Turn Signals dead and RPM drop problem...

[Toast]

Hi everybody.:D I came across this site through google, and this site seems to be a great place to ask questions. :cool:

Anyways, I have a 1995 C220 in Canada. Over the last month, the turn signals stopped working intermittently. The turn signal stalk, hazard lights will not work at all (nothing happens when I click either of those). To go with that, the slowerst setting of the wipers doesn't work either (others work though). If I go over a bump, or accelerate/decelerate hard, it sometimes comes back, and then goes away again. :rolleyes: Any inputs? I've done a search and didn't find anything useful. :(

Another problem is I often get a severe RPM drop when the car is stopped (on a red light or something). It appears to happen whenever the cooling fan starts, and when the RPM drops(to about 500RPM), the exterior/interior light dims. When it gets back up, it goes to 1200RPM and then drops back to normal (600-700). What could be the problem?

Thanks for the inputs!:)

[JRE320]

Look's like a wiring harness problem. check this out and if possible bring it in for service asap.

[moebiusgold]

...or a short in the fan circut. My master relay did thje saame thing on the wipers. It was Cheap! But for you its time for the voltmeter. If you don't know what to look for with a multimeter you'll be paying $$$ at a shop. LOL;)

[Toast]

Thanks for the inputs. :) I think this is a serious problem and would like to have it fixed ASAP. (I was making a left turn tonight using hand signals :D , but a kid in a pickup truck behind me didn't seem to see it :rolleyes: ).

JRE320: I think it could be bad contact between connectors, since the problem seems to go away (for a while) when I go through bumps, etc...

moebiusgold: do you have any pointers of how to check the master relay? I think I have a voltmeter somewhere at home, but I have no idea where the test should be done.

:D

[jnolte]

i think it is the wire harness also!

[nokia8860]

Im surprise moebiusgold didnt mention his own post (http://www.club202.com/forums/showthread.php?threadid=2258) Because you said both your wipers and turn signals seem to malfunction it could be the very same relay moebiusgold replaced. coud be

However unsure about your dip in rpm. I wanna say charging problem as your fan kicks in, your lights dim and your car stumbles.

[moebiusgold]

Originally posted by nokia8860
Im surprise moebiusgold didnt mention his own post (http://www.club202.com/forums/showthread.php?threadid=2258) Because you said both your wipers and turn signals seem to malfunction it could be the very same relay moebiusgold replaced. coud be

However unsure about your dip in rpm. I wanna say charging problem as your fan kicks in, your lights dim and your car stumbles.
Yep. could be. Loss of voltage would make everything weird. I mentioned ground because the most bizzar car electrical problem that I have had today (not on my Cs at least) was when a ground was lost and turning something on would relult in it kind of working but something else like brake lights suddenly "half on". This just took as much time as it would to answer this properly with a multimeter. PS, I didn't mention my post because.
1) I felt like a dummy when I posted it. I'll never forget where that's at! (but Thanks again, none the less)
2) That's what the search button's all about
3) I was hoping to see a reply post like this voltage was that, and this was .....and when I turned on this, that droped to...

Without more data (for me at least) I can do no more than guess.
Wouldn't the excessive low idle generate a code? Are there low voltage codes?
I don't even have a wiring diagram so I couldn't even tell you if the maste relay controls everything that you are having problems with.
When you fix it, let us know so that we may all be smarter about our "C"s.:cool: :)

[moebiusgold]

Originally posted by Toast
Thanks for the inputs. :) I think this is a serious problem and would like to have it fixed ASAP. (I was making a left turn tonight using hand signals :D , but a kid in a pickup truck behind me didn't seem to see it :rolleyes: ).

JRE320: I think it could be bad contact between connectors, since the problem seems to go away (for a while) when I go through bumps, etc...

moebiusgold: do you have any pointers of how to check the master relay? I think I have a voltmeter somewhere at home, but I have no idea where the test should be done.

:D Check voltages anywhere you can get at a connector or fuse block terminal. Start basic. Check the voltage at the battery (BTW, the most obvious place for a high resistance connection, at the terminals) as the fan cycles etc. If this barely drops, check at alternator.
Basic quetion put the headlights on Hibeam and turn on the fogs. Do the lights get dim when the fan comes on etc? System wide low voltage could make things like the idle control circut and fuel pump not to work properly. I want wiring diagrams.
Email me. I only live 2 or 3 hours away. If you like I could send you a phone No.:) I still have my old bad one (mster relay) that was only really affecting the wipers. For the price of gas and your time you could have a handful of them though.
My bets on nokia8860 or BenzNL having 10X more knowledge then me on this subject. LOL:D

[nokia8860]

Originally posted by moebiusgold
I want wiring diagrams.


you and i both.

