leave it to Mercedes to come up with a way-too-complicated single module for three completely unrelated functions. my intermittent wipers on the 1990 300E had gone intermittent, so I replaced N10, part number 2018210047, with the current equivalent, 2018210247... opened up old one to see whats in this silly thing, which manages the turn signals and emergency flasher, the wiper intermittent mode, and the rear window defroster timing.
nothing obviously cooked, way too complicated to want to bother to try and troubleshoot.
Just ran into a similar situation with my son's VW GTI. The module they call the Fuel Pump Relay was in trouble and when I opened it up it had lots of SMDs like that module you opened up and logic chips. What happened to simple relays? At $72.00 the new one was about twice as expensive as it should have been; I shudder to think what the MB module cost from a dealer.
And opposite of what happens with our 124 fuel pump relay fails, the VW relay picks and holds but doesn't let go when the key is turned off. The pump stays activated until the battery dies...:-(
this N10 is $78 at FCPeuro (for genuine mercedes).
if that was an older GTI with CIS injection, the relay might have had the logic to only run the pumps when its seeing timing pulses, a function that was taken over by the ECU in later injection systems.
and, oh yeah, look at 300E... 1990+ CIS-E have the MAS which is a glorified fuel pump relay, with said electronics. even the 86-89 had a relay with the RPM sensor delay in it, running off timing pulses, it also controlled the cold start injector.
The turn signals on my cabriolet stopped flashing so I had to replace this module as well. Fortunately they were stuck "on" so I could "flash" the blinkers manually with the combination switch. I was curious how this could happen so on postmortem I discovered that the contact bead on the relay armature had come off and was wedged into the contact gap (thus effectively keep the circuit live). What are the odds of that.
It struck me at the time that the design was way more complex than it needed to be. The 8 pin SOIC near the 2.2 mfd capacitor on the right is the U243/U2043 automotive flasher controller chip, which, with five passive components (including the aforementioned capacitor), completely implements the turn signal flasher function. That means all the rest of those components are dedicated to just the wipers and the defrost timer!
BTW, I wonder if the defrost timer circuit has a low battery voltage drop-out function like the controller on my Gwagen. That might explain some of the extra complexity.
well, that chip plus passive stuff plus 1 of the relays...
the ST2904 8-pin chip is an op amp. the 20 pin JWT DB 02 A61A8945, I can't find. guesing 8945 is a date code (45th week of 1989, thats pretty standard encoding in chip-land), but I can't find anything on JWT-DB or any other combination of those letters and stuff.
Just out of of curiosity I hooked up my old module on the bench to a variable power supply just to see if there is some sort of low battery protection function (good thing to implement with an Op Amp). Much to my disappointment, the defrost relay dropped out at about 7-8 volts which is about what one would expect for just the relay and way to low for battery protection. I was hoping to find some hidden functionality in all those extra parts.
Just out of of curiosity I hooked up my old module on the bench to a variable power supply just to see if there is some sort of low battery protection function (good thing to implement with an Op Amp). Much to my disappointment, the defrost relay dropped out at about 7-8 volts which is about what one would expect for just the relay and way to low for battery protection. I was hoping to find some hidden functionality in all those extra parts.
I think there is a function though that if the rear defrost is engaged and battery voltage is too low the little amber light flashes on & off in the defrost switch as an alert.
I've never seen the idiot light for the battery ever come on in my dash..even when the battery was discharged. Fooby explained that before...it seems like one of the lower harness wires to the alt has to be damaged maybe....don't remember.
My nemesis is the courtesy light panel overhead. As the IC's in that fail, I get all kinds of strange occurrences. Right now I have front door puddle lights, but no overhead lights come on when the front doors open, either side. Yet the overhead lights work fine manually. I usually just put another JY unit in there and everything is restored. The seatbelt light in the last unit went batshite crazy on me. Jim has graciously sent me another JY unit I haven't put in yet.
the dashboard light indicates the alternator isn't charging the battery. it doesn't indicate anything about the battery voltage. its also an active part of the alternator circuit, the light MUST come on with the ignition key to provide 'bootstrap' current to the alternator field coils, then when the engine starts and the alternator is generating power, it must go out.
Hmmmm...my alt was not charging and the whole car shut down from a nearly dead battery. Still no battery light came on as I remember. What I do remember is that if the battery's running voltage starts to drop drastically, the SRS light will come on and then followed by the ABS light. If the two trouble lights come on at the same time and stay on, my car is ready to electrically shut down.
With the ignition on, I always see all the trouble lights test on.
I have seen the amber flicker on & off before like that in a parts car I bought which had a worn out alternator. If all lights etc are turned on (Power usage pretty much at max) the amber light would blink on & off & the rear screen heater was de-activiated. If I turned the headlamps off for example & raised the idle a little the amber light went solid. So I knew it was a low voltage warning of sorts. I do think there might also be a similar thing in the heated seats buttons.
The mono wiper quit yesterday on my sons 1993 300E 2.8
Funny since I had already been following this thread (and had thread open at time of wiper failure).
There is no noise coming from the motor/wiper assembly, which leads me to believe the problem is not a stripped gear or the common nut falling off joint problem of wiper mechanism.
