Hello,

I had this problem before , like 6 or 7 moths ago, where none of the above items worked. So I looked at the relays, checked the connections and after that it worked. Now i have the smae problem, but after i checked the relays, cleaned them and switched them around still they don't work. Actually sometimes they do work , but I can't seem to figure why sometimes they start working fine but and couple of hours later they don't anymore. they haven't worked now for 3 days at all. Not sure if i have to replace all the relays, or just one (are they connected in such way that if 1 doesn't work, the others don't either?) Also there seems to be 3 different type of relays in that box. But when i look at a part catalogue, there's one type of relays for the power windows and the seats, but a different type for the windshield wiper..... can anyone help me figuring this one out??

Thanks.

 

Forgot to mention, my MB is a 1986 300e.

 

Hi,
Trying to help but haven't got any info on your model to hand so bear with me if I state the obvious.

You have correctly recognised that there are different types....this is due to different contact types/ numbers (Normally Open vs Closed etc) and you have tried swapping them around.

How many relays are there in the box of the type used by the wiper circuit? 1 or many? (Many relays have their contact layout embossed or painted on them)

Based on the premise that it is unlikely that more than one relay would go bad at the same time, if there are more than one of the wiper type relay it is not likely to be the relay BUT could be a fault in the wiring/circuit board to which the relays are plugged. (e.g. associated disturbance).
On the other hand if there is only one relay of the wiper type then this relay may well be bad (burnt contacts likely). They are low cost STANDARD PARTs so try a new one. (It doesn't have to be a special MB part).

IF due to associated disturbance you need to look VERY carefully at all connections and especially if a wire has broken at the point at which it attaches to the circuit board/component. Dependent upon design the circuit board may also have a break in one of the copper strips.

Hope this helps. Sounds as though you are looking in exactly the right area.
Stuart

 

If they are all the same circuit some how you could have an interment short. another problem could be the fuse box wiring that the relay plugs into. I would check the fuse box wiring as well as the relays. Did the relays click when you checked them if no it’s the relay

 

Hi gus,

thanks for your replies.

Stuart, there are 3 types of relays in that box, this link shows them all. http://parts.autopartsonlinecanada.c...y=P&part=Relay

1 is a 5 pole terminal, i'ts black, plastic made cover and there's only one in the box.
there are 4 of the window regulator, seat adjuster relay ( made of aluminum) and there is 1 large black relay called the multifunction relay. this one is for the hazaed lights, heated rear window, and it says it's also for the wiper.

Here is where i have the problem, because the widonws + the seats + the wiper don't work, but they have dif relays and the wiper has a totally different realy than the windows and seats. Besides, the hazard lights work fine as does the heated rear window.

I didn't think of the wirirng to be honest, but wouldn't that affect the hazard lights too??

I looked at the fuse box infront of the relay box and all the fuses seem alright. Is there any other fuse box?

I'll check the wiring today.

Thanks again guys.

 

As I stated I don't have any diagrams or images of your vehicle in front of me.

I didn't notice that you stated that multiple circuits were NOT functioning. I only saw your bit about a different relay for the wiper.

If you have a multifunction relay then by definition if this is bad you will loose all associated circuits but you state that the hazards are controlled by the MF and these work.
Just thinking aloud....
How do you know that the MF controls the hazards other than the ad for a new relay?
How do you know one of the relays is specifically for the wipers on your car?

As the other post states do the relayS "click" when the ignition key is turned position 1 / 2. I believe they should. If not then the relay(s) or its coil supply is suspect.

In general multi function circuits of this nature can have multiple fuses. Potentially they can be on the relay power supply side, the relay operating coil side and on the relay consumer output side.

The power supply side fuse will be rated 30A or similar and protect the supply wiring to multiple relays. Problem with this scenario is that the hazards work. However it is possible that the MF has more than one power supply to it.

The coil supply for the seats is convenience controlled (door openetc), window lifts is ignition key position 1 controlled and rear window/ wipers ignition posn. 2 controlled. The hazard circuit is not ignition key controlled. This coil supply scenario sound possible. Don't know where the fuse is but could be inside the cabin / fascia / lighting switch area.

Each output may also be individually fused. The problem with this scenario is that multiple circuits have gone down at the same time.

You say the fuses "seem" OK. Have you tested them with a multimeter or similar?

If this doesn't resolve the problem you are back to a wiring / cuitboard issue.

NB. Be careful if you are looking at wires under the relay platform in case there is a loose / broken wire. If there is, then there is the possibility that this could earth or touch other leads with bad consequences if disturbed

Normal practice is to disconnect the battery. BE WARNED.

 

I actually don't know which relay is which or if the MF relay controls the wipers, except for that add. I ordered yesterday a repair manual so i'll wait for it in the next couple of days.

Yesterday when i got off work, went to the car and everything was working fine... It was a warm day but this morning everything went back to "not working". Not sure if it's related but in all the times that the windows, seats and wipers did work was after the car had been running for a while or when the temerature was warm, never when the car is cold.

If any of you guys find anything, I'd appreciate if you can post it.... as soon as I get the repair manual and hopefully figure out what's wrong I'll update you.

Thanks for all the help.

 

The ON/OFF nature of the problem associated with the WARM/COLD operating conditions points to a break in the power supply to the relays.
Did you check the fuses with a multimeter?

 

Yesterday I go tired of this problem and couldn't wait for the repair manual. So I rolled up my sleeves and took al the relays, fuses out and replaced the weak looking ones (fuses) cleand the relays again and checked all the connections. this morning everything seems to work fine (for now).

I don't know what exactly caused the problem but I guess the answer would be to check the entire relay and fuse boxes and the connections.

Stuart and Benz24, thanks a million mates. your suggestions and tips are much appreciated.

I found another problem now, it's very small but just wondering; about one of the window switches in the console and the mirrow switch, the lights that iluminate them from underneath don't work. I don't think they have a bulb, and they do work fine. But do i need to replace the switches or the ligths not working is a connection problem too??

 

Seems to confirm that the problem is in the immediate area that you have been working on.
Still think its due to poor connection possibly between contacts that are designed to permit replacement of parts. eg. Fuse cradle.
Maybe this time you have gotten the contacts clean enough etc to keep working for a significant time. Oxidation can cause an insulating layer to build up. Likewise heat build up tends to retemper metal and reduces pressure/grip to give good connection.

wrt your other problem.
...........don't work. I don't think they have a bulb, and they do work fine.
These sentences seem to be contrdictory!

Unfortunately I don't have knowledge/experience on parts this old. Suspect it is a different age related problem and will most probably be the bulb/LED that has gone bad.
Need to take switch apart to investigate and action accordingly or buy new component if the part is made in such away that you cannot gain access to the internals.
I believe switches of this vintage didn't have "customer" replaceable bulbs......but to a DIYer everything is possible!

Stuart