The symptom for this is a BAS/ETS light stays on for a while and then shuts off for no reason. timf on Benzworld wrote up these great notes on how to replace it: If your BAS ETS warning light occasionally illuminates for no apparent reason, stays lit for a while then mysteriously resets itself, you most likely have a faulty brake pedal switch. This is a fairly common ML problem and most MB dealers will likely stock the replacement switch, part number 001-545-31-09. Here's a picture of the offending part taken on a genuine ML floor mat. Fortunately the part is inexpensive ($13 plus tax) and easy to replace. Anyone who can handle a screwdriver and has ½ hour to spare should be able to perform this repair. Now read on to save yourself a few bucks, fix the BAS ETS problem and have a closer look at the fine engineering of your ML (plastic accelerator pedal assembly excluded !) Start by removing the cover which goes round the brake and accelerator pedals. Do this by first removing the two large 1” diameter plastic nuts shown here. I’ve found a large bladed flat screwdriver works well to rotate them anti-clockwise. Having removed the plastic nuts, remove the two black screws shown here in these two pictures. This picture was taken from a different angle. Carefully pull the plastic cover away, but take care as the OBDII connector will still be attached. For better access remove the OBDII connector from the cover by sliding the retaining latch to the right as shown here. Set the plastic cover aside out of the way. The brake switch can now be seen in position just above the brake pedal. It is easily removed by depressing the tab and rotating it 90 degrees clockwise. The switch should now be free and hanging by its leads. Make a note of the connector locations and orientation then disconnect them both. Discard the old switch (or save it for later examination !) Re-connect the cables to the new switch taking care to orientate them correctly, the re-install the switch. Make sure the locating tab clicks securely into the bracket and that the cables are not snagged on anything. Out of interest, take a close look at the accelerator pedal assembly – what a cheesy set-up. No wonder some owners complain of slack or wobble. Also take a close look at the distance between the brake pedals resting point and how far it needs to travel before it starts to exert pressure on the brake master cylinder – hmmm interesting eh ? Anyway, your nearly done ! Re-attached the OBDII connector to the cover by relocating the connector then sliding the latch back to the left. Make sure the OBDII connector is firmly fixed in place, then put the cover back in place. I found it easiest to secure the cover in place by means of the 2 black screws first, the re-fasten the front in place with the black nuts. Finally turn on the iginition and check that your brake lights work – hey you might even find you have an unrelated blown bulb ! AC_ML on Benzworld also noted: Great document on this common problem, and your instructions work perfectly, too, for fixing up the sticky gas pedal problem by applying lithium grease(or prefered lubricant) to the sticking pedal plastic hinge. Never had that nasty sticky/notchy gas pedal problem again after I greased the gas pedal hinge.