|
|
|
|
|
#1
07-31-2006, 04:11 AM
|
|||
|
|||
ABS coming on - over sensitive!
Hi All
My 'other car' has a Bosch ABS system which is giving me a headache in resolving and so I would like to ask the experts here for some friendly advice. Hope you guys don't mind. Here's the background: Symptoms During relatively light braking (say approaching a T junction) the ABS engages as if one were on ice. The hydraulic 'pumping' and ABS sensation can be felt at the wheels. The road surface gives no reason for the ABS to engage. No ABS fault light No fault code stored Two of the toothed ABS sensors had become decoupled from the front drive shaft and was originally thought to be the cause, these were glued back in place but fault remains. Changed all pads to ensure brakes wern't 'sticking', wheels tested on a test station and brake pressures measure equal forces. Next thought I had was dropped counts from a sensor at slow speed (sensor's output voltage is proportional to speed), but by using diagnostic equipment which can measure each ABS sensor's count at the I/P to the ABS unit and compare with the other sensors, no count anomalies are shown! ie all counts are the same. I'm now at a loss as to what else could 'trick' the ABS unit into thinking the car's in a skid?? Any thoughts would be most welcomed. Lea
__________________
'93 R129 500SL-32 '89 190E 2.6 - sold in 2002 http://antron.pwp.blueyonder.co.uk/i...nature/Sig.jpg Last edited by LeaUK; 07-31-2006 at 04:36 AM. 
|
|
#2
08-01-2006, 03:07 AM
|
|||
|
|||
|
No thoughts?
Some additional info: The brake pedal also sinks after around 30 seconds of pressure (engine running, rock solid when engine off), very much like a leaky master cylinder so I replaced the MC and it still sinks. It also occasionally sinks then takes around 10 seconds to come back up. Strange. This may or may not be related. Question. When the ABS system is operating and releasing hydraulic pressure from a brake, where does the fluid go? Someone said to me it's dumped into the modulator which I'm guessing is some type of reserve space in the ABS unit itself!? Any thoughts most welcomed. Lea
__________________
'93 R129 500SL-32 '89 190E 2.6 - sold in 2002 http://antron.pwp.blueyonder.co.uk/i...nature/Sig.jpg Last edited by LeaUK; 08-01-2006 at 03:45 AM.
|
|
#3
08-04-2006, 09:42 AM
|
|||
|
|||
|
SOLVED
Even though the diagnostic equipment reported no sensor count errors new toothed rings on the front drive shafts (had to buy 2 new complete drive shafts as the rings are integral) solved the problem - weird! Lea
__________________
'93 R129 500SL-32 '89 190E 2.6 - sold in 2002 http://antron.pwp.blueyonder.co.uk/i...nature/Sig.jpg
|
|
#4
08-04-2006, 10:09 AM
|
|||
|
|||
|
hello LeaUK
I am happy you solved your problem so quickly. but I have one question. Weren't the rings just so dirty that sensors did not feel anymore each single tooth? thanks for reply.
__________________
Keep us posted especially if your problem is solved Present cars: My car: E-class 420CDI, 2008, W211, V8, 180 000km Wife's one: C-class 220CDI Sport Coupé, Euro, 2002, W203. 345 000km Son's one: GLK class 220CDI, 2009, W204 Sold E class 260E, W124, 1988 beloved car sold after 489 000 kilometres of reliable services (engine M103, clutch and 5 speed manual gear box all original). E-class, W210 320CDI, 2000[/B], 225 000km, Sold
|
|
#5
08-04-2006, 02:39 PM
|
|||
|
|||
|
All sensors and toothed rings were clean.
The fault didn't show on diagnostic equipment designed to count the pulses and compare wheels so I can only conclude that pulses were dropped (gained) intermittently due to the crack in two front rings. Myself, my repair garage the car Manufacturer's dealer and multiple brake and my car's manufacturer's specialists cannot understand the symptoms but the new drive shafts incorporating the new rings have certainly cured the issue! Thanks Lea
__________________
'93 R129 500SL-32 '89 190E 2.6 - sold in 2002 http://antron.pwp.blueyonder.co.uk/i...nature/Sig.jpg
|
|
#6
08-04-2006, 03:17 PM
|
|||
|
|||
|
<
..and where are these 'Driveshafts" on that car ?????????????
|
|
#7
08-08-2006, 04:15 PM
|
|||
|
|||
|
For info the car is a Peugeot 406.
The sensor rings are mounted on the front drive shafts adjacent the the CV joints. They are heat shrunk at manufacture and so complete new shafts were required (read expensive). Lea
__________________
'93 R129 500SL-32 '89 190E 2.6 - sold in 2002 http://antron.pwp.blueyonder.co.uk/i...nature/Sig.jpg
|
|
#8
08-08-2006, 04:30 PM
|
|||
|
|||
|
Quote:
You have two Benz models listed alomng with a Benz picture, so that surely does not indicate you were looking for info on Peugot. Thanks
|
|
#9
08-13-2006, 01:44 PM
|
|||
|
|||
|
Arthur
I take your point but it was intentional. There are three/four well known ABS system manufacturer's shared amonst vehicles and so the manufacturer of car is rather incidental. Also, had I mentioned the manufacturer I probably would have got 'what are you posting here for' comments so I wanted to avoid. I hope this thread will be useful for others whom experience the same phenomenon with their vehicles in the future. Cheers Lea
__________________
'93 R129 500SL-32 '89 190E 2.6 - sold in 2002 http://antron.pwp.blueyonder.co.uk/i...nature/Sig.jpg
|
|
#10
08-13-2006, 01:53 PM
|
|||
|
|||
|
<
Well, that sure does explain it ..................... Sorry for my confusion on the matter. I am just a Tech. Good Day.
|
 |
| Bookmarks |
|
|
Linear Mode
