ABS Light Gone on ?????????

[BB]

Hi Guys
Just got the wifes car back after many months off the road (Long Story will post details later in general discussion forum)
The ABS light has gone on checked the brakes and fluid all OK cheched fuses all ok
What next ?
It is a 1990 190E 2 litre .
Any clues would be appreciated , also the radiator light came on as well but radiator is full and just replaced the thermostt yesterday . The car was overheating (original thermostat was siezed)
Keep up the good work boys.
Many thanks from down under.
Regards
BB

[philipminion]

BB :

I have a 190 2.3 and I don't have ABS so I'm not sure about your light. I do know that a friend of mine had this problem with his 300e and was told it would be costly to fix it and so he didn't fix it because he decided to sell the car. I never knew what the problem was.

I had the coolant light problem and it turned out that the sensor neded to be replaced. Some people may suggest to try cleaning it first. I just changed it and it doesn't light up anymore.

[BB]

Hey is that the sensor near the water housing near the thermostat or is there one in the water tank where the radiator cap is?
Not too sure its the wifes car and I have to snatch it from her to get to it.
Please advise.
Many thanks in advance.
Regards
BB

[Jim's500E]

Try checking your alternator output or the voltage regulator for wear...any spike in voltage can trip any number of systems to pump out a false code and put on a light. Does your model have a diagnostic plug? Check that before replacing anything large. I'm no expert...just had the same thing happen to me recently...hope this helps a bit.

Your ABS light may be on because your wheel sensors need cleaning. It's an easy job. There is a sensor at each front wheel held in by 2 allen screws (6mm I believe). Remove them, spray them with brake cleaner and wipe em clean. Also spray a liberal amount in the hole while rotating the brake disc. Reassemble with new rubber grommits (OK to reuse old ones if they're in decent shape).

You'll be surprised how covered in brake dust they are. They are magnetic and metallic brake dust makes it look like a fuzz ball when you pull the sensors out. The rear sensor is attached to the differential and should be fine (no brake dust contamination there). Just did mine and it solved the problem.

Good luck.

[pentoman]

Make Sure your ABS ECU is connected properly, on my RHD 1987 it's on the passenger side, behind the battery, near the OVP Over Voltage Protection relay. That's another thing to check - if this is not in, or the fuse has blown, your ABS light will come on. From there, you'll want to check sensors etc. My dads shop has a nifty diagnostic device you plug in, and you then spin the wheels to check if the sensors are working.. there's a load of other stuff it checks too. I'm not sure if its useable on the 190 system, I presume so as its a standard Bosch sys.

I needed a new ECU recently, cost me £75.00 from a Mercedes Salvage co.

later

Russ

[BB]

Whoa lots of clues here, will get onto those ASAP
I did see the magnetic allen screws with fillings on them but did not know what they were, well now I will get into them and give them a good claen.
Will let you all know how it goes.
Once again this forum really does help the car enthusiast a great deal and I sing the praises down ender.
Kind regards
BB

[BB]

Russ
Checked ABS sensor on front disc cleaned as per suggestion (Both Wheels) and checked plug near battery still no luck light still on?
Is there a sensor on rear wheels also re ABS ?????/
Also coolant light still on cleaned the sensor in the coolant tank , maybe this needs changing will do soon . a
Any suggestions where else to look for possible clues?
Sorry for not getting back sooner but real busy and no garage to work from here .
Kind regards
BB

[Alex Vantu]

Check your fuses, Thought they look fine, but do yourself a favor go to autoparts get the new fuses with the glass tube that is compatible with old led fuses. Replace all of your fuses with new ones you will do lots of good for your car.

Alex

[stevebfl]

If your light stays on from initial start-up, it has failed the self test. At this point the only way sensors can be involved is if they are open circuited (disconnected). Dirty, fouled, missing teeth, none of this matters to the initial self test, only continuity.

If the light comes on after moving then something is almost always wrong with the sensor signal quality.

The advise about the OVP relay is good. It is the number one reason for continuos light operation. next is the pump relay or disconnected sensor, and lastly is a bad control unit itself. Oh, and yes lack of alternator output will keep ABS from turning the light off

I had a similar problem with our '89 300E, only it was intermitent. I busted my tail trying to figure it out for almost two years. Basically, it boiled down to two problems.

The alternator wasn't putting out enough voltage, and therefore there wasn't enough juice in the battery to keep the ABS going. The alternator problem was due to an oil leak on the front of the motor. It's called "oil soak", and the oil residue builds up on the armature of the alternator, preventing completion of the current ultimately to the battery. In addition to all of this, the voltage protector to the ABS's brain wasn't working consistently.

In the process of discovering all this, I found out something about the sensors everyone is talking about. They're basically nothing more than tiny electricity generators. They have an internal magnetic plunger that is spring loaded. Every time a tooth on the gear on the wheel passes the tip of the plunger, it causes the plunger to move within the housing. When the tooth passes, the spring pushes the plunger back. This back and forth motion causes electricity to be generated. This is what the ABS brain reads.

I removed my sensors from the car, and hooked up a multimeter to them. I then, in quick succession, moved a steel knive against the end of the sensor repeatedly, watching the multimeters readings. Of course they weren't consistent due to the crude method of my testing, but I did get spikes when voltage was being generated.

Never the less, I let an independent tech convince me that the sensors were bad. Stupid move on my part, as $400 later the problem still wasn't fixed.

So I finally took it to the delership and let them hook up their magic box to test everything. And they are the ones who told me about the voltage protector problem.

Now, since they fixed that and I took care of the alternator, I no longer have a problem.

The moral to this lengthy story, IMHO, is to pay the dealer their $90 for an hours worth of diagnostics time and then fix the problem yourself if you're so inclined.