Porsche 924 Scheiße - bizarre electrical problem, mystery solved...

17,448 · November 4

This all looks eerily familiar 😳

I'd need to check my thread but from memory it's something like the wiper motor and headlight motor are the same 🤔

6,396 · November 4

26 minutes ago, dome said:

This all looks eerily familiar 😳

I'd need to check my thread but from memory it's something like the wiper motor and headlight motor are the same 🤔

They're slightly different - I thought I had a spare wiper motor but turns out it's a headlamp one.

Anyhow, partial success. Wipers now work smoothly and swiftly, heater blower is quiet and gives all 3 speeds properly.

However, the weird intermittent glitch remains. Although I can now put my original intermittent relay in, and still have no intermittent whilst retaining self-parking. If I put the new relay in then I have intermittent even on the 'off' position. And it's not the switch - I've tried a replacement one of those.

Oh well.

29,372 · November 4

Bringing back PTSD type memories of trying to get the wipers on my XJ-S to work reliably...I think I must have had the damned motor out and back in the best part of a dozen times before I got the blasted thing to work properly!

I'm assuming this doesn't do the overcomplicated "run the motor backwards and use a totally different set of contacts to park the wipers" nonsense which seemed to be in there "because XJ-S things" factor that I had in play!

Do you have a schematic of the circuits involved to hand? Might be possible to trace it out and see if there's anything which leaps out as a likely cause. It sounds an odd fault, but with a schematic and figuring out the sequence of operations it should be possible to see where things are failing and to then point at likely causes.

November 4

2 hours ago, N Dentressangle said:

They're slightly different - I thought I had a spare wiper motor but turns out it's a headlamp one.

Anyhow, partial success. Wipers now work smoothly and swiftly, heater blower is quiet and gives all 3 speeds properly.

However, the weird intermittent glitch remains. Although I can now put my original intermittent relay in, and still have no intermittent whilst retaining self-parking. If I put the new relay in then I have intermittent even on the 'off' position. And it's not the switch - I've tried a replacement one of those.

Oh well.

I can't get the intermittent on my 944 working properly either - tried the relay as first option but no change, so was going to check the switch next

6,396 · November 4

18 minutes ago, Verysleepyboy said:

I can't get the intermittent on my 944 working properly either - tried the relay as first option but no change, so was going to check the switch next

Yeah, looking on the internet I don't think we're the only people with this issue.

Buggered if I can find out what it is though!

6,396 · November 4

1 hour ago, Zelandeth said:

Bringing back PTSD type memories of trying to get the wipers on my XJ-S to work reliably...I think I must have had the damned motor out and back in the best part of a dozen times before I got the blasted thing to work properly!

I'm assuming this doesn't do the overcomplicated "run the motor backwards and use a totally different set of contacts to park the wipers" nonsense which seemed to be in there "because XJ-S things" factor that I had in play!

Do you have a schematic of the circuits involved to hand? Might be possible to trace it out and see if there's anything which leaps out as a likely cause. It sounds an odd fault, but with a schematic and figuring out the sequence of operations it should be possible to see where things are failing and to then point at likely causes.

Here's a schematic:

Moving the column stalk to the “slow” position causes part B of the switch to feed power onto the wires coloured blue on the diagram, into terminal 53 of the wiper motor and out of terminal 31 from where it reaches earth via one of the crown of earth terminals behind the fusebox; the result is that the motor runs at slow speed. Moving the column switch to the “fast” position does almost the same thing, but this time part A of the switch feeds power onto the wires coloured green and into terminal 53b of the motor, causing it to run at high speed. You may have noticed that nothing so far has involved the relay, which doesn’t even need to be fitted or functional in order for the wipers to operate at either speed. That changes, however, when the rain stops and we turn the wipers off. The parking switch built into the motor now comes into play, and it connects terminals 53a and 31b on the motor together as long as the wipers are away from the parked position. This causes power to flow into the wires coloured orange on the diagram, through terminals 53S and 53M of the relay and into the wires coloured purple, through part B of the switch, onto the wires coloured blue and into the motor on terminal 53. The result is that the motor runs at the slow speed and keeps running until it reaches the parked position, when the switch opens and power is turned off, causing the motor to stop. Now we get to the really involved part! So far, the relay has done nothing but pass power straight through to allow the parking function to operate, and three of its pins have played no part in that process. Two of them are really only there to provide power and earth but the final one, labelled S, is what gives the system the ability to operate in intermittent mode and run the wipers while washing the screen. If you study the diagram, you will see that with the stalk in the “off”, “slow” or “fast” positions, part C of the switch provides an earth feed to part D. Assuming the washer switch is not being operated, this earth feed is passed onto pin S and the relay does nothing. If the stalk is moved into the “intermittent” position, however, pin S becomes disconnected. The electronic circuit inside the relay detects this and activates the relay contact, causing power to flow from pin 15 to pin 53M, through the purple coloured wires, part B of the switch, the blue coloured wires and into to pin 53 of the motor, which starts to run at slow speed. Very soon, however, the relay turns off again, which puts the system back into the parking mode described above. Power flows through the parking switch, the orange coloured wires, the relay, the purple coloured wires, part B of the switch and the blue coloured wires to continue to run the motor until the parking switch opens. As long as the column stalk remains in the “intermittent” position, this whole cycle will repeat every ten seconds or so. Finally, if the stalk is pulled back to activate the washers, two things happen. First, part E of the switch feeds power out of terminal 53c, through the fusebox and out to the washer pump, causing it to run as long as the stalk is held back. Secondly, power is fed through part D of the switch to terminal S of the relay, putting it into “wash/wipe” mode, where it closes, causing the wiper motor to run at slow speed in the same way as in intermittent mode. This time, however, the relay stays closed until the stalk has been released for a few seconds, and the system then goes back into parking mode.

