W220 intermittent failure to start - PeachParts Mercedes-Benz Forum

95s420 · #1 05-23-2006, 12:12 PM

A weird thing has begun occurring on my 2000 S430. From time to time when I go to start the car absolutely nothing happens. It does not turn over at all. However, if I return the key to the off position and go to try to start it again it starts right away. There appears to be no effect on driveability or performance. Just seems that about 50% of the time I have to try to start the car twice before anything will happen.

Any ideas on where I might start?

Thanks!

mbdoc · #2 05-23-2006, 12:22 PM

If you insert the key...wait 2-3 seconds will the engine start every time?? IF you try your SPARE key does the same thing happen??

95s420 · #3 05-23-2006, 12:29 PM

M.B Doc,

Not sure about either of those. I will start by waiting 2-3 seconds and then trying to crank the engine. If that does not work I will switch to the spare key. Thanks for the advice.

Brian

95s420 · #4 05-23-2006, 02:09 PM

Ok, went out to start the car at lunch and it refused to start at all. I tried it several times then gave up and went with friends to lunch.

When I got back I tried it again, it started. shut off and tried again and it would not start. Finally, after several attempts to start I take the car out of gear and back into park and it starts every time.

So, I now remember several days ago having the car start but not being able to get it out of park.

Does anyone know if the "shift interlock" might be causing all this and if so where it is located?

Thanks for all the help.

Brian

95s420 · #5 05-23-2006, 03:04 PM

After reading through all the archives it looks very much like either the shift module $600 or the brake light switch $20. I think I will try the brake switch first and hope that fixes it.

Thanks

95s420 · #6 05-23-2006, 07:43 PM

OK,

Purchased and installed new brake switch but did not fix the problem. I also tried waiting 2-3 seconds before starting and that does not seem to make a difference.

I grabbed my spare key and will start using it tomorrow. We'll see if that has any effect on the problem.

From what I can tell....it appears that the problem occurs when i dont hear the shift interlock operating. If i hit the brake and hear the interlock operate it always seems to start.

Starting to think maybe it is a defective shifter module. Is there anything else besides the brake light switch that would cause the interlock not to operate?

any other ideas?

Thanks

95s420 · #7 05-23-2006, 09:41 PM

Buckwheat,

Thanks for the help. The brake switch is the logical and least expensive place to start. I have now switched to the spare key to test the possibility that the first key is malfunctioning. If the key doesnt do the trick I will need to get to the basics like checking for voltage at the starter. Whats odd is that one minute the car wont even turn over and the next it will start like new.

Thanks again for you help.

Brian

miamijin · #8 05-24-2006, 12:00 AM

i just bought my first mercedes today ... to get into wvo fuels ... the 300d did not start sometimes ... the old owner used a piece of wire under the hood

to start the car if it did not start daaaaaaaa a little stupid but you could get where you were going if you had to....... i had the simptom happen to me hmmmm did not start .... so i held the key in the start position ... and moved the automatic trans shifter walaaaa it started.....

i will change / clean the stwitch soon ...... i just got the car today ....nice car too 156K miles 1980 300D for $800 ....... soon to be driving on wvo ........ then a diesel generator running my house ac and whatever else i can plug in ... i will keep the refridgerator and the clocks of the local power company....

try moving the shifter to narrow down the cause of your problem

95s420 · #9 05-24-2006, 08:58 AM

Well,

tried the spare key but the car still refuses to start from time to time. However, I am really narrowing down the cause now. I notice that when I dry shift the car when it refuses to start then it will always start next try. I was hoping it wasnt the shift module because of the cost.

Do you guys know if there is a sensor on the vehicle that checks if the car is in "park" prior to starting. It seems like this is the sensor that is bad. I am guessing that it is in the shifter but I want to be sure before dropping the dough.

Thanks again for all the help!

Brian