smooz

Folks,

BAS ESP light is on. It comes on minutes/seconds after startup. I have replaced the brake light switch multiple times. Interestingly, the cruise control works. No ABS issues.

Anything else I should check to help you diagnose?

More of an annoyance than anything else.

Any ideas?

Thanks much,

Greg

perbilse

Hello all,

I have a similar problem. My car is a '99 pre-facelift E430, and when it gets a bit hot under the bonnet, I get ESP, ABS, and BAS failure right after one another. The problem only manifests itself in the summer, and then only when I get stuck in a traffic jam and sit idle for 10-20 minutes, ie when it gets hot under the bonnet (hood). After the problem has manifested itself it remains until the car has cooled off, either by stopping and leaving it for a while, or by driving at good highway speed for 10-15 minutes (of course, needs a stop and restart to actually reset).

It hence seems very clear it's related to temperature, but I can't find any mention of what actual problem is triggered. Possible causes I've seen on various fora are either:

1: Corrosion and/or poor electrical contact for the ground screw behind the ABS/ESP controller.
2: The (brake light?) switch on the brake pedal.

There appears to be no problem with the grounding screw in my car, everything is clean and shiny, with no corrosion. As for the switch, my brake lights work at all times, so I figure it's fine. Or, does the switch have some odd intermediate failure mode? I've actually never seen any explanation for how a fault with this switch could trigger a cascade of ABS-related faults. Does anybody know?

I've been wondering if it might be the vacuum servo that doesn't deliver enough pressure when idling under hot conditions, but I don't have any conclusive evidence.

I haven't taken the car to a Mercedes dealer for diagnosis yet, they easily charge $200 just to say hello around here (London, UK), and diags at independent garages can be a bit hit or miss.

This seems to be a recurring problem for many people, so it would be great if anybody had some definite answers.

Thanks, best,

-- Per

emncfi

Could also be your lateral yaw sensor. Its about a 1 inch cube thing under the center console just aft of the shifter

Merc Tech Knysn

Hi guys my slk alternator overcharged, got that sorted now, but the esp/bas light illuminate only when I'm driving and depress the brake pedal and will stay on for the rest of the trip until the ignition is turned off and if started again its gone till I drive off and depress the brakes.

I did a scan and diagnostic code C1529 came up. also p2014 camshaft timing solenoid have replaced this already. only show the p2014 code if the engine light comes on.

emncfi

There is also a second part of the BAS ESP system that has a switch on the back of the brake pedal, good news is that sensor is only about $30

Merc Tech Knysn

just a update from my previous post it turned out to be a bad abs/esp control unit.