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ABS test procedures and equipment

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Posted 5/15/2007 4:22 PM

NorthseaRoughneck
Extreme Veteran

Date registered: May 2006
Location: Berghem, the Netherlands
Vehicle(s): 300GD SWB - 300GD LWB
Posts: 538
500

ABS test procedures and equipment

Hello all,

I am (still) trying to work out my mysterious ABS problem(s) and I have some random questions.

The story so far:

My ABS light stays on all the time as soon as the ignition is turned on. I have completed some tests according a trouble shooting sheet which was kindly sent to me by 'EuroTruck' with some result. According the sheet there is nothing wrong with my locker switches nor with my ABS switch.

Because the light stays on all the time I ass-u-me that there is nothing wrong with the sensors because as far as I know when a sensor is f#cked it would make the light come on only after exceeding a speed of +/- 5 KM's per hour. I have checked the relays (both engine and valve) on the ABS pump and they seem to be OK. Also checked the over voltage surpressor fuse which is OK too.

I have been to several MB dealers in my neighborhood but so far without result. Their story is that they can not give me any indication on how long it will approximately take to have the entire system checked and tested according the manual. All they can tell me is that it will cost me somewhere close to €90,- excluding tax (VAT) per hour to have a mechanic working on it. They tell me that it will cost THEM too much money if they start to look for the problem

After going through the entire ABS section of the official manual (thanks '4x4abc' for making that available) I now know which tests need to be done to check the entire ABS system except the ABS control unit. In order to complete these 35 tests apparently one needs three pieces of equipment being 1) a ABS valve control unit (W667 589 02 21 00 - €105,- excl.) 2) a socket box (W124 589 00 21 00 - €135,- excl.) and 3) a connecting cable (W129 589 00 63 00 - €145,- excl.). Obviously a multi meter is necessary as well.

Question 1: Anybody have any clue on my ABS problem in general?

Question 2: Anybody experienced something similar and could give me some feedback on testing and/or solutions?

Question 3: Anybody ever worked with any of the above mentioned equipment and/or home fabricated some test setup similar to the above equipment?

Question 4: By change, anybody here who has this equipment on the shelf (willing to lend it out) so I could have a go myself?

To be honest, I don't trust any mechanical workshop anymore as I have been ripped off a couple of times (including official MB dealer) so I would like to solve this one myself. Oh well, maybe I will end up buying the 3 pieces of equipment and finally solve the ABS mystery.

Help!

Anybody?

Regards,

NorthseaRoughneck

Edited by NorthseaRoughneck 5/15/2007 4:23 PM

#74460

Author

Posted 5/16/2007 1:12 PM

G-AMG
G-Class DIY Host

Date registered: May 2006
Location: South Texas
Vehicle(s): '04 G55, '80 280GE, '99 S420, '98 E320, 2011 E350
1000

RE: ABS test procedures and equipment

NSR,

I don't know if there is any comonality between models, but I had a similar problem with the S420, and apparently it is a common failure: Brake Pedal Switch

10 euros, and 10 min to replace. It might be a cheap "first try".

#74590 - in reply to #74460

Author

Posted 5/16/2007 1:39 PM

AlanMcR
Expert

Date registered: Apr 2006
Location: US, CA, Los Altos
Vehicle(s): G300DT E300DT 230SL
Posts: 3500
2000

RE: ABS test procedures and equipment

There should be a way to pull the codes on any ABS system. It will happily tell you what it thinks is wrong. You could test the difflock/ABS disable signal by finding the back of the switch and verifying that the line goes high when the switch isn't thrown. As I recall the line is pulled high (>5v) by the ABS computer and shorted to ground by the switch.

