'73 T wiper function questions

[911hillclimber]

Judging by the silence nobody knows any more than I about this!

Having now blown 4 x 16A fuses and down to my last one, I'm no farther forwards, but if someone is reading this tale:

The relay is in the car and rigged-up to test.
There are certain connections that have been tried:
1
Relay pin 3 (12v to motor) to Bk/Yl on the motor (53b on the motor) results in a part wiper move responding to 5 secs on the relay and then stops and blows the car's 16A fuse.
2
Replay pin 3 to Bk/Purple on the motor (53 on the motor) results in no movement, the replay clicks every 5 secs, 16A fuse intact.

Note!
I have assumed relay pin 5 is connected to motor earth
Relay pin 4 is 12V in and 16A fused, measures 12.9volts.

I have tried the wiper with relay pin 3 wire on Bk/yel and Bk/Pup, results as above.

If i return the car to normal connections to Bk/purp & Bk/yel then the wipers/washer all work correctly.

Can't help but surmise that I have relay pin 3 going to the wrong motor connection, but now out of fuses will have to wait until I get more.

ANY suggestions welcome, starting to loose enthusiasm forthismod!

img upload

[AndrewSlater]

Hi Graham, OK I will bite and try to help.

I must admit on your earlier posts, I briefly looked into this and thought to myself 'I'm not sure that relay is going to work for you' - but thought I would bide my time to see if it did work.

Firstly the wiring diagrams I have for a '72 car are really awfully drawn, in that the symbols for both the wiper motor and the wiper switch aren't terribly clear as to function.
The wiper switch symbol (item 30) includes the flasher, dimmer, wiper/washer switch and the horn function - so it is all a bit of a muddle to distinguish.
The wiper motor symbol includes the parking mechanism but again it is badly drawn.

Secondly the info from 12planet is also pretty poor and a little self contradicting. It talks about an output from the relay 'Incorporates an output for supplying +12V to the wiper motor park switch which shorts the motor at the end of the wipe cycle, bringing the blades to an immediate stop in the 'park' position' - but it is not clear which one they mean.

I suspect that you are firing the relay for 5 seconds which is in turn closing the relay between pins 3 and 4 energising the motor, however at the end of the 5 seconds, the wiper is in a position where it continues to self park, so the motor is still energised for a period. Unfortunately at this point the relay opens and pins 3 and 5 are now shorted, shorting your self park motor feed to earth and blowing your fuse.
All of the above is clearly conjecture as 12planet don't show the internals of their relay or really anywhere near enough info to be confident in any of this.

If you wanted to gamble your last fuse - you could disconnect pin 5 of the relay and see whether it then works correctly.

Hope some of this helps.

My gut feeling is that the self park on the Porsche wiper motor is a little different to other systems out there and this relay isn't that suited - but lets hope I am wrong.

Good luck
Andrew

[911hillclimber]

Thank you Andrew.
The diagrams are tricky to relate too and sot what is doing what.
I've sent the same info to 12v planet, hope for some advice.
Since found 10 more 16A fuses and have 10 more ordered before I found them...
Will try your idea tomorrow and report back.
Thanks again.

[911hillclimber]

Can't wait that long!
Pulled pin 5, no action, fuse survived, relay not clicking.

[AndrewSlater]

That's a shame.

I suspect the relay requires a permanent ground at pin 5 in order for the onboard timer circuitry to run.

Oh well I tried

[911hillclimber]

Yes, worth the try indeed.
In this relay, there are just 2 wires to place, pin 3 and pin 5.
There is one ground on the motor, and I feel that where pin 5 goes, but as a parking motor the diagram of the relay seems to me to place 5 to motor ground.
That leaves pin 3 to place on either bk/yellow or black/purple, one of those blows a fuse after 1/2 a wipe, other does nothing, keeps the fuse and the relay ticks...

I am beginning to think this relay is not right for this 911!

[SeanP]

Looking at a 71 wiring diagram here so don’t shoot the messenger!

