ABS warning light

[GazCaff]

I got into my car at the end of work today only to find the ABS light remained on and in addition to that my cruise control is not working.

Although I've searched, I couldn't find the exact same problem on the forum, but related problems posted seem to point towards a faulty brake light switch (my brake lights work fine btw). Would changing the brake light switch be a good place to start.

Please give me some guidance as it drive me up the wall having a warning light on the dash and I really miss the cruise control :(.

[Aletank]

It could be your brake light switch, about £10 or a ABS Speed Sensor, I paid £50 for a front one recently. If its a Speed Sensor your automatic locking of the doors at 5mph would of stopped working and cruise control also.
Do a search for Speed Sensor, here's the thread I used http://mbclub.co.uk/forums/showthread.php?t=27473&highlight=speed+sensor
If it is a speed sensor, you need to find out which one it is, I went to my local Indy with the problem, he put it on his laptop and told me, I then said I'll book it in with a service in a few weeks. I then went the dealer and bought the part and fitted it myself ;)

[kris30]

Hiya, I had the exact same problem, I did all the usual stuff, checking the phonic wheels, sensor pick ups, resistance down the lines to the sensors, on joy. Had to take it to the MB guys, thinking, ouch, big bills. In the end it turned out to be the Stop Light Switch, £35 (£10 for the part) pounds later all fixed.
I've seen somewhere since on the forum, Pictures of where it is located and how to change it, sorry no idea where, a fair way back in previous posts i think with a link somewhere else.

cheers, Kris.

[noops]

I had that problem and my local indie confirmed my fears that it was a faulty brake switch, it cost me £47, £7 for the part and £40 labour and now it works perfectly.

[GazCaff]

It could be your brake light switch, about £10 or a ABS Speed Sensor, I paid £50 for a front one recently. If its a Speed Sensor your automatic locking of the doors at 5mph would of stopped working and cruise control also.
Do a search for Speed Sensor, here's the thread I used http://mbclub.co.uk/forums/showthread.php?t=27473&highlight=speed+sensor
If it is a speed sensor, you need to find out which one it is, I went to my local Indy with the problem, he put it on his laptop and told me, I then said I'll book it in with a service in a few weeks. I then went the dealer and bought the part and fitted it myself ;)

I don't think my car has automatic door locking. If it has, its never worked!

I bought a new switch today (£8) I'll fit it tomorrow.

[wongl]

I don't think my car has automatic door locking. If it has, its never worked!

I bought a new switch today (£8) I'll fit it tomorrow.
If your car has automatic door locking (my 1997 C180 does, but not my 1995 C180), you have to enable it. This is done by turning your ignition key to positon 2 and then pressing the upper part of the central door locking button on the dash and holding it for 6 seconds. When you next drive off the doors will auto-lock.

To deactivate, turn the ignition key to position 2, press the lower part of the switch and hold for 6 seconds.

[GazCaff]

I fitted the new switch today and it hasn't cleared the fault :(. I even disconnected the battery for a few hours to see if the fault needed clearing but still no joy.

I'm wondering if a fuse has blown for the abs, can anyone tell me which fuse to check before I go checking the sensors?

As for the auto locking doors, I checked the hand book and it makes no mention of auto locking doors. My car is a pre-facelift model.

[GazCaff]

I'm at a loss now. I've trawled the web without any success on this issue. Is there anywhere I can get the fault codes read for the ABS and cruise without being charged a fortune? :(

[kris30]

Hiya, shame about the switch. Fault codes, I had mine read by a local garage, they didn't even charge to read them! I think most garages have readers, mainly because most cars have diagnostic ports. shouldn't cost alot, even MB only charged minimum cost to read the codes. Definatly worth while having them look, otherwise you could wasting loads of time searching for the problem, you can still fix it yourself :)
Kris.

[GazCaff]

I don't suppose anyone can point me towards a decent wiring diagram for the W202 on-line? I'm going to prod around with my muli-meter tomorrow and see if I can get to the bottom of this.

[GazCaff]

Well I prodded around with my multimeter like I said I would and found the nearside front sensor to be open circuit. I'm going to order a new sensor tomorrow. I can only asume that the cruise takes its speed sensing from the same sensor which explains why it has dropped out. At least when I get this fixed I'll have a spare break switch for when I need it :)

[Aletank]

Well done - what a result !! :bannana:
When I ordered mine the parts guy said i need a new sleeve for it as well(about 50p) but i didn't really think i needed one once i got it off, but what i would recommend getting is 2 new bolts for it. They are the star shape head and mine was pretty rusty and there was a good chance of them rounding off with the conditon they were in, since changing the sensor i have had the wheel off again and fitted 2 new bolts(£1.50 for 2)
Good Luck