[Toast]

Once again, thanks for the information provided. You guys are great. :D

moebiusgold: Yes, when the RPM drops, all the lights (interior/exterior) goes dim for that second. I kind of have an idea that the alternator is about to go. :( And I've had it looked at a dealer before, it didn't trigger any fault codes. Since we live "relatively" close, can you recommend any good shops that specialize in MBs? I'm having trouble finding a good place to have my car serviced since it expired, and we all know that dealers over charge like there's no tomorrow. :bandit:

Finally, would it be wise to invest in a Bentley manual for my car? Does anyone else have one for their W202? I have one for my car (a 01' 330i), and it seems to help a lot, with a lot of wiring diargrams at the back. :)

[Toast]

If it does in fact involve a faulty wiring harness somewhere, I'm guessing it'll cost a fortune to have someone find out where it is, and then replace it? :(

[Toast]

I've browsed a number of MB forums and came to a conclusion that the combo relay seems to be a common problem as the car ages. I have pulled the one on my car out, and it has a part number 201-821-00-47. Since it appears to be a ~$60US part, I guess I'll start by replacing that and see what happens.

One more thing, when people talk about replacing the relay (or combo relay, as its most commonly referred to as), they mention the part number 201-821-02-47 which is different than mine. Are they all the same? :)

Thanks for reading. :D

[Tump43]

As per the moderators' instructions I'm resurecting this post because I am experiencing a related problem.

Just today, my turn signals (left and right) did not come on when I moved the stalk to indicate a turn. At the same time, I could not turn on the winshield wipers or the washer fluid with the same stalk. I also tried the horn and it did not work. Strangely, when I pulled the light switch out to turn on the fog lights, neither they nor the led in the center of the light switch came on. My highbeams and the blue indicator light on the gauge panel did work.

About 30 minutes later the turn signals and winshield washers started working normally again, I didn't try the horn, and the fog lights came on but the led in the center of the light switch did not come on.

What could be the problem? I truely need help with this one.

Previous posts here and at MercedesShop.com indicated that this problem could be caused by a faulty voltage regulator (on back of alternator), a bad wiring harness or a bad master relay. However, none of these posts gave the final solution to or the precise cause of the problem.

Any help would be appreciated.

Thanks,

[Tump43]

Well, I took the car into the dealer's for warranty repair and described my problem exactly as I did above. I even suggested that they analyze all the items suggested by the experts here and at MercedesShop.com (grounds on the wiring harness, the ignition switch [EIS], the combination/master relay and the signal activation module (SAM), including the voltage regulator and fuses. All they said was "No defect found at this time." I didn't get to speak to the technician so I do not know exactly what he looked at, if anything, besides the vehicle's error codes.

I did, however, get them to replace both fuel level senders and my inoperable infra red key under warranty so, I can't complain too much. I've also had them rebuild my othopedic driver's seat; replace my automatic climate control unit; replace the harmonic balancer, the a/c compressor w/ clutch, condenser, temp sensor and a/c drier; replace the radiator, steering damper, outside temp sensor and fuel shut off sensor; remap my transimission; and replace the driver's side view mirror motor, all under warranty. I believe that this is worth more than the $1,700 I paid them to extend my Starmark.

My original electrical complaint is documented as having occured prior to the expiration of my starmark warranty so, I hope that should this electrical problem surface again they will take care of it under warranty or goodwill.

Hope this helps,

[Toast]

Hi Tump43,

Last year I bit the bullet, went to the local dealer and ordered the master relay in hopes that it'll fix the car immediately so I can drive it. It turns out that the master relay is the problem. I bought the relay (a $250 Canadian part, no less), replaced it myself (a 30 minute job if you're slow like me :D ) and all has been working fine since. It fixed my turn signal/wiper/horn issues, but I still have fluctuating rpms whenever I'm stopped. I guess the 2 problems are not really related. But if the turn signals/wipers are your only problem, it should be fixed with the master relay. Hope you find the information helpful! :)