#74595 - in reply to #74460

Author

Posted 5/16/2007 5:04 PM

G350DT

Date registered: Dec 1899
Location:
Vehicle(s):

Re: ABS test procedures and equipment

My ABS light will not go out either.
Thanks going to check the break switch. If not
I say go for the ole black tape over the light trick
May be what I have to do

#74627 - in reply to #74460

Author

Posted 5/16/2007 5:07 PM

AlanMcR
Expert

Date registered: Apr 2006
Location: US, CA, Los Altos
Vehicle(s): G300DT E300DT 230SL
Posts: 3500
2000

Re: ABS test procedures and equipment

G350DT - 5/16/2007 2:04 PM

My ABS light will not go out either.
Thanks going to check the break switch. If not
I say go for the ole black tape over the light trick
May be what I have to do

Check to see if you have a mechanical brake force distributor attached to the rear differential. If not, then the ABS computer is doing this function for you. Without properly distributed braking force you are begging for a spinout.

#74628 - in reply to #74627

Author

Posted 5/17/2007 8:50 PM

ewalberg
Expert

Date registered: Apr 2006
Location: Past: San Francisco. Present: Germany
Vehicle(s): 2000 g500
Posts: 1887
1000

Re: ABS test procedures and equipment

I broke my sensor when doing my wheel bearings (the little bugger didn't want to come out of it's hole) and i thought it registered a problem as soon as i turned on the car?... not totally sure though...

#74793 - in reply to #74460

Author

Posted 5/18/2007 8:32 AM

NorthseaRoughneck
Extreme Veteran

Date registered: May 2006
Location: Berghem, the Netherlands
Vehicle(s): 300GD SWB - 300GD LWB
Posts: 538
500

RE: ABS test procedures and equipment

Thanks guys for your input!

As it seems I am standing pretty much alone in this one. I will check out another two options (two shops/mechanics) before going for my last option which will be purchasing the required tools and go on an ABS quest myself.

AlanMcR, I have spoken to several people (including MB mechanics) about the possibilities of pulling codes from the ABS system. Some say it is possible some say it is not and then you have the ones who say that it depends on what kind of ABS system we're talking about and on top of that you have the ones who openly admit that they haven't got the slightest clue.

I would very much like to get the story right. Is it ... or is it not possible to check the ABS system by hooking up a device to a plug/connector? As per my profile I drive a 1990 300GD (VIN WDB46332717071385). Please guys ask yourselves, ask your trusted mechanics, ask your wives, your mistresses, your girlfriends ... I don't care who. Go through all your books, your manuals, your favorite sites (not the porn ones) your epc's, your WIS's but please answer my question. More importantly, answer it in complete agreement with each other.

According the 461, 463 Brake Service Manual my 300GD should be equipped with a four-channel system. After reading the ABS section over and over again I have come up with a couple of possibilities for why the ABS indicator light stays ON after starting the engine;

1) There's an under voltage in the vehicle on-board electrical system
2) The power supply to the electronic control unit could be interrupted
3) The control unit of a 3-channel system is installed in a 4-channel system

Q1) How do I check if the voltage in the on-board electrical system is sufficient?
Q2) How do I check the power supply to the electronic control unit?
Q3) Anybody who can tell me how I can check (part number??) whether I have a 3-channel or a 4-channel control unit installed?

Obviously if all else fails, I will have to go through the 35 different tests to figure out what the heck is wrong with my ABS system. No matter what, I will solve this problem ... or better yet ... challenge and ones I do I will report back.

See the trouble is though, that I have to put my 300GD through the roadworthy test every year and ABS is a pass/fail item. I could, like last year, disconnect the ABS indicator light (and hope that they don't find out) but that still doesn't solve the problem of not having a working ABS system on board. Safety you know!

Oh well, if it is possible to solve this ABS issue I'll solve it straight away. If it is impossible ... it will take a little while longer!

Answers, tips or help in any other way are more than welcome!

Thanks and regards,

NorthseaRoughneck

#74858 - in reply to #74460

Author

Posted 5/18/2007 4:32 PM

EuroTruck
Extreme Veteran

Date registered: Apr 2006
Location: Oakwood, Georgia - USA
Vehicle(s): 2012 Audi A4 Avant S-Line, 2015 Ridley NOAH SL
Posts: 518
500

RE: ABS test procedures and equipment

Hi Rick,

I just emailed a 24 page .pdf file to you that outlines how to diagnose ABS problems on the ABS electrical side of things.

