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ABS light

2K views 7 replies 5 participants last post by  rowdie 
#1 ·
I have done a fair bit of searching on this but to no avail. My problem is the ABS light comes on once the car is started and stays on. If i restart the car it will go out. But if starting from fresh it comes on and stays on. The car has a new battery so doubt its low voltage.

Any ideas? I will try and clean the earth strap which is meant to be by the unit in engine bay. Should I look at the sensors? I 've read these mainly show up in an intermittent way and would mean the light wouldnt go out?

Thanks,

Rohan

car is a 1984 280 sl.
 
#2 ·
OVP relay could be playing a role here.

However...I didn't thing an 84 280SL would have one...let alone ABS brakes.

But what do I know about UK models?....Not much. :)

Standby....someone smarter is sure to come along shortly.
 
#3 ·
Fonzi posted a link about basic trouble shooting on the ABS. Mercedes Early ABS Brake System Troubleshooting Repair by Kent Bergsma - YouTube Kent Bergsma, Mercedes Source is a good source for info. on Mercedes.

Ground strap cleaning can't hurt. Sensor cleaning is covered in the video. And ABS was an option. Don't know what year it started. Fonzi has it on his 1981 280SLC and I have it on an '84 280SL.
 
#4 ·
Not sure about those early cars, but on later cars the brake light switch usually has two sets of contacts. If the switch does not work properly, the ABS light comes on. Usually an inexpensive fix.

Bear in mind - I know zip about that particular ABS system.
 
#5 ·
Ok guy, i will clean the ground, then have a look at the brake switch. I am unsure on what to do with the OVP - if this was bad wouldnt I have other problems or should I say the car! Is there something to look for on it in particular?

THanks for the help!
 
#6 ·
It was an option in 1984 and became standard on 500SL in 85.

The controller checks itself, the speed sensors, the pressure modulating valves and the wiring harness and switches on the lamp when faults are detected. The lamp is also powered during start up, if a fuse is blown or if the OVP is faulty.

My system has failed a few times due to front sensor cable breakage and once caused by wiring insulation in the RHS footwell being melted due to brazing work. In all cases the fault would often clear itself when switching the ignition on and off.

I would start the car, ensure that the warning light was not on and then pull and move the sensors wires in the front wheelwells to recreate the problem. If the light comes on you will know which sensor is faulty.
 
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