Sadly I'm not clever enough to figure out what the problem could be 🤯

13,571 · November 4

I’ve got an intermittent intermittent problem with mine. Fine for ages then does all the randoms, usually when it’s hot and dry weather. So I look like I can’t operate basic controls.

13,571 · November 4

A good thing about yours is that blower motor. They changed them from a shitty expensive hard to find one you need to take the dash out to replace, for a universal VW one that costs about £25 and can be swapped out in 5mins, and you’ve done the difficult bit taking the shroud off. Yours and mine are both X reg, mine is the early one, yours is the later. So if it’s a bit noisy or crap just replace it.

November 5

15 hours ago, N Dentressangle said:

Here's a schematic:

Moving the column stalk to the “slow” position causes part B of the switch to feed power onto the wires coloured blue on the diagram, into terminal 53 of the wiper motor and out of terminal 31 from where it reaches earth via one of the crown of earth terminals behind the fusebox; the result is that the motor runs at slow speed. Moving the column switch to the “fast” position does almost the same thing, but this time part A of the switch feeds power onto the wires coloured green and into terminal 53b of the motor, causing it to run at high speed. You may have noticed that nothing so far has involved the relay, which doesn’t even need to be fitted or functional in order for the wipers to operate at either speed. That changes, however, when the rain stops and we turn the wipers off. The parking switch built into the motor now comes into play, and it connects terminals 53a and 31b on the motor together as long as the wipers are away from the parked position. This causes power to flow into the wires coloured orange on the diagram, through terminals 53S and 53M of the relay and into the wires coloured purple, through part B of the switch, onto the wires coloured blue and into the motor on terminal 53. The result is that the motor runs at the slow speed and keeps running until it reaches the parked position, when the switch opens and power is turned off, causing the motor to stop. Now we get to the really involved part! So far, the relay has done nothing but pass power straight through to allow the parking function to operate, and three of its pins have played no part in that process. Two of them are really only there to provide power and earth but the final one, labelled S, is what gives the system the ability to operate in intermittent mode and run the wipers while washing the screen. If you study the diagram, you will see that with the stalk in the “off”, “slow” or “fast” positions, part C of the switch provides an earth feed to part D. Assuming the washer switch is not being operated, this earth feed is passed onto pin S and the relay does nothing. If the stalk is moved into the “intermittent” position, however, pin S becomes disconnected. The electronic circuit inside the relay detects this and activates the relay contact, causing power to flow from pin 15 to pin 53M, through the purple coloured wires, part B of the switch, the blue coloured wires and into to pin 53 of the motor, which starts to run at slow speed. Very soon, however, the relay turns off again, which puts the system back into the parking mode described above. Power flows through the parking switch, the orange coloured wires, the relay, the purple coloured wires, part B of the switch and the blue coloured wires to continue to run the motor until the parking switch opens. As long as the column stalk remains in the “intermittent” position, this whole cycle will repeat every ten seconds or so. Finally, if the stalk is pulled back to activate the washers, two things happen. First, part E of the switch feeds power out of terminal 53c, through the fusebox and out to the washer pump, causing it to run as long as the stalk is held back. Secondly, power is fed through part D of the switch to terminal S of the relay, putting it into “wash/wipe” mode, where it closes, causing the wiper motor to run at slow speed in the same way as in intermittent mode. This time, however, the relay stays closed until the stalk has been released for a few seconds, and the system then goes back into parking mode.

Sadly I'm not clever enough to figure out what the problem could be 🤯

Honestly - I had read that about 5 times so far and it is astill as clear as mud why the intermittant wiper still doesn't work - think I need a couple of bottles of red wine downed before I read it again, might make more sense!!!

6,396 · November 5

Brilliant, isn't it? 🤣

November 5

21 minutes ago, N Dentressangle said:

Brilliant, isn't it? 🤣

Yeah - something like that....... 🤪

6,396 · November 5

Another 30 miles or so on the clock today, so hopefully it's bedding in a bit. Took it down to Berkeley and back:

So maybe some driving impressions are in order?