To diagnose problem, I first swapped out the relay from my 1990 300SE to the 300E (both use 2018210047). No Change. Wiper does not work.
Next I checked the battery voltage after the car had sat overnight: 12.28 volts on Extech meter. Confirmed using a second battery tester. No problem there.
I have a couple ideas/questions for the next step to diagnose:
1. Would it be possible to apply 12+ V to one of the pin receptacles where the relay plugs in to apply power directly to the wiper motor to verify that it is working?
Anyone know or have reference to exact pin receptacle to apply power too?
2. Would it be possible to disconnect existing combination switch at plug only on underside of steering column and plug in new combination switch to see if problem is with combination switch? (avoid steering wheel removal until proven necessary).
I have done the mono wiper mechanism swap before, just not in a hurry to do it again if not necessary cause it is a PITA.
I know this is not a mono wiper thread, but clearly a few here now are mono wiper savvy.
verify fuse 2 is good, thats the wiper power. fuse 10 provides the power to return home when the car is shut off.
the N10 relay only affects the intermittent wipe mode. if you can find the wiper motor plug, unplug it, apply ground to pin 2, and +12V to pin 5, and the motor should spin. +12V to pin 3 is high speed mode. if neither works, the motor is likely dead.
also, on the same connector, with the motor unplugged, on the other side (the jack from the cars wiring harness), with the wiper switch in 'normal' mode (2nd click), and the ignition on, there should be 12V measured from pins 2 to 5.
And yes, checked/replaced fuse 2 first. I should have included that.
Sounds like I will need to remove the plastic panels and such cause I believe the wiper motor only has a small pigtail, if that. So plug must be under the panels.
I see what you said - 2 speeds from combination switch S4 connect directly to the wiper motor M6/1.
I see also that the wiper motor uses the ground behind the instrument cluster W1.
Hate to pull the cluster (fear of damage to edges), but I do have the MB pulling tools. Might be worth a try cleaning up that ground point before I spend on a new combination switch.
Just out of curiosity, does your windshield washer pump still work? Assuming that it did before the wipers died and that it doesn't now, I would be inclined to suspect the combination switch. What are the odds that both motors would fail simultaneously.
If the intermittent feature is a separate circuit and contacts on the combination switch, I would think if speeds 1/2 failed, you would still have the intermittent feature, and visa versa.
I also am surprised that the contacts within the combination switch can support the current load of the wiper motor without needing a dedicated relay.
If the intermittent feature is a separate circuit and contacts on the combination switch, I would think if speeds 1/2 failed, you would still have the intermittent feature, and visa versa.
The intermittent feature depends on the low speed motor winding to operate, so if you lose that, you lose the intermittent function as well. The wiper motor has two separate windings for high and low speed so I find it a bit odd that you would lose both at once unless the motor/wiper mechanism is mechanically frozen.
I believe there's two field windings, but only one pair of brushes and commutator windings. its the brushes and commutator that wears out, that and the bearings.
I thought the wiper motor was a three brush design, but I suppose even if it is, it is possible that the common brush could fail thus killing both high and low speed.
^ This is consistent with my experience. I have never seen the battery light work properly to indicate low/no charging by the alternator. As I have said in the past, its a cruel joke the Mercedes engineers have played on us.
I think it's like the cup holder omission...the Germans figured we'd always be on top of a fresh battery and know when to recognize electrical problems by gut instinct.
We should take a poll here on how many owners have actually seen the bat light come on, while driving a reasonably well-maintained car...lol.
That original N10 relay picture - it appears you have some cracked solder points on the bottom. There's an awesome thread on the N10 on a UK benz site.
My intermittent wipers were working real weird so I pulled the N10, re-soldered a few cracked ones at the bottom and it started working great again. I don't think this was yet mentioned in this thread, however, it's a free step in diagnosing wiper issues. Had to dig on google to find the solution.
That's a pig in a poke solution for that relay, but like you said, it's your free time. Cold solder joints are usually very visible over time. There's a lot of folks that think all cruise controls can be re-soldered and you're good to go....along with OVP's. Probably less than a 10% success rate if that and the OVP should just be updated anyway.
Jeez . . . does having a 200k plus mileage mercedes make everyone an ornery grump or just you? Must be all that money spent replacing N10 relays. Anyone who owns one of these cars and spends time on this forum by default has plenty of free time on their hands, let alone posting close to 9000 times. If we really valued our time we wouldn't own 20+ year old cars that require non-stop tinkering.
At the risk of you jumping on me again . . . would appreciate you helping me understand instead of insulting me how re-soldering an old cracked bead is bad? Cold soldering? I'm pretty sure I got it hot enough for the bead to conform to both the board and the lead.
If that joint lasted 160k before cracking, why wouldn't the newly soldered one last another 160k? All I know is that it wasn't working - I fixed the cracked joints, and now it works perfectly.
lesson learned - last time I comment on a forum I didn't start.
fwiw, MY N10, close examination with a bright light and magnification, I see no sign of any sort of bad solder joint. there was a touch of left over flux on one or two, but when I scratched that away with a pointy plastic tool, nada bad solder. and none of the components show any sign of heat damage.
Probably some proprietary IC's, no schematic....other than fool around with it by parts substitution...what could you do with it?
Kevin
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