Alan

Folks,
Looking for some other opinions here. I've been thinking about the intermittent wiper design on the 928 and I'm frankly surprised Porsche didn't come up with something better.

I find my intermittent wipers to be one of the least well thought out of the major driver controls. It seems like such a basic system. I find I can never easily locate the "rate control" since I can't see it behind the steering wheel, and when I do I never know which way I need to move it for faster/slower and it takes a while to see what the effect is and get it set approximately correctly. Then adapting to changes in conditions starts this all over again... The range of control is also a pain - mine ranges from 4 secs to about 20 sec I'd like to have more range at both ends of this.

Do any other Porsches (up to current) have a better system ? digital control? (this would seem easy enough and so much more intuitive) maybe even automatic sensing of visibility impairment for rate...?

Heck I'm from Arizona - its not like I need the thing much - but it intrigues me that these controls don't seem to live up to the ergonomics & simplicity of the other major controls (e.g. the Cruise Control - I consider this fantastic simplicity & great ergonomics combined).

Is there some wierd legal reason? Did Porsche eventually engineer a great system on the 911's?
Am I missing something? maybe every one else thinks they work great?

Anyone done anything to modify this?

Alan

PS I think the rest of the wiper controls on my GTS are absolutely great - which just makes the intermittent feature seem so much more lame to me...

Nicole

Remember, the car was initially designed in the early 70ies. Many things we take for granted nowadays were considered really high tech at the time. I don't know, if the 928 came with this feature from the beginning, but integrating unexpected stuff is always a challenge. On your GTS you already have the improved version - the pre-airbag cars had a little adjustment wheel UNDER the dash pod. THAT looked like home made with parts from the electronics store...

Randy V

Alan, you have far too much spare time on your hands. Have you considered doing volunteer work <img src="graemlins/roflmao.gif" border="0" alt="[hiha]" /> ?

Alan

Randy,
You are probably right... but I might just keep thinking about this anyway.

...my quest for the perfect car, started out pretty good already...

Alan.

Normy

My thoughts too, Alan...

I think these cars were designed by people who enjoyed driving more than anything else; the dynamics of the car are incredible, but things like sunroof mechanisms, cruise control brains, door locks, ALARMS, window regulators, and a few other items appeared to be of second interest...and overall were pretty average quality.

My last car was a VW Corrado, and it had a deal where you could adjust the wiper delay by turning on the wipers, then turning them off for a certain period of seconds, and then back on. The relay recorded the off time and that was your new wiper delay. I have had the idea to look at the wiper relays on my car and a VW and see if they are interchangable. Haven't had the chance yet...

Normy!

Rob from NH 87 S4

I'm with you Alan... this is a weak spot on my 87-S4. I've noticed it as well. I try to not to drive my car in inclement weather of any type (yes, she's a bit of a garage queen) - so it is of no great consequence to me. However, details like this, when omitted, are significant given the excellence of the vehicle in so many other areas. <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />

Alan

Normy,
What you described is very similar to what I had in mind...Flip the switch to select intermittent mode - it wipes & sets the interval to maximum time, wait until you need to wipe the screen again pull a stalk to set the repeat interval. If you later need it to repeat faster just pull the stalk when you need - voila new repeat interval set. Need a longer delay - push a stalk to reset to max interval & start all over.

This would be so intuitive to use & immediately precise on timing & adjustment. The control functions would be kind of analagous to the Cruise Control operation.

Only question is how hard would this be to retrofit ...Uggh (we all know the answer to that!)

Alan (still dreaming about it...)

Normy

Alan-

I think...that the intermittent wiper on Corrados is controlled completely by the wiper relay. I think...

-As I say, I'd love to have acces to a modern VW relay so that I could check the pins to see if they are the same pattern as our relays. If so, I guess I'd plug it in and see what happens. I don't have access to one of these relays right now, but I've got my eye open.

Anyone here have a recent model VW?

