Mystery electrical component and wires -74 911

[jjs3rd914]

Newly purchased 1974 911. Found this device attached by sheet metal screw under the dash radio speaker. One black wire comes from it which was not connected to anything. Component says, Beru FK 220/301 and in small print .47 micro-F (farads?). Believe it is a resistor/capacitor device but for what. Also in the area under speaker found a red with white stripe wire not connected to anything.

Could this has something to do with the intermittent wiper setup which this car has (which does not work)? On the plug to the wiper motor, there is a dual spade connector that has a red/white attached to one side and nothing to the other. My factory shop manual wiring diagram does not show wiring for intermittent wipers. We wonder if the loose red/white wire attaches to the device and the black wire from the device goes to the extra terminal on the wiper motor, which is not clear on the last photo. That extra terminal is to the left red/white wire in the last photo center to the wiper motor connector block.

Anyone know what this is and where these wire go?

Thanks

Jeff

[warner53]

I really have no idea......but would suggest

a tracking device.....cia

sorry I could not resist.

W

[Driver_X]

Here is a picture of my '74. There should be another red/white wire connected there.

[jjs3rd914]

Driver_X

Thanks for the reply. Your photo shows that is where my unattached red wire might go. However, does your car have factory three speed wipers with the intermittent option? If it does then we are at a loss of what the mystery device is. If it does not, maybe the device goes in between as we suggested in original post as we have no other explanation as to what this component does or where it was attached.

I have done a google search and cannot find a description of what the device might be. Any electrical experts have an opinion on something that says .47microF and what they are used for? The black wire coming from the device is fairly thick, so it must meant to carry some juice.

Thanks again

Jeff

[kodioneill]

It is a capacitor but for what I don't know. Possibly radio suppression or wiper delay.

[Grady Clay]

Jeff,

The 0.47 μF device is a capacitor.
These are typically used for radio noise suppression.
If there is a spare terminal at the power for the wipers, I suspect the wire belongs connected there.
(Connecting this to power or anything else will not effect the operation of that device.)


Looking at the ’74 wiring diagram, I only find four red/white wires.
We can eliminate the one in the engine compartment for the heated rear window.

The other three are for your hazard warning system (4-way flashers), headlight flasher and the ‘park’ circuit for your wipers.
Do your wipers park correctly?
Do your 4-way flashers work?
Do your headlights ‘flash’?


Put a test light on the loose red/white wire and report if/when it gets 12 V power.
If you get 12 V power all the time, remove the fuse S13 and see if power is removed.


Is the unconnected terminal here (red arrow immediately below)?




The connections at your wiper motor are labeled.
They may be difficult to read but they are there.
They are numbered with wire colors:
53i = green
53b = black/green
53 = black/violet
53e = blue
53a = red/white
31 = brown

The red/white wire goes to the ‘cold side’ of fuse S13.
The wiring diagram (p. 0.1 – 3.3) shows this fuse terminal also has another red/white wire that goes to the wiper switch.

The image from Pelican Driver_X shows two red/white wires at the wiper terminal (53a?) (red arrows ‘1’ and ‘2’ immediately below).
The terminal numbers are raised on the plastic piece (blue arrow).






Here are the images from my ’74 911S:
Note there is a single red/white wire at wiper terminal 53a (red arrow below).




There are two red/white wires (as the diagram indicates) at the fuse S13 (6th from left) (yellow arrows).


(sorry about poor focus )



I hope this helps.

Best,
Grady

[jjs3rd914]

Grady Clay

Great reply-Thanks

The unattached red wire is hot with ignition on. There is no power at the wiper connection 53a with ignition on or off. I suspect that Grady Clay's 911 does not have the intermittent wiper option while Driver_X's does. I checked the wiring diagram for a 75 911 with intermittent wipers in shop manual and it does show two red wires at 53a, but not any device like I have. Also the 75 diagram shows a wiper relay which I cannot find yet. Anyone know where that is? For some reason the 74 wiring diagram does not reference intermittent wipers.

To answer Grady Clay's questions - wipers do not park, they just stop when I turn off stalk switch. All the speeds work but not the intermittent. I know there could be other reasons for this behavior at the steering wheel.

4 way flashers and headlight flash work.

