Removing abs from 85 sd - PeachParts Mercedes-Benz Forum

t walgamuth · #1 08-16-2010, 06:55 PM

I just searched but did not find any threads pertaining....

The 85 300sd I recently acquired seems to have its abs system disabled. If that is so I am wondering if I can remove the unit in its entirety?

I am averse to lugging around dead weight.

compu_85 · #2 08-16-2010, 06:56 PM

Why not fix it instead and enjoy shorter, more stable stops on most surfaces? The system is fairly simple and spares can be hand from most other Mercedes in the boneyard.

-Jason

t walgamuth · #3 08-16-2010, 07:07 PM

How do I know what is wrong with it?

compu_85 · #4 08-16-2010, 07:19 PM

You said the system is disabled. How did you come to that conclusion? Does the light in the cluster come on?

There are 3 sensors, the computer, the valve / pump unit, and some wires connecting them. By 85 I think the computer was smart enough to give you blink codes, I'd have to read the repair manual. Checking the sensors should be fairly easy, just unplug the connector from the computer and use a meter to check the resistance.

The whole system is very light. I'd guess that all of it together weighs under 15 lbs.

-J

t walgamuth · #5 08-16-2010, 07:47 PM

I was told it is disabled by the previous owner.

Renntag · #6 08-16-2010, 07:52 PM

I am not a fan of most ABS or Stability control systems, as in many cases braking distances are increased and certain evasive maneuvers are more difficult.

I would say, pull the system out and sell the parts. Not all people are capable of out performing an ABS system. You decide.

compu_85 · #7 08-16-2010, 08:28 PM

Quote:

Originally Posted by Renntag

I am not a fan of most ABS or Stability control systems, as in many cases braking distances are increased and certain evasive maneuvers are more difficult.

I would say, pull the system out and sell the parts. Not all people are capable of out performing an ABS system. You decide.

I'll bet you $100 that on anything but loose gravel or snow even the old Bosch 2 ABS will stop quicker then you. You don't have 3 brake pedals which you can pump 20 times a second. Mercedes did extensive testing and found that in almost every circumstance ABS is better then a highly trained driver. Take a look at this article.

I tested the stopping distance in my Jetta with abs v. non abs on snow with excellent snow tires. At 30 mph, with snow over glare ice, the car stopped about one car length quicker with the ABS off then with it on. It was also sideways at the end. ASR changes that car from one wheel drive into two wheel drive in the wintertime. The difference in traction is amazing. That's why I retrofitted ASR

koya1893 · #8 08-17-2010, 09:34 AM

The ABS light on my car 1985 300SD, when you first start the car it's off. However, drive short distance it will be on. where or what components should I look at first to troubleshoot?

Beastie · #9 08-17-2010, 10:08 AM

Koya1893, I had and have same problem. There are some good threads here that discuss this. I found the first thing is to check for proper battery output.
Check voltage with car cold and engine off then with engine on. Low Voltage will
trigger the light. I believe mine is the sensor at the wheel since the light never cam on before new tires were put on the car at a shop I was not familiar with.
I believe there is also an overvoltage relay ? If I can find the thread I will send it to you.
Alan

t walgamuth · #10 08-17-2010, 11:12 AM

I've been driving for over forty years, most of that time without abs. I don't mind having it but have found a couple of intances where it harmed me.

If it costs a lot to fix I would remove it. If it were inexpensive to fix I would keep it.

I suspect since it was disabled it has an expensive problem.

compu_85 · #11 08-17-2010, 12:31 PM

Yes, the ABS and SRS computer are powered through the over voltage protection relay.

The only expensive thing to fix would be one of the wheel speed sensors IMO.

If the light is off when you first start off but then comes on as you drive that points to one of the wheel speed sensors not working. It could be as simple as dirt buildup on the sensor and tonewheel. In fact that might be the exact issue, if there were a hard electrical fault the warning lamp would come on right away.

-J

t walgamuth · #12 08-17-2010, 03:33 PM

Thanks! When I get it running I can check that out!

t walgamuth · #13 08-17-2010, 10:07 PM

PO reports the computer is bad and the relay has been removed under the hood.

compu_85 · #14 08-17-2010, 10:39 PM

So now is the time for a trip to the boneyard. The ABS controller should be the same for any W126 without traction control, and probably any W124 or W201 as well. You can grab the relay(s) too.

-J

hey_allen · #15 08-18-2010, 02:24 AM

Any ideas on what is going on with ABS, if the light comes on at ignition on, goes of and stays off, but ABS does not engage even when locked up and sliding?

My SEC's ABS has never worked in the few years that I've owned it, but I've never really pursued troubleshooting it either.