Normy-

Dave H.

i have the intermittant relay in my Jetta. i too have been thinking of looking at the wiring to see if the VW relay could be used. prob'ly have to bypass the pod wheel though. if the wiring is close it should be able to be made to work. it's all in the relay and it being swithed on/off. the timer's in the relay...

hmm, think i'll go up to the garage...

Eric Dvorak

My 88' BMW 750iL also has the wipers you set by pulling the stalk at the intervals you want, I don't know about VW but BMW has a control module for their's (this car has modules for everything). My point is that the more complex the systems, the more complex the problem. This past January on a trip home from NYC at night during a snow/ slush storm that module took a dump making the drive a nightmare, at that time I would have rather had the simple system.

Not a sermon, just an opinion.

Alan

Eric,
Actually I've been looking at the wiring diags for the system on my GTS. The intermittent is contained in a single 'relay' module but all the regular wiper functions - Wipe, Wipe1, Wipe2, Wipe3 & Wash are direct drive from the switchgear. So on a 928 (I'm guessing its similar for all yrs) if the intermittent module goes out you still have all the basic functionality retained (a fuse could still bite you).

In any retrofit you'd obviously want to retain this for exactly the reason you state. No matter how good a driver or car its a pretty humbling (terminal..) experience to not be able to see through the windshield at speed.

Anyway I will contine to investigate but I doubt we will find a simple drop in solution for this. Apart from anything else all the existing stalk controls for the wipers already do something in every position...

Alan

Nicole

On my Dad's 528i, the wipers slow down when you stop at a traffic light. I think they do some more tricks, but I forgot.

I think there was even a car that turned on the rear wiper, if the fronts were on and the transmission was put in reverse.

Dave H.

well i pulled the relays out of both cars (88 S4/96 Jetta) and there are two differences just on the relays. one good, one maybe bad...

the porsche relay has 7 pins, the vw has 6. this doesn't look bad at first because the pin the vw relay is missing is pin "R", which is the pin the porsche relay gets it's signal from on the interval pot in the pod, so installing the vw relay would automatically bypass the pot. that's the good news.

the maybe bad news is that the wire diagram shows pin 15 ( key on 12v ) on the porsche relay only goes to the hot side of the actuating coil, but on the relay itself it goes to the coil switch contacts and the "brain" ( for lack of a better word ), so there's some inconsistency between the two. the vw diagram ( and relay ) shows it going to both also. i think the porsche diagram is drawn wrong.

so i'm thinking what it might come down to is someone with the vw relay just trying it, because if the wire diagram is wrong and the relay diagram is correct, it should work. they both do the same thing, i can't see why they would redesign a curcuit they've used for years before that. ( but then, i did electrical troubleshooting at Boeing, so i've seen some weird ****e... )

i may plug in my factory vw relay just to see if it works, then maybe try the programmable relay...

so who's up for it?

Alan

Nicole: Damn it! - now you've got me thinking about the rear wiper (and I'm not very impressed with that one either).

Pretty cool idea you mentioned though - auto rear wipe in reverse, ummm

I like the idea of speed sensitivity to the intermittent rate too...

This is the stuff Porsche should have been thinking about 10+ years ago.

Dave: I'd be careful to check out the relay equivalency fairly well first, so there is no chance of damage - other than that we are all 100% behind you... can't wait to hear the outcome.

Any idea what the ~cost of a VW module is - just in case it works!

Alan

Max

Alan,
A simple solution would be to find a potentiometer with a larger range. It is the potentiometer that controls the time for the relay.

David R,
Could you scribble out a diagram of the VW relay (MS paint brush will work) or a scan of the VW wire diagram and then send it to me. I would like to see it first hand. I can't help but wonder where the VW switch signal comes from?

All,
I like the idea of the VW relay with its programmable IC to drive the intermittent wiper function. Being that the stalk functions are all used up on 89-up 928’s, one could remove the factory wiper potentiometer and install a small momentary switch in it’s place and use the factory run wire to CCP.

Just an idea, the relay could be remote mounted with jumper wires from the factory relay location on the CCP.


Kindest, regards

Max