I have a 1998 e320 4matic that suddenly beeped and displayed "ETS" then "BAS" then "ABS" in the diagnostic window, and the associated warning lamps on the left lit and stayed lit. I can clear the diagnostics but the warming lamps never go out.

At first I was able to clear the condition by simply stopping and restarting, but it came back within minutes after restarting the car.

Now it happens every time at start up. I also noticed a loud buzzing noise coming from near the steering column when the key is turned to position two, that lasts for about five seconds.

I took the car into a Mercedes dealership who told me I needed an ETS pump for the low, low price of just $1200 plus three hours of labor and tax.

Now, I'm of the opinion there is an electrical short in this car, because: You can hear the engine in the AM radio, and, you get a shock every time you leave the car after it has been running. I'm thinking this short or whatever it is may have affected the ETS...etc. Also, I think that low voltage can cause similar behaviour. Do you agree? Maybe I just need a new battery, or relay, or to find some short (wish me luck).

If not, your opinions please! Thanks in advance.

Help!

Two more pieces of information.

The night before, I had the car washed at a high pressure drive through wash.

When the problem first occurred, it was the first time since I'd begun driving it that there were five people in the car, and of course all five wearing seatbelts.

Ooh, here's a bit of good detail. Turns out the third taillight, in the rear window, is out.

One dealer we talked to said to check the taillights, but we forgot that one.

Could that be the culprit?

What fault codes did the dealer find?

The only thing I can find on the invoice that look like fault codes:

300

and

62868 traced to faulty ETS...

Bulb replaced. Still no good. Grrr......

Low voltage can cause lots of strange things to happen. I'd definitely make sure the battery is good before wasting time and money chasing your tail. Call your service advisor and ask him/her to fax you a copy of the fault codes. This will give you the code numbers as well as the associated text. That will make it much easier to figure out what's wrong.

Your theory about the "electrical short" is very interesting. I think that there's a simpler explanation though.

It's a safe bet that the antenna splitter behind the left rear interior "C"-pillar trim is loose or poorly grounded. The overwhelming majority of 210 AM radio reception problems can be traced to the splitter.

Do you get a shock after leaving the car after it's been running OR after driving? Tires can create quite a large static build-up after they've been rolling down the road for a while. Try this and see what happens. Before you get out of the car, reach up with your left hand and touch the vehicle exterior. Then put your left foot on the ground. This will ground the car and dis-charge the static electricity. You won't feel a thing.

I'm not sure, but the fault may be as simple as a bad brake switch ($10 part). This part is located above the brake pedal in the interior and is known to go bad. When it goes bad, it believe it trips the ETS light, the third brake light doesn't work, and the cruise control stops working.

I think it's worth a shot replacing this switch before shelling out $1200 to replace the ETS pump.

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95 E320 Cabriolet, 159K

True, the stop-lamp switch IS the most common cause of ETS/BAS/ABS warning lights HOWEVER, if there aren't any fault codes indicating a faulty stop-lamp switch it's a waste of $10.

To properly diagnose the problem find out what codes the dealer found.

As far as the shock thing goes, you don't have to go very far to notice it. Just a short drive and you'll get popped.

I'll see if I can get the codes. Thanks again.

ETS (active) fault code: C1401 (pressure problem?)
BAS (stored) fault code: C1025

That was all they had.

If there's a pressure problem in the brake hydraulics, couldn't it be a myriad of other things, like the master or slave cylinders, or a leak in a line, and not necessarily a $1500 ETS pump? Maybe the pump is complaining that it can't engage because it can't get enough brake fluid?

About two months ago, the car complained about low brake fluid, so I added some brand new, Dot 4 fluid to top off the reservoir and it hadn't complained since, until this new problem occurred.

Either the hydraulic unit is bad or the relay is stuck. In my experience, I've found the hydraulic unit to be the problem nearly all the time. I can count the number of stuck relays I've seen on one hand. Let us know what happens.

I'm assuming "hydraulic unit" means "$1200 ETS pump"?

Where do I find that relay?

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1998 Mercedes E320 4matic
1984 BMW 323e Coupe (the real project)

Yes, the hydraulic unit is the ETS pump. The relay is in the drivers side fuse box. Good luck