The mystery device sure looks like it was stock. Some where along the line it got disconnected. Perhaps the capacitor as suggested might have been added for some suppression/filter reasons when intermittent wiper function is used.

So it does appear the red/white wire should be connected to terminal 53a at the wiper. The question is can the device be connected in series with out frying the wiring and/or wiper motor.

Again you electrical wizards, does having such a device in series serve any purpose?

Thanks to a great forum!!

Jeff

[Driver_X]

Yes, I have intermittant wipers & 3 speeds. However, I believe my current switch is bad and I currently have no low speed, park or intermittant function. But, when I was replacing my wiper motor (reason for the pics) I tested it before I put it all together and I swear I had all functions working properly, but I was also using a 2nd switch that when I get a chance, I will plug in again and see if I can regain all function. But I SWEAR all functions were working regardless of which switch I was using which is why I didn't bother replacing the switch. But maybe I was wrong and got confused....

[jjs3rd914]

Tomorrow we will hook up the red/white wire to the wiper connector and see what happens, that is if we get intermittent function back. The reason I found all of this is we are putting back in a period correct radio. The PO had installed a Blaupunkt Montreal radio and that there must have been noise coming from the wiper relay, thus the filter was added. At least that is the thought. We will not re-install the filter unless things do not work or there is still interference noise from the wiper.

Is there agreement that the Beru device is a static filter?

We will post if things get working again.

Thanks

Jeff

[Walter_Middie]

Jeff,

My 75 has one of those, and I have intermittent wipers. Here are a couple of pictures to help, but taking pictures under the dash is difficult. First - the small black device has a black wire that is connected to the wipers. The black device is mounted under the corner of the dash speaker grill. The red/white wire is connected to the other side of the black device.



That black wire in the front goes to the black device.





Pay no attention to the modified red/white wire - I have used it to power an electric vest I use in the winter to keep warm on cold mornings.

[jjs3rd914]

Solved,

Thanks to all and to Walter_Middie for final verification yesterday. We installed the device in series and all seems to work now-well almost. We have located the wiper relay (right below the speaker) and hear it click, but no intermittent motion. When I push on the wiper switch on steering stalk they start to work. I have read other threads that there is wear in the wiper swith contacts which we will attend to later.

Again thanks for solving another 911 mystery.

Jeff
74 911
72 914
70 BMW 2800CS
64 Austin Healey 3000 in 6000 pieces

[Grady Clay]

Jeff,

I will speculate that the reason that the red/white wire was disconnected is the wiper mechanism is worn and the wipers keep going when you turn them off and they try to park.
This may be (or have been) under some conditions (temperature, rain, vibration) and not others.
It is wise to be prepared to remove the clock and re-disconnect the red/white wire if the wipers won’t park.


My desktop just decided to fritz and it is too early to call my IT guy.
Naturally, my scanner and software is on that and not on my laptop.

I’ll post both the ‘normal’ wiper current flow diagram and the ‘intermittent’ diagram when my desktop is back running.

While the Manual shows the ‘intermittent’ as a ’75 option, the same system was installed on ’74 models.
Porsche had a B&W additional (wiring or current flow) diagram for ’74 in a supplement.
I probably have that somewhere.

It might be useful to describe how to retrofit the intermittent wiper system to a 911 without that option.

Yes, the capacitor is for noise suppression.
It has no detrimental effect if you have one (or several) in the system.
If it (they) are not needed, it simplifies things to remove them.

Best,
Grady

[Walter_Middie]

The wiper switch consists of terminals # 53a, 53, 53b, 53i, 53e, and 53c. During wiper park cycle, 53e (blue wire) is connected to 53a (red/white wire, +12 v all the time). The connection is made when the wiper switch is off and the motor is not in the park position. The motor makes connection between 53e and 53a with an internal disk. The wiper switch connection between 53e and 53 puts the wipers into the slow mode, until the disk inside the motor turns to the park or off position. I cleaned the internal disk to restore wiper park.

53a Red/White = +12 v all the time
53a Black to a capacitor and a red/white = +12 v all the time
53 Red/Black = slow speed wipers
53b black/yellow = medium speed wipers
53i green = fast speed wipers
53e blue = park at slow speed
53c black = washer pump motor

Hope this helps - Rex