
_________________
.

My Daughter's Crowdfunding page Here

Mechanic

7pm - 9pm

Now At An Indy.
 



797360chartjpg_00000036172.jpg
 Description:
 Filesize:  55.53 KB
 Viewed:  2059 Time(s)

797360chartjpg_00000036172.jpg


  
View user's profile Send private message
   
Rickyhull
Monza


Joined: 06 Mar 2016
Posts: 205



PostPosted: Sat Jan 19, 2019 9:57 pm    Post subject: . Reply with quote

Thanks for that it’s quite an interesting little read I’m looking forward to getting started on it now and getting to the bottom of it now!, I’ll have it plugged in tomorrow see exactly what info we can extract from the diagnostics before I start stripping and inspecting the rings etc. Thanks for your help!
 
  
View user's profile Send private message
   
HSC911
Long Beach


Joined: 23 Jul 2014
Posts: 6286
Location: Bedford


PostPosted: Sat Jan 19, 2019 11:18 pm    Post subject: Reply with quote

Don't forget to donate too Grin

Thumb
 
  
View user's profile Send private message
   
Griffter
Spa-Francorchamps


Joined: 22 May 2016
Posts: 270



PostPosted: Sun Jan 20, 2019 7:47 am    Post subject: Reply with quote

I had exactly this on my wife’s rover years ago. It was a cracked reluctor (ABS) ring. My moneys on a senor or ring.
 
  
View user's profile Send private message
   
Rickyhull
Monza


Joined: 06 Mar 2016
Posts: 205



PostPosted: Sun Jan 20, 2019 3:03 pm    Post subject: Reply with quote

Yea I agree one or the other, don’t think will get chance to have it plugged in wile next weekend now but will certainly update you guys in the hope that it helps somone else too, can the abs ring bit be changed if it is that or is that part of the drive shaft of these?
 
  
View user's profile Send private message
   
wasz
Sepang


Joined: 28 Dec 2012
Posts: 2864


1999 Porsche 996 Carrera 2

PostPosted: Sun Jan 20, 2019 8:22 pm    Post subject: Reply with quote

I think they are in the seal of the wheel bearing
_________________
My special order MY99 Vesuvious Charcoal 996 | Clutch, Fly RMS IMS AOS Job |
Steering Rack Hard Lines | Air Con Compressor / System
 
  
View user's profile Send private message
   
deMort
Long Beach


Joined: 21 Mar 2015
Posts: 6155
Location: Brighton


PostPosted: Sun Jan 20, 2019 8:47 pm    Post subject: Reply with quote

Im afraid the ring is part of the driveshaft .. you are looking for x2 ring high spots almost joined together .. you can scrape out the rust between the two .. that is if thats the fault .

Figure out which corner of the car is the problem first then go from there .
_________________
.

My Daughter's Crowdfunding page Here

Mechanic

7pm - 9pm

Now At An Indy.
 
  
View user's profile Send private message
   
Rickyhull
Monza


Joined: 06 Mar 2016
Posts: 205



PostPosted: Mon Jan 21, 2019 8:48 pm    Post subject: Reply with quote

Little bit of an update plugged it in today no faults stored, tried to get the values of all 4 speed sensors on durametric diagnostics and annoyingly I can’t seem to get it to show anything it doesn’t do anything, will check it out on my friends diagnostics at weekend
 
  
View user's profile Send private message
   
Rickyhull
Monza


Joined: 06 Mar 2016
Posts: 205



PostPosted: Sun Jan 27, 2019 4:11 pm    Post subject: Reply with quote

Bit of an update done a diagnostics and no faults, done a scan of the abs sensors and nothing flagging up as out of ordinary so guess it must be the abs ring either damaged or rusty/corroded
 
  
View user's profile Send private message
   
JS1500
Monza


Joined: 12 Apr 2017
Posts: 201
Location: Aberdeen


PostPosted: Sun Jan 27, 2019 9:39 pm    Post subject: Reply with quote

I had this fault on my C4 and found a garage that could replace the reluctor rings without having to replace the driveshaft.
I actually have a couple of spare rings, as I bought four. If they're the same as the ones you need you can have them for the cost of postage...
_________________
2000 996 C4 - Guards Red
 
  
View user's profile Send private message
   
Rickyhull
Monza


Joined: 06 Mar 2016
Posts: 205



PostPosted: Sun Jan 27, 2019 9:56 pm    Post subject: Reply with quote

Great thanks that’s the best thing that I’ve heard as it does seem very plausible that being the fault but then I’ve not heard of anyone else having issues with the rings so worried I’m heading in the wrong direction, was your symptoms the same as in abs pulsing but only at very low speed?
 
  
View user's profile Send private message
   
wasz
Sepang


Joined: 28 Dec 2012
Posts: 2864


1999 Porsche 996 Carrera 2

PostPosted: Mon Jan 28, 2019 11:04 am    Post subject: Reply with quote

Rickyhull wrote:
Bit of an update done a diagnostics and no faults, done a scan of the abs sensors and nothing flagging up as out of ordinary so guess it must be the abs ring either damaged or rusty/corroded


Can this diagnostic log all 4 wheel speeds?

Then drive the car in a straight line and see which one is out compared to the others.

Then you can start to look for them.

When I fitted new front wheel bearings to my C2 Im sure the wheel bearing seal had something written on it to say it has the reluctor in. But yours being a C4 will be as DeMort says on the driveshafts.
_________________
My special order MY99 Vesuvious Charcoal 996 | Clutch, Fly RMS IMS AOS Job |
Steering Rack Hard Lines | Air Con Compressor / System
 
  
View user's profile Send private message
   
Rickyhull
Monza


Joined: 06 Mar 2016
Posts: 205



PostPosted: Mon Jan 28, 2019 12:30 pm    Post subject: Reply with quote

Unfortunately not on my friends although I have got durametric and it does show up all 4 wheel speed sensors but doesn’t give off speeds/voltages so maybe because it’s the free version I’m not sure 👎
 
  
View user's profile Send private message
   
Rickyhull
Monza


Joined: 06 Mar 2016
Posts: 205



PostPosted: Fri Feb 22, 2019 2:10 pm    Post subject: Update Reply with quote

Bit of an update checked abs rings and all seem ok, not sure what the next best thing to do is, does anyone hav a link to a free download fault code reader so I can read live data to see which wheel seems to be reading differently to the rest? I’ve got a durametric cable and program free one off the internet but can’t seem to get it to do anything on the live data for wheel speeds
 
  
View user's profile Send private message
   
easttorks964cab
Monza


Joined: 02 Jun 2008
Posts: 151
Location: East Yorks


PostPosted: Sat Feb 23, 2019 6:29 am    Post subject: Reply with quote

Ricky (OP), if it helps, I agree with demort on the wheel speed sensor. As daft as it may sound on a 911 site, one of my work vans had the same problem and it was the sensor....same symptoms and the same diagnosis as demort suggests. if its not the sensor, then its probs the bearing (as the two work in tandem). I hope this helps.
 
  
View user's profile Send private message
   
Display posts from previous:   
Post new topic   Reply to topic   All times are GMT - 12 Hours
Goto page 1, 2  Next
Page 1 of 2

 
Jump to:  

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You can attach files in this forum
You can download files in this forum
You cannot post calendar events in this forum