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Posted by: Geezer914 Feb 23 2023, 01:27 PM

72 in South Jersey, so I took the Porsche out of hibernation and went for a drive. Over the winter I installed an intermittent wiper relay with the factory harness. As I am driving, the wipers kept turning on no matter what the position the switch was in. I stopped and pulled the relay and the wipers worked normal on hi & low and stayed off with the switch in the off position. How do I test this relay?

Posted by: jim_hoyland Feb 23 2023, 03:29 PM

Possible grounding up intheswitch ? I never experienced what your IW does; but, I do get ghost wipes occasionally. The consensus is the the with has a loose or faulty ground.

Posted by: Geezer914 Feb 23 2023, 03:45 PM

After I pulled the intermittent relay, the wipers did not come on again. If I activated the wiper switch. they worked in the low and hi position. So I think that would rule out the wiper switch. I double checked the wiring according to Bowlsby's library and everything checks out. I just have to figure out how to test this relay with a 9 volt battery.

Posted by: 914Sixer Feb 23 2023, 08:50 PM

URO reproductions available for around $20. Have rarely seen a bad relay, but it happens. Check grounding screw in steering column.

Posted by: jim_hoyland Feb 24 2023, 02:31 PM

What happens when you move the wiper switch down from the off position that would be the intermittent mode.

Posted by: Superhawk996 Feb 24 2023, 03:25 PM

The smart in me wants to say the schematic for the relay is right there - printed on the side

Trying to be more helpful. . .

I think you will need 12v battery - don’t assume 9v will do it. May not be enough current to drive the solenoid and/or timer internal to the relay

Looking at schematic for vehicle

31 - ground
15 - 12v power into the relay
53s & 53m are the relay contact - leave pin 53s disconnected. Monitor pin 53m with voltmeter - should alternate between 12v and 0v as relay clicks
S - this is the ground coming though the wiper switch that triggers intermittent relay to ON - that ground is noted in black line with arrow on the attached photo

Posted by: r_towle Feb 24 2023, 03:33 PM

Curious,

What makes it intermittent? Heat?
Meaning how does it not come on at a regular frequency?

Posted by: jim_hoyland Feb 24 2023, 03:49 PM

You saw Sir. Andys thread ?
http://www.914world.com/bbs2/index.php?showtopic=2094

Posted by: dr914@autoatlanta.com Feb 24 2023, 04:25 PM

not the relay one of the screws that holds in the switches is loose and not making a ground

Posted by: Superhawk996 Feb 24 2023, 08:27 PM

Let me 1st say I’ve never taken one of these relays apart.

Based on the schematic in the factory manual that shows a transistor symbol and the relay that shows a square wave, I’m going to guess it’s some sort of astable flip flop circuit with timing controlled by a resistor-capacitor circuit. That flip flop circuit then Triggers the solenoid on either the high pulse or the low pulse. Based on the schematic on the relay - I’m going to guess it triggers on the high pulse . It will trigger on a steady frequency. Intermittent in the sense of 1970s technology - not variable frequency like todays intermittent wipers.

As stated - if someone has dissected one and I’m wrong - please correct me.

@“r_towle”.

Posted by: Geezer914 Feb 25 2023, 08:49 AM

Pulled the steering wheel, wiper switch screws were tight. If the screws were loose preventing a good ground, then the wipers would have been acting up before I installed the intermittent relay.

Ordered a new relay.

Posted by: Superhawk996 Feb 25 2023, 12:39 PM

What? You’re not even going to test the old one?

Posted by: Front yard mechanic Feb 25 2023, 01:58 PM

Only use the relay when it’s raining

Posted by: 76-914 May 12 2024, 07:04 PM

Just saw this........a little too late maybe. Anyway, I went down this road last week. Look at the backside where the wires enter the socket for the relay. If the brown wire gets pushed out of its nest in the socket you will be able to. see the very end of the non-insulated crimp terminal. Symptoms are exactly what you described above.

Posted by: jim_hoyland May 14 2024, 04:21 PM

It would be nice if there was a test procedure to verify the relay is in good order. I previously wrote a test procedure for the L-Jet dual relay, but never got far with the intermittent relay.

Posted by: Bartlett 914 May 14 2024, 04:26 PM

I agree. Tighten the wiper switch mounting screws in the steering wheel.