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?

Click to view attachment

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.

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.

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

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

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

Click to view attachment

Curious,

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

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

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

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”.

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.

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

Only use the relay when it’s raining