Hope this helps,

-Sean Philyaw

#74891 - in reply to #74460

Author

Posted 5/18/2007 5:20 PM

DUTCH
Administrator Doppelgänger

Date registered: Apr 2006
Location: US, GA, Atlanta
Vehicle(s): 2015 Audi Q7 3.0 TDI,2018 Sprinter
Posts: 9963
5000

RE: ABS test procedures and equipment

EuroTruck - 5/18/2007 4:32 PM

Hi Rick,

I just emailed a 24 page .pdf file to you that outlines how to diagnose ABS problems on the ABS electrical side of things.

Hope this helps,

-Sean Philyaw

Why not post it here so we all can benefit?

#74894 - in reply to #74891

Author

Posted 5/18/2007 5:53 PM

EuroTruck
Extreme Veteran

Date registered: Apr 2006
Location: Oakwood, Georgia - USA
Vehicle(s): 2012 Audi A4 Avant S-Line, 2015 Ridley NOAH SL
Posts: 518
500

RE: ABS test procedures and equipment

DUTCH - 5/18/2007 5:20 PM

EuroTruck - 5/18/2007 4:32 PM

Why not post it here so we all can benefit?

I wasn't sure if that would be copasetic due to bandwidth, etc.

Edit: Just tried to attach the file and it is too large.

-SP

Edited by EuroTruck 5/18/2007 5:57 PM

#74899 - in reply to #74894

Author

Posted 5/18/2007 7:46 PM

4x4abc

Date registered: Apr 2006
Location: La Paz, Baja California, Mexico
Vehicle(s): 02 G500
5000

Re: ABS test procedures and equipment

Sean,

a link would do

#74907 - in reply to #74460

Author

Posted 5/19/2007 4:54 AM

NorthseaRoughneck
Extreme Veteran

Date registered: May 2006
Location: Berghem, the Netherlands
Vehicle(s): 300GD SWB - 300GD LWB
Posts: 538
500

RE: ABS test procedures and equipment

Sean,

Ones again thanks for trying to help me out with this one. Funny how a guy in the US dealing with G's is willing to help me out as where the Dutch dealers are not even trying to.

The tests outlined in your PDF file (from WIS I suppose?) are the same ones as I have come across in the Brake Service Manual - ABS section. Minus of course the handwritten comments

Thanks anyway, at least I know that there is somebody out there who is trying to help.

So, I take it then that there is no other way than those tests to check my ABS system?!

Attached is a picture of an 8 plug connector type thingy which was pointed out to me, by one of the people I have spoken to, as a connector to hook up to a device which would read the ABS system codes. The numbers 1, 2 and 4 actually have copper lining and seem to look like wired up. All the others are empty. Anybody any clue on whether this guy was right or wrong?

If he was right then what kind of device am I looking at to hook up to? I am pretty sure it won't be a (regular) computer as would most likely be the case with modern day cars. If he was wrong, then what the heck is this connector for?

Back to the 35 tests once more. Anybody here who has done these checks at some point who could give me a time span indication? This so that I can make a decision about buying the equipment myself or have them done by a dealer/mechanic. You know, which of the two options would work out to be the most cost effective.

Thanks once again ... regards,

Rick

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#74940 - in reply to #74891

Author

Posted 5/19/2007 5:32 AM

NorthseaRoughneck
Extreme Veteran

Date registered: May 2006
Location: Berghem, the Netherlands
Vehicle(s): 300GD SWB - 300GD LWB
Posts: 538
500

Re: ABS test procedures and equipment

Harald,

The tests described in the PDF file Sean has send me are the same tests as described in the 'Brake Service Manual - ABS section' that I have found on the '461/463 Ultimate Workshop' DVD.

A link to that DVD would have been a nice option

As said before in one of my posts above, thanks for making that information available. So far it has helped me a lot and I am sure it will help me out in the future.

Regards,

Rick

#74943 - in reply to #74907

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