Ok, these lights are driving me crazy. Just bought this car 3 weeks ago and they intermittently come on and off. I've replaced the brake light switch, twice, both OEM Merc., I've replaced the battery, done the left to right wheel turn more times than I can count... nothing seems to make them stay off (although after replacing the battery turning the wheel L to R did put them out for a while)

I've read post after post but haven't been able to find a fix.

Here's what happened when I changed the switch the second time last night. Lights came on, I turned the wheel to the left, then the right and they went off. Backed up and they came back on again. Got it home, turned it off and back on, no lights. Drove to work today, no lights. Got in it to go to lunch, started the car with my foot on the brake, no lights... drove 10 feet forward... lights came on.

Also, the cruise control works all the time, with the lights on or off...

Help!! Any and all suggestions welcome, thanks in advance!

Check your grounds? poor grounds can lead lights to do odd things.

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hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

I'll try that next but I haven't seen any corrosion or anything that would lead me to believe that's it. Where all should I be checking? Thanks!

Please keep the ideas coming!

A bad ground can be in a lot of different places where the wiring harness connects. Check all connectors, headlights and all, where ever you can, for corrosion. At 12+ years old, your car, like mine, is prone to getting cancer where you can't see it.

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DS
2010 CL550 - Heaven help me but it's beautiful
87 300D a labor of love
11 GLK 350 So far, so good
08 E350 4matic, Love it.
99 E320 too rusted, sold
87 260E Donated to Newgate School
www.Newgateschool.org - check it out.
12 Ford Escape, sold, forgotten
87 300D, sold, what a mistake
06 Passat 2.0T, PITA, sold

Las Vegas NV

Are all the tires all the same size?

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

I should also mention that the BAS and ESP clearly don't work, it's not just the lights coming on.

Check tire sizes and confirm fronts versus back are the diameter, width and height.

All my lights lit up once when the wrong Alt was installed. Put it in gear, step on throttle and 20' later it looked like Xmas. Insufficient voltage and everything stops communicating with the ECU. It all lites up. You can ceck voltage while its running using the CCu. Press and hold REST for 5 secs, use AUTO buttons to toggle to screen 23 or 24.

IIRC there are 3 speed sensors. On at the trans output shaft, one on one of the rear tires and I forget where the 3rd was probably a front tire.

I'd do thess things in the order listed if it was me. Note that a new battery does not mean you have sufficient voltage; the alt could be bad.

If a sensor is bad, there ought to be a code for it; problem is that it takes a high end scanner to read those systems. Something like the dealers.

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

All the tires are new and the correct size. I'll get into the computer and check the voltage. The alternator has been replaced so maybe that's it...

Well, voltage checks out ok- 13.3 - 13.5 with a drop to 13.1 when I turn on the headlights. I've had the codes read and there were a lot of undervoltage related codes...

An update to the light issue... when the BAS ESP and ABS lights come on, the A/C temp control doesn't work, seems to stick on low. When the lights are off, it works fine... I checked the grounds and voltage, everything seems fine. Before I buy sensors does anyone have any other suggestions?

Thanks!

Even though this was on my 1990 i thought I would share. Do the high beams work? See Below:

Replacing the head light fixed the SRS/ABS light problem. But the blower fuse had blown. Not sure if the blower fuse took out the head light or visa versa...

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VegStew
1983 300SD 70,000 WVO Powered miles
1990 300D In driveway with Head Off - Cracked

VegStew, thanks for the reply. I've checked all fuses and the headlights are ok.

What I have noticed is that the power steering is tough when the lights are on. I've cleaned the ABS sensors and rotors and the lights went off after i did that. The next day when driving out of my parking spot they came back on.

These errors are driving me crazy... anyone else out there have any suggestions?

I have one of these cars and had the alternator fail. Big pain in the rear and quite pricey.

If you have a voltage problem the system is running with either shorts in combinations of functions on and off, or the alternator is just not up to the job. When you noted your power steering is stiff when you are experiencing the problem, it reminded me of my alternator problem. Mine would make a clunking noise, which I later learned was the belt tensioner, when it would act up. The alternator voltage would go through some transient event and the load would suddenly get very high, which would add tension to the belt. I didn't do any damage to the rest of the electrical system as my battery kept things somewhat under control, but my belt tensioner was trashed.

A sudden high load from the alternator may slow the engine down enough that the power steering is starved for pressure from its belt driven pump. Just another thought. Good luck,

Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

i had similar problem with my 96E300D. When i bought the car everything was working fine , the next day driving to work im on highway cruising down and beeep! BAS ABS ESP lights came on, cruise control and speedometer stopped working .
I was sick n tired of it that thing was coming on n off everyday, i did some research n stuff, like checked the grounds and all cable etc. but nothing worked.
finally i decided to replace the Relay K40 Unit and Never c the BAS ABS ESP lights again.

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1999 W210 E300 Turbodiesel

I finally took it to an indie shop and had it Star scanned, showing steering angle sensor as current and stored. Replacing it later this week, I hope that fixes it...

Thanks for all the responses!