W163 ABS lights extinguish when fixed or reset?

[miggit]

Hi, got the pain in the neck orange lights blinding me, inc bas,esp,abs.

Right so I've had the car for 4 years now and everytime it gets drowned the 3 orange lights come on... but the next day all is good. I had it on a snap on diagnostic tool and it said rear left abs sensor. But the mechanic who read the fault said to replace the 2, as sometimes the diag. tool didn't know it's left from right.

So I got the sensors, discovered that the old one weren't going to come out without a fight, so I put the wheel back and lived with the ABS not working for a day or two, probably 4 times a year.

But after last weeks drowning the orange lights are refusing to go out, even after the brakes have been slightly cooked... which normally does the trick.

So I'm facing having to drill the old sensors out the hubs, ect. But I can't help having that nagging in the back of my head that it's a chaffed loom, either behind the headlight or under the fuel tank area...

So the big question is... If I just plug in the new sensors (leaving the old ones in place) IF they are the fault will the orange light go out without having to move the car? That way I can tell if it's worth spending a few hours changing the sensors, or find out that my time would be better spent behind the headlamp and under the car!!

 

[91dm]

Bit of a coincidence, I'm just after fixing mine after two years!

Had similar issue on and off for a long time until one day stayed on for good, must of been the wire on its last strand.

Turned out to be a broken wire down by the connector behind the light (have thread created with codes).

All codes had to be cleared before lights went off after being repaired, didn't require to be moved for me anyway!

Hope that helps.

 

[miggit]

That's good to know, think I'm going to be just plugging in the new sensors, not fitting them, to see if the lights go out...... I reckon that the light is gonna be coming out.... but I can live in hope!!

 

[91dm]

I would check the harness first, it's an easier job than the rear sensors?

 

[DSM10000]

That's good to know, think I'm going to be just plugging in the new sensors, not fitting them, to see if the lights go out...... I reckon that the light is gonna be coming out.... but I can live in hope!!

Unless the new sensors are in place and able to detect the hub then they will likely still show a fault?

 

[Bellow]

So the big question is... If I just plug in the new sensors (leaving the old ones in place) IF they are the fault will the orange light go out without having to move the car? That way I can tell if it's worth spending a few hours changing the sensors, or find out that my time would be better spent behind the headlamp and under the car!!

At a guess - not gospel - if the sensors (not the wiring) are at fault new ones will be seen as good at start-up so the light should go out (maybe a few start-ups required), but as DSM1000 suggests, the lights will come back as soon as the car is rolling and the ECU doesn't get the expected signal(s).

 

[miggit]

Well the plot thickens... I was parked down hill yesterday for sometime.. most of the day.. I started the car and the lights went out !! But the instant that I hit level ground the dash lit up like a christmas tree and that was it until I turned the engine off. So as suggested, I think that the issue is the loom, not the sensors... time will tell..

 

[Bellow]

Was the weather wet?
Migrating water droplet to chaffed/exposed wiring a possibility.

 

[miggit]

Well things just keep on getting more mysterious... I fixed the Air Bags with an emulator for the seat sensor, that worked great... then I pulled the ML's left eye out and had a very good rummage into the depths. The loom showed no signs of rubbing, just to be safe, I stripped all the wrapping and checked every wire, and all were perfect. So I re-wrapped the loom and covered the sharp edge of the body with a bit of split braided hose... and that's as far as I got before wilting.

This morning the Air bag light went out and the 3 ABS stayed on.... filled up with fuel turned on the engine.. the 3 ABS lights went out and the Air Bag light came back on.. D'OH!! It stayed like that for a few hours until I turned off the engine and started it again B*#@er all 4 lights back with a vengeance.

Having read many root causes of the ABS lights, I am beginning to think that my ABS motor may well be on its' last legs, as the cars just run in at 272K... So I've got the bits to rebuild it on the way.

My thinking is that despite the fact that after excessive drownings the ABS system got the hump and sulked for a few days, this was not the cause of the permanent ABS light state. That has been caused by the slightly well worn brushes in the motor, and every now and then after the 200th pothole it all makes contact to extinguish the lights.. until the next pothole. And please bare in mind that I do a lot of off road towing, fields and cart tracks, and I've covered 1.5K in the last 3 days... So it's getting well shaken up!

If I get a free day then I'm going to throw on the new sensors and check the rear loom, but the more I think about it an ABS motor that's done 272000 miles is entitled to be a little worn out!

 

[91dm]

I originally thought it was the brushes in mine as it would work on/off, however changing them made no difference, they weren't even that worn at 175k miles. How far did you check the loom, from the connector all the way behind the washer bottle?

 

[miggit]

I stripped the first 6-8 inches from the plug....... are you telling me that they chaffe behind the washer bottle too?

 

[91dm]

Mine was close to the plug but underneath the washer was very wet and had some rub marks in places.

Soldering in new brushes on the motor wasn't a great job to do, pump came off with the shaft, was a nightmare to get back in. There's a guide on the forum somewhere for doing it.

 

[Baldbloke]

Found on the E class that one small ABS fault created all kinds of things becoming inoperative. One Reluctor ring replacement later and power steering, cruise/radar all worked again along with all the warning lights going off.


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[miggit]

Well it's taken some time, but I've managed to extinguish 4 out of 5 orange lights on the dash
First I changed the rear ABS sensor.... and the ESP light came on as well and cruise control packed up, D'OH!! So I reversed that, until I can get another sensor. I then set about the ABS pump, fort the washer bottle.. it really didn't want to come out or give up it's electrical connectors, but I triumphed in the end! The pump was a doddle to remove, although I nearly pulled the needle roller out of the ABS body, it was just hanging in and I managed to push it back. It is not helped by the fact that you can't see it until its too late.

And then the fun started... do you think that the motor cap would come out... NO... all those youtube videos, just grip the shaft and pull... piffle! I ended up having to pry it out with a couple of screwdrivers, it looks like the motor body had corroded somewhat and was hanging on to the big silicone seal. The rest went like the videos and was non-eventful, however on rebuilding the motor I decided to leave the original seal out altogether and seal it with a bead of instant gasket.

And then the moment of testing turned on the engine and all the lights were still on, D'OH!! But 20 yds along the road they all went out, except the airbag light, which is a different problem... cured that one with a module for the passenger seat, then it failed again 10 days later.. either a wire has come loose inside the little black box from Ping Pong, or the whole thing has FUBAReD and I'll have to replace it with one of 4 times the cost!

 

[91dm]

That's good to hear, so brushes in the motor sorted it? The roller came out on me and it has a total nightmare to get back in, wouldn't recommend!

 

[miggit]

Yes new brushes and bearings!

As for the roller / needle bearing, it is totally obscured by the electrical connector from the motor to the ABS block... this was something that isn't really covered in the videos that I saw.. the thing is to get a small screw driver in between the motor and ABS block asap, long before the electrical connector has disengaged, to slide the needle bearing / collar off the motor shaft and hold it into the ABS block.

Hindsight is a wonderful thing!!