HELP! does any one know? my car aC220 cdi 40,000 mile, well here it is, I reversed my car out of the drive and the ABS/ BAS lights came on, i drove up the road and all seem okay but could only crawl along, after speaking to a mate that told me to discontect the battery for 5mins then reconnect to reset the computer, the car now drives as normal, but the lights are still on. I have checked all the brake pads all have about 50% pad left. Lights still on can any one help or know what it could be???

 

This condition often points to a fault in the charging system. Check alternator output; then load test your battery. If you're near an AutoZone, they usually will do this free.

Bob

 

The ABS/BAS/EPS systems drop out at low voltage BUT you do not appear from the information provided to have a starting problem = low voltage.

The most likely cause at this mileage is a bad speed sensor or connection (4 one per wheel). Dirty sensors (brake dust on sensor tip) can also malfunction.

Problems often occur during / after rain.

Best bet is to get codes read (and reset) using STAR at an MB dealership (small charge) since this may save you changing components which are not faulty. The code will point you in the correct direction and maybe enable you to correct the problem yourself ratherthan paying dealership prices.

Problem is it could be many things.

Standard wheels and tyres? Tyre pressures correct? Fuses OK etc etc?

Stuart

 

Stuart, thanks for so eloquently correcting my initial thinking and providing the best probable cause and remedy.

Bob

 

Thanks to Bob & stuart .
There is no problem starting all elect power seem okay, so i think as Stuarts says,mybe a trip to MB for a Dia computor check

 

Bob,

I didn't intend to correct you, just offer what I consider a more likely alternative.

You may be correct!

Eloquent. really.

Stuart

 

Stuart,
Yes, eloquent...and knowledgeable!
You Brits do so much better with our common language than we Yanks! I'm glad you were here to get our friend on the correct track.

Bob

 

I'm with Bob oregarding the low battery voltage. FYI, If he battery voltage was dropping down under 10 volts at times which is the threshold for the ESP/BAS system according to the Owners Manual.

If your battery is okay tehen it's your Brake Light Switch that needs to be replaced.

Take care & enjoy the ride,
JOE55

 

This problem occurred three years ago as well, at that time i replaced the brake switch and had the codes reset.. I wait more replys thanks to all.

 

The brake light switch has two circuits. 1 cicuit Normally Open and one normally Closed. These circuits provide the signal for the rear lamps, autogear selector interlock, cruise, ABS, BAS, EPS. ASR etc etc.

AsI stated previously read the codes and this will point you in the correct direction.

MANY things COULD cause your ABS light to come on.

Is your Cruise still working? (This uses one speed sensor..same as instrument pack... and one brake light circuit.)

Is yourASR/EPS working? (Check to ensure the warning light bulb illuminates during prestart check). This would eliminate the 4 speed sensor possibility.

For the battery voltage to drop to below 10v I would expect that you would be experiencing starting problems. You don't state how old the battery is. Expect 4 years MAX.

Stuart