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Windshiled wipers not working

9K views 19 replies 3 participants last post by  Dudeman 
#1 ·
Two days ago, I turned on the windshield wipers on, and all I got was some clicking in the seat belt system, and the roll bar light came on.

The wipers don't work in either position (I, II, III or push-in for wiper and wash). My washers haven't worked in a while (some kind of leak in the piping), but the wipers themselves have worked perfectly as recently as 2 weeks ago.

A little background:

A couple of years ago, I had a problem with a bunch of systems not coming on line, or acting up when I would start the car. The Command would cut out, the seat heaters, wipers, seat memory, steering wheel positioning, would not work, and the roll bar light & airbag light on the glove compartment would flicker and the seat belt lock would click rapidly. But it would be intermittent. Then I found that if I tapped on the key a few times while it was on, everything would "reset" and work until next time (usually next time I had to start the car).

All this pointed to the EIS, so I had my mechanic remove and clean the EIS, all the contacts, etc. That fixed all the problems... until the other day.

While I was driving I tried to turn on the wipers, and the familiar roll bar & airbag lights, along with the seatbelt clicking came back, and the wiper didn't move. When I turn the wipers off, the lights go out, and the seatbelt soft release works OK, no clicking. All the other systems work fine, just not wipers.

I thought it might be the same issue as before, so I had the mechanic pull out the EIS, but he said it was clean and he even tried cleaning it some more, but it didn't fix it. So he suggested that the issue might be in the driver side SAM, of which I happen to have a spare. I replaced the SAM, checked all the related fuses (F1 & F5) and relays (A, G & H), but to no avail.

So now I'm left wondering what might be the problem. I don't think the motors die just like this, overnight so to speak, even so, I plan on checking it this weekend.

I know there are 4 wires that connect to the wiper motor, but I don't know what they are, or what volt5ages I should see if I put a volt meter on them Does anyone know what to look for at the wiring harness (what the wires are)?

I assume that if I find voltage on the wire, then the problem is the motor, if not, where do I go from there? Rainy season is coming to No. California, and I'd like to get this fixed.

PS. This is a 2005 SL500 w/rain sensors
 
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#3 ·
I have the WIS manual. How do Ifind the electrical diagram of the car. More specifically, I'm trying to see what wiring goes from where to where, with the wire color coding.

I can see the block diagram, but I guess I don't really know how to read it. I'm more familiar with wiring diagrams that we used to get in the Haynes or Chilton books.
 

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#6 · (Edited)
I think I may have found what I'm looking for.

I found the color coding for the 4 wires going to the wiper motor: Red, Black/Brown, Yellow and Green. In the image below, is the circled connector the wiring going from the SAM to the wiper Motor?

If it is, it will sure make it a snap to check voltages, or alternately apply 12V to the wiper to see if it's working. If this is the case, which wire does what? Without going to the car to check, I would assume Red is 12V, Brown/Black Ground, what about the others?

P.S. @ Rodney: Thanks for the responses both here and on MBWorld. We can use just one forum if you'd like.
 

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#8 ·
I believe the those are the wires. That brown wire should have a blue tracer, and it's not ground - the motor is mounted to ground itself, so all four of those wires are for voltage supply (two speeds) and also for position reporting of the angle of the motor (for parking the blades). I'm no sure which are which, but I suspect green and red are the speeds.
 
#10 ·
solved (hopefully)

Today I put a voltmeter on the connector, to see what's happening.

First of all, with the connector still plugged in, I could hear and feel relay "H" click & stutter whenever I would turn the wipers on. I also tested the voltages on the pins, an the only voltages I found were less than 1V.

Then I pulled the wiring harness, and the relay chattering stopped immediately. I then tested the voltages again, and found 12V on the green and yellow connectors.

So it would appear the motor has gone bad, or has a short in it. Changing it shouldn't be too tough, and the cost of the motor is <$100
 
#11 ·
Long overdue update

Well, storms have been pounding the west coast, and for the past month I've been driving my wife's ML, because I still don't have any wipers. :(

I did buy a complete wiper assembly on eBay, and prior to installation I tested it by applying 12V, and watching it work, so I removed the old assembly, put the new one in, and... nothing! Same clicking as before coming from the relays, no movement. I even tried it without the wiper arms to make sure it had nothing to do with binding or anything, but no happy ending.

So I honestly have no idea where to even start. My mechanic suggests I replace the EIS, because he feels it's still the likely culprit, but he can't guarantee it will fix the problem, so spending a grand or more on a "possible" solution without any guarantee of success, is not something I look forward to. So for now, I;'m only using the car on dry days.
 
#12 ·
One R230 owner's experience here: new EIS will likely solve your problem.

The symptoms I had when my EIS failed:
Wipers would not work
Rollbar would not work
Maybe some other stuff ... it was two years ago, and I forget the details

The new EIS made all those problems go away, and they've stayed away. But things shouldn't be so complex, so interconnected, so difficult to diagnose, so expensive to cure.

Good luck, Mate. Let us know how you get this resolved.
 
#13 ·
This past week I handed the car to my mechanic, and told him to fix the wipers. I expected a $1K repair bill, because I expected the EIS needing replacement, but in the end, it turned out that the issue was a lot simpler to fix.

As I previously mentioned, when I pulled the wiper motor wires out of the socket in the fuse box, I was able to measure proper voltage, yet the when the motor would be plugged in, I'd just get a lot of chattering from the relays. Armed with that information, and the fact that everything else on the EIS is functioning correctly, the mechanic started to think along other lines, that the EIS might not be the source of the problem.

He pulled the wiring from the steering wheel/multi-function switch, SAM, etc, and started tracing everything. It turns out the problem was some wires that were frayed where the connectors are crimped. When subjected to a load, they could not handle the current, which dropped the voltage and cause the relays to fail to actuate. The wires were replaced, and my wipers are finally working.

Total cost for all the labor (no parts other than some wires), $350.

All things considered, I'm a happy camper now.
 
#15 ·
I agree with Heatwave on the value of the mechanic! It's rare to find one that will trace wiring like that. Most would have started with the EIS and kept on going until the SAM, wiper motor and two other wiring harness were replaced.
 
#16 ·
Yes, he's a good man. He's been doing work on my cars for the last 8 years.

In fact he's the one that fixed my EIS the first time around when I was having issues just like Heatwave, except he actually took the EIS apart and cleaned the contacts and everything and it's been working fine ever since.

So Yes, I wholeheartedly agree that he deserves a nice bottle of booze (although I'm not sure what kind he likes :) )
 
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