W202 (1996 C220) Electrical Issues - PeachParts Mercedes-Benz Forum

tobybul · #1 10-30-2008, 12:37 PM

Rear Window Defroster and High Beam Flash

These 2 functions are not working on my C220 and am wondering if they are controlled by the same relay.

I'd like to open up the steearing column and chk the combo sw but i don't think thats the problem with the high beam flash function. My low and high beams work but not the flash function.

The rear defroster does not function. Howver the switch appears to work becasue the sw indicator light comes on when I try to switch it on.

Any ideas

mpolli · #2 10-30-2008, 04:23 PM

My guess is those 2 problems are not related. I would guess the flash problem is a bad stalk switch (I think there is a better name). There have been several threads about those switches going bad. Mine has been fine luckily although it always felt kind of cheap.

On the defroster, That draws a lot of current so even a partially bad connection will cause it to not work. If you can test the voltage at the window connections, both with them connected and also disconnected that will give you some info. For example if you get good voltage when they are disconnected but no voltage when they are connected then there is a bad connection or relay in the path from the battery to the window. On the other hand if you get good voltage when they are connected then the problem is the window element or connections immediately to it. And if you never get any voltage then the relay is not getting the signal to turn on or there is a completely bad connection somewhere.

timmyj51 · #3 10-30-2008, 07:48 PM

Bad combination relay is almost certainly causing the rear defroster problem,
as it was with my '95 C220. Certainly check that before you rip up your defroster
connectors. The relay may also be causing your flash problem. Think,
but not sure, that function is controled by the same relay.

mpolli · #4 10-30-2008, 11:34 PM

I bet timmyj51 is right. I searched on "C220 defrost" and found lots of threads. They didn't seem to mention the high beams though. But it could be related. Seems a little strange though since you say the high beams do work, just not the flash position. I still go with the switch on that one.

tobybul · #5 10-31-2008, 08:51 AM

Thanks for the opinions, Everyone. If only the airbag does not need to be removed to get to the combo switch, I would have checked it by now.

I have this impression that its a PIA to work on although I have never tried it. I fear that I might deploy the bag and that the assembly may not work after I put it back together. Maybe - I better stop thinking too much about it

tobybul · #6 11-01-2008, 09:45 PM

Read my Haynes and it said to chk/feel the relay while the defroster sw is turned on/off. If the relay clicks then the relay should be ok and the problem may be the wiring going to the defroster.

Well, my relay does click so now I gotta look elsewhere.

And, I don't think the headlight flash is controlled by a relay. If so, then it must be the combo sw.

mpolli · #7 11-01-2008, 10:14 PM

I don't know if you read that wrong or if they are just off their rocker, but that test does not prove the relay is good. The clicking of the contacts shows the relay is operating. However, are the contacts inside any good? The easiest way is to remove the relay and jump the appropriate contacts in the socket. If the defroster starts working then the relay was bad. This is sometimes called "jumpering across the relay." Often the connections of the relay are stamped on the side of the relay so you can figure out which terminals to jump.

timmyj51 · #8 11-05-2008, 08:45 PM

Does the defroster switch on your dashboard start to flash after you
turn it on? If it does it means the defroster's not working. Just
put in a new relay (the one we're talking about is in the relay box under
your fuses) and turn the defroster switch on. If it stays lit without
flashing the defroster's working.

tobybul · #9 11-05-2008, 09:10 PM

Quote:

Originally Posted by timmyj51

Does the defroster switch on your dashboard start to flash after you
turn it on? If it does it means the defroster's not working. Just
put in a new relay (the one we're talking about is in the relay box under
your fuses) and turn the defroster switch on. If it stays lit without
flashing the defroster's working.

It stays lit but its not working because nothing is getting heated on the window. I know the relay works because it clicks when you flip the switch.

mpolli · #10 11-06-2008, 03:38 PM

Here is your schematic (I think). If so then you have a combination relay not an ice cube relay. So on this one to run a test you can jumper positions 1 and 6 in the socket and that should turn on the defroster.

tobybul · #11 11-06-2008, 09:50 PM

Thanks. I will try it this weekend.

Next question: After jumping 1 & 6, what would it mean if it works or if it does not

mpolli · #12 11-06-2008, 10:12 PM

Those two terminals connect to the contact terminals of the relay. Those are the 2 terminals that get connected when the relay turns on. When you jump them together it is the same as if the relay did the same thing, the electricity can flow to the window element. If the window gets warm then it means the relay was bad. If the window does not get warm then it means the fault is somewhere else.

mpolli · #13 11-10-2008, 02:07 PM

Welllllll???

tobybul · #14 11-10-2008, 11:37 PM

don't pressure me, man ... didn't get to it..