Have been playing about with a 1969 wiring loom and I know this much.
If the wiper motor is stopped and the park connection is made and has voltage on it then the motor parks.
If you stop the motor and you don’t have 12v on the park contact then the motor stays where it is. If you then apply voltage to the park contact it parks!

Pin53a is the constant voltage to the park contact. It’s always live and applies a voltage to the motor via a cam operating a contact.

Pin 53 is the full speed wiper

Pin 53b is the middle speed

Pin 53e is the low speed

The relay you have bought is a simple timer relay with some bridging from the 12V in to the 12V timer circuit. This is set to operate for 5 seconds moving the wipers away from the park position thus forcing the wipers to park.

Piggy back the wire from pin3 on the relay onto terminal 53 on the wiper motor. I.E so it not in series with the existing circuit but in parallel, (Both feeds can operate the circuit, acting as a logic or gate)
Do not connect terminal 5 of the relay.
Pin 2 of the relay is acting as a switched ground, (your new switch), to enable the timer circuit of the relay
Pin 4 needs to be connected to a permanent fused live.
If you get no movement from the motor move the piggybacked wire to either 53b or 53e.

[SeanP]

Pin 5 on the relay will switch your fused 12V supply directly to ground if connected to groundhence blowing the fuse. Its a timer changeover relay.

[911hillclimber]

Excellent!
Thank you, will try that tomorrow.

[AndrewSlater]

Thanks to Sean for the clearer explanation.

Graham as already said that connection to pin 53 causes no movement but 53b does .
I've already suggested that he disconnect the ground from pin 5 as it is shorting the motor feed.
He said the relay no longer fired when the ground was disconnected, but I'm guessing he hadn't linked relay pin 3 back to 53b (the connection which gave wiper movement).

So it would appear that if you connect pin 3 to 53b and disconnect the ground from relay pin 5 it should all work.
Good luck

[911hillclimber]

Yes, dead right!
Car all back together now but not without some 'observations'...

Pin 5 off
Pin 3 to 53b (Black/yellow dot and intermittent works. Putting pin3 on 53 did nothing, no clicking relay, no movement but fuse held.

The parking then became a bit of an issue!

The wiper so wired parks in a different place, oddly exactly one spline away on the wiper arm's original position, further up the screen, right in driving line of sight.
This exact position is influenced by the water on the screen and the fact I oiled the wiper motor link pivots, first time in 50 years (1973 car).
This loosened the wiper action a touch.

Re-mounted the arms to get the arms closer to the base of the screen and found the two blades fouled by 3 to 5mm, enough occasionally to get an 'end to end' conflict resulting in a bit of an interference so had to reposition the blade/arm location attachment on the drivers blade. Easy to do, but a bit of messing about.

However!

All back together, air box was the usual fight but I won.

Just need my latching dash switch now with 'period' black knob (similar to the factory rear de-mist switch) and tuck it all back behind the fuel gauge dial.

Thank you to Andrew and Sean for stepping in to help me out.
I have never liked car electrics, working behind dash boards and all the wires and connections.

I now feel it was all worth it of course, and I have a LOT of 16A fuses.

Here is the wiring diagram if anyone else cares to have a go:

wallpaper titanfall 2

[SeanP]

Good news!
Glad it all worked in the end!

I did say that I was working with a 71 wiring diagram and a 1969 wiper motor!
Porsche wiring diagrams have never been the clearest!
You should try following a 69 wiring diagram and find how far away it is from the reality of the loom in the car! Laugh a minute ! And I am a controls engineer by trade!

[AndrewSlater]

Great news - well done!!

[911hillclimber]

Thanks both.

The Haynes diagrams are all I have and you find the steering column stalks are in fact cut into left and right on 2 diagrams but the diagram says one lever does the worth of all functions.

I am always surprised how many leads are not connected on the loom and will not stretch to any location either, but so glad it is all done and have a result too.

[deano]

Great job, and thanks for posting the finished solution!