S500 intermittent problem
 

I hope you can help! I have a 1995 Mercedes Benz S500
with 107,000 miles -pampered miles. I do not drive the
car in the winter when there is snow on the ground. My
problems started last fall, about 5000 miles ago. The
car was serviced - oil change and what ever they had
to do. With the first day that the weather dropped
below 32, the windshield washer bottle froze, only I
did not know it was frozen and try to use the
windshield washer with no results. So I dropped it
off with the mechanic who informed me that the washer
motor burned up and melted the washer bottle. (the
service station repaired the problem at no cost).
About 3  5 days later I could smell wires burning, so
I took the car back. They replaced the ignition wiring
harness under the dash. Two days later I shut the car
off to run into the store but when I came out, the car
would not start. So I towed vehicle to the shop where
they replaced the starter. 1 week later all the
warning lights came on: replace alternator and
battery. 2 days later while driving on the highway,
ASR warning light came on and power was reduced, but
the car still ran. I phoned the shop and they told me
to pull off the road and turn the car off then restart
and bring it in to shop. This time they replaced
battery again and the car ran fine for 3 days then
the same problem - ASR light, reduced power, return
car to shop, replace battery again ( thank god for
battery warranties!). 3-4 day the SAME problem - ASR
light, reduced power, back to shop - they could not
find the problem I let the mechanic keep the car for a
month the problem was intermittent and they told me
the transmission wiring harness had to be replaced, so
they replaced it along with a neutral safety switch.
The mechanic drove car again and said it did not have
any more problems - each time it was in the shop they
hooked it up to a computer. Picked up car and 5-6 days
latter the same problem - ASR light, reduced power.
Next I took it to the Dealer - they put it on the
computer and said it needed an engine wiring harness,
so they put a new one in. Computer tested everything
OK. They even did whats called a socket box test
which took 5 hours. I picked up the car yesterday - it
ran great until today, and guess what? The same
problem! I have no idea what to do or what to try and
am hoping that you can solve this mystery for me

Ed

I am not a mechanic and have no idea what your problem is, but it appears your car is going into "limp home" mode.

You might find something in the archives.

Here are the results of a search for "limp home":

http://www.peachparts.com/shopforum/search.php?action=showresults&searchid=463315&sortby=lastpost&sortorder=descending

SAME THING HAPPENED TO MY DAUGHTERS 92 400E...TOOK MONTHS TO FIND PROBLEM...IT TURNED OUT TO BE THE THROTTLE BODY...ITS EXPENSIVE...FIRST REPLACE BRAKE LIGHT SWITCH ON BRAKE PEDAL AND GAS PEDAL SENSOR SWITCH ON UPPER GAS PEDAL ARM...MAKE SURE BATTERY IS CORRECT BATTERY...IF YOU TAKE TO M/B SHOP THEY CAN READ WHATS STORED IN COMPUTER TO HELP DIAGNOSE PROBLEM...ENTIRE CAR ELECTRICAL SYSTEM IS PRETTY SENSITIVE AND TURNS ON ASR SYSTEM GIVING LIMP HOME MODE. JUST BE GLAD YOU ARE NOT ON A FREEWAY AT 7OMPH WHEN THE ASR TAKES OVER CAUSE YOU COULD CAUSE A SERIOUS WRECK...HEED MY WARNING AND GET TO MB SHOP...MB HAS LOTS OF TROUBLE WITH THROTTLE BODY FAILING.

The throttle body is probably a likely suspect.

On W124 chassis cars with the M104 engine cars with ASR, it is usually the throttle actuator which causes the problem.

i also just remembered the limp home mode can be caused by a defective switch on the transmission located near the tunnel on the drivers side.