W126 Installation Headlight Washers/wipers

[GNJ]

I have a 1983 500SEL (LHD) and hav just acquired most of a 1989 560SEL (RHD) for its leather interior. I thought I would also install the headlight washer/wiper system whilst I was at it. I have now installed the system, but the wipers are not working nor is the washer pump.
I have taken all the wires, including the relay, from the donor car - by slicing open the looms and taking exactly the wires that were connected to the wipers, washer pump and relay - and installed them to the same wiring setup. I am attaching a diagram showing the wiring as installed.
If I understand this correctly, then the headlight washers/wipers should activate when the windscreen washers are activated PROVIDED THAT the relay allows the circuit to be completed. This depends on what the lead 'A' is connected to. On the donor car it appeared to be connected to the rotary light switch at the contact for the sidelights, so once the sidelights are on, the relay will allow the headlight wiper circuits to be completed which, in turn, will complete the headlight washer circuit.
I have tried connecting lead 'A' to the sidelight at the back of the headlight unit, just for testing purposes, but I do not seem to be getting a current. Nor are the headlight washer/wipers working.
So:
1. Does the circuit seem to be ok? (It does appear to be exactly as it was in the donor car).
2. Where is the best place to connect 'A'?
3. Any other ideas?

I will be very grateful for any help with this - electrics are not my strong point!! Thanks.
Gavin

 

[Myros]

Sounds obvious

but was it all working before the transplant?

You can just put 12 v across the washer pump and check it works,and you will find it a bit more difficult to test the wiper motor, as if it's anything like my 107, it's all well sealed up and not easy to strip. You should still be able to pass some voltage into the relevant wires though.

 

[GNJ]

Good point! I have now checked the washer pump and both the wiper motors - all working.
Any suggestions for the next step?
Thanks

 

[Myros]

what about the fusing?

has the extra load blown the fuse? The wiring diagram seems ok to my simplistic eye. Unless you need another relay to feed the wiper motors and washer pump?

 

[GNJ]

The fuses appear to be ok. If you think the wiring diagram looks ok (I agree, the logic appears to be good), then I think I will try attaching the wire 'A' to different feeds to see if I can get life! I don't think it should need an additional relay - I have installed the additional relay from the donor car and one should be enough I would have thought. I'll try the different feeds tomorrow and post my results.
Fingers crossed!
Thanks for your input - it always helps to have an independent opinion.
Gavin

 

[Dec]

Hi Gavin,
How are the headlamp wipers turned on, is there a separate switch, independent of the windscreen wiper switch?
Or
Are the headlamp wiper motors turned on when the windscreen wiper is turned on? If this is the case then the windscreen wiper motor wiring is missing from the diagram.

Without numbers, the relay wiring doesn’t make any sense as the coil is not identified….see http://www.the12volt.com/relays/relays.asp


Dec

 

[GNJ]

Hi Dec,
The headlight washers/wipers are actuated from the windscreen washer/wiper stalk. There is not a separate switch. When the stalk is pushed in the windscreen washers are activated and the windscreen wipers wipe 4 or 5 times (this is standard and is currently working). Having added the headlight wash/wipe system, my understanding is that by pushing in the stalk then the circuit for the wash/wipe system is completed and the washers/wipers should work PROVIDED THAT the headlights are on - hence the need for the relay. If the headlights are not on then the relay will not allow the circuit to be completed but if they ARE on, then the relay will allow the circuit to be completed. Does this sound right?
I will check through the link that you sent me and then add the necessary info to the wiring diagram.
Thanks for your help
Gavin

 

[Dec]

Hi Gavin

The existing windscreen wiper set up in your car may not be wired up or suited to allow for the addition of the headlamp wiper system, maybe the windscreen wiper motor and the stalk in the donor car is somehow different from your car.

In a way you only have halve the system, the other halve is still in the donor car, in the form of the windscreen wiper motor, stalk and a relay connected to the lighting system. When the headlights are off, then you don’t need to wash/wipe them so a relay controlled by the headlights dose sound right.

The only thing I would suggest, if it were possible, is to go back to the donor car to see exactly where wire A in your diagram is connected, and maybe, if you are wealthy, you could buy the wiper motor and stalk as well.

If you don’t have any success, you could wire the headlamp wiper system completely independent of the windscreen wiper system and use a push button switch to operate the headlamp wipers and pump.

I think you probably want to get the car into an “original” state but unless you can crack the current problem, then this is the only other option that I can see.
Let us know how you get on.

Dec

 

[GNJ]

System Now Working

Thanks to all of you for your helpful input. Having left it alone for a couple of weeks, I have now got the system working.
I rechecked the wiring diagram and drew the wiring for the windscreen wash/wipe system as you suggested. This made it very easy to see where the last connection (labelled "A" in my diagram) should be made. I made the connection to fuse No. 1 in the fusebox and the system works! And it works from the stalk on the steering column, as it should.

Some points, if anyone else is thinking of doing this:
1. The system came from a 1989 car, which has much more advanced electronics. The headlamp wash/wipe system should only operate every fifth time that the windscreen washers are used WHEN the headlights are on. The system as installed on my 1983 car operates each time the windscreen washers are used when the headlights are on.
2. The 1989 car has a slightly different front end to the chassis, which meant that the brackets for the wipers needed to be straightened and rebent so that they are approximately 2 cm shorter. The wipers now fit neatly behind the small panel underneath the headlight.
3. From the donor car I took:
a. The small body panels underneath the headlights, together with the clips that hold the water tubes and the grommets through which the wiper spindles pass.
b. The two wiper motors, including brackets.
c. The wiring, complete with the relay.
d. The second water pump, together with the inline connector that sits on top of the windscreen washer pump.
e. The pipes to supply the headlight washers.
4. I drilled out the existing washbottle to take the second washer pump.
5. I did not need to modify the existing wiring at all - just install the additional wiring.

I am attaching a photo of the modified bracket for the wiper motor, and an updated wiring diagram.

Thanks to all once again.

 

[gaunty]

I read this post with interest. I have a 1989 r107 whose headlamp wash / wipe system does not work. I have previously been advised on this and other forums that it is almost certainly down to corrosion and mechanical problems with the system - however, I still hold a belief that it is worth investigating the electrics as the pump operates when fed independently - so I think the relay that senses that the lights are on MAY be the problem.

My question is - where do I find this confounded relay in the car ? Do you remember ?

 

[Dec]

The below diagram refers to Fuse Relay Box (behind right kick panel)
http://www.autolib.diakom.ru/CAR/Mercedes-Benz/1989/560SL/SYSTEM WIRING DIAGRAMS/3413.pdf
http://www.autolib.diakom.ru/CAR/Mercedes-Benz/1989/560SL/SYSTEM WIRING DIAGRAMS/

Dec

 

[GNJ]

Where is the relay?

It is a long while since I did this! The only other relevant picture I took at the time is attached.
The relays and fuses are mounted together in a box inside the engine compartment up against the bulkhead. I do know that the relay was in that box, but I cannot remember now which relay it was.
I am away from home at the moment, so cannot check the car. I will be able to check it on about the 15th May, so if you still haven't located it by then send me a message and I will take some pictures for you.
Best Regards
Gavin