Firstly, I forget what twats people are around old cars. Someone pulled out in front of me on a roundabout today - the usual female, boomer incompetent Karen you get round here - and clearly didn't give a shit. I've put LED lights in the front sidelights so will probably just run with them on in future, as everyone else seems to have silly DRLs these days.

Otherwise it's all pretty good. It's not lacking in pace, and happily holds onto the tail of much newer BMW's and the like. I had a 1986 non-PAS 8v Mk2 Golf GTI about 30 years ago, and the driving experience is both similar and different. The 924 feels much lighter on its feet and better balanced (as it should do), and feels at least as fast to me. I suspect the Porsche is higher geared - it feels that way - and motorway speeds are definitely more relaxed on the revs and engine noise than the Golf was. Steering is lighter and feels more direct, and you can really sense the different road surfaces you're on - could be uncomfortable but actually it's more engaging and interesting at the moment. The ride is probably a touch firmer, but not uncomfortable, and the brakes are better I'd say. But then I remember Golf Mk2 brakes as being woeful. Bear in mind my 924 is on budget tyres, and could probably do with a front suspension refresh at some stage too. The driving position is also much more 'sporting', which takes some getting used to - you sit quite low, the dash feels high and you can't see the nose of the car unless the lights are popped up.

MoT will probably happen in the next couple of weeks unless it throws its toys out of the pram again, so I'll sort the mixture properly then. I did have a good length drive in it yesterday so popped a spark plug to see what the mixture was doing:

Not toooo bad, but obvs a little on the rich side. At least it's not actually sooty or oily.

Got down to Berkeley and thought I'd try leaning it off a hair and see what the plug said when I got the 10 miles or so home. Doesn't everyone travel with a long 3mm Allen key in their coat pocket? I leaned it off by probably 1/10 of a turn. That really is all you need on this. Just wave the Allen key at it and it'll shift: treat it like an SU and you'll be calling the big yellow taxi. Pulled the plug when I got home, and it's moving in the right direction:

Plan is to leave it as is for now and re-adjust at the MoT when we have a gas tester.

13,571 · November 5

You didn't mention the constant need to beat them off with a shitty stick.

6,396 · November 5

18 minutes ago, inconsistant said:

You didn't mention the constant need to beat them off with a shitty stick.

Actually, you jest but you're kind of right!

The P6 used to land you in endless conversations with old men. I say conversations but they were mostly monologues from them on their memories of the car. I know it sounds mean but it was one of the most annoying parts of ownership, especially for a miserable anti-social git like me.

I've hardly driven the Porsche, and both the admiring approaches have come from women in their 20's. I'm 54 and don't look like Brad Pitt, so I'm pretty sure I wasn't the draw. Both commented on how gorgeous it was and one even took a photo! One of them was with her dad, and he wasn't interested 🤣

2,173 · November 5

Amazing ND, well done on the fix and perseverance.

I will also say... my intermittent wiper setting doesn't work, nothing at all. I've tried everything and still nowt. I've also rebuilt the entire fuse box/ board (well worth the time and effort). I just live with off/ slow/ less slow wipers!

My car is also 1981, even though it's registered on a Y plate; it spent the first two years of its life in Ireland. Fun fact - only 1981 cars have the 'Porsche' script embossed on the door cards!!

6,396 · November 5

9 minutes ago, Rusty_Rocket said:

Amazing ND, well done on the fix and perseverance.

I will also say... my intermittent wiper setting doesn't work, nothing at all. I've tried everything and still nowt. I've also rebuilt the entire fuse box/ board (well worth the time and effort). I just live with off/ slow/ less slow wipers!

My car is also 1981, even though it's registered on a Y plate; it spent the first two years of its life in Ireland. Fun fact - only 1981 cars have the 'Porsche' script embossed on the door cards!!

Brilliant - I did wonder what I'd done to get embossed Porsche script. Handy in case you forget, I guess

13,120 · November 5

Really chuffed for you that this is finally going in the right direction pal. Hope you bond with it now you can get some miles on 👍

13,571 · November 5

I was going to say mine doesn’t have Porsche written in big across the door but just checked the photos and it does. Silly but I’ve not really noticed before.

6,396 · November 6

There was another girl who approached me in Lidl car park earlier this week - admired the car, but reckoned she'd never have anything to do with bloke who drove round with wonky front wheels, and she reckoned the tracking was just over 1 degree positive. She looked a bit like this:

so I didn't question how she could be so precise, and just prayed the Trackace would arrive from @juular before I saw her again.

Luckily it turned up yesterday and I had some time between meetings to try it out. Used the videos on the Trackace website to set it up (not that complex) and ended up with this:

OMG!!!!

As you can imagine, I whipped the wheel off and set to turning my rod. Tried a couple of turns first