Two days ago, I tried to put 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 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 light go out, and the seatbelt works OK. All the other systems work fine, just not wipers.

I thought it might be the same issue as before, and 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.

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

 

This is what I plan on checking this weekend. I want to pull the harness off the motor and test the wires for voltage. I know there are 4 wires, but since I haven't opened it yet, I don't know what the color coding is, or what each wire is.

Do you have this information?

Assuming I do get a voltage reading, what is it supposed to be (range)?

If I don't see any voltages at the motor harness, what else should I look for?

And yes, the car does have the rain sensor.

 

The wiper switch signals firs go through the steering column controller and are then sent over the CAN to the left SAM which activates the relays to operate the wipers. This could be an issue in the steering column controller.

 

WDBSK75F05F104628

BTW, I did find the color coding for the connector, it's Red, Brown/Black or Brown/Blue, Green & Yellow. I also found the connection at the SAM (I think)

So now I need to know what each wire is (I assume red is 12V, but what about the others)

 

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

 

Or the relay

 

Unfortunately, it's not the relay.

I wish it was, as I have a complete replacement fuse/relay box fully populated (8 relays, 24 fuses), but the relay is good, I already tried replacing all 3 of the relay involved (A, G & H), and that didn't fix the wiper issue.

 

UPdate.

After much headache (trying to remove the windshield wiper cowling), I did manage to replace the the wiper assembly. Make a long story short, it didn't fix the problem.

The symptoms are the same. Whenever I turn on the wipers I get a fast clicking in the relays. When I pull the wiper wiring harness out of the socket (either at the fuse box or at the motor, the clicking stops.

So I have no idea what could be wrong. The relays are OK, the fuses are OK, the motor is OK (I tested it while off the car), the SAM is OK.

The only thing I can think of, once again, is the ignition switch.

Any ideas out there?

 

Dudeman: I had similar problems last year. Replaced the EIS module. Cured all the problems.

 

New here

 

 

No direct knowledge to share but see attached PDF's for WIS instructions.

Good luck,

Bob

 

 

 

Thanks Frederick but I fixed it a while ago. It turned out to be the wiper arm had seized. You should take yours apart and lube the two shafts it before it seize. It's going to happen. The center "shaft post" seized the outer one was ok, (the 3rd one is stationary no lube required it looks like).

 

+1 on replacing the EIS, it is defective, cleaning it won't fix it. I had the same many years back. There are older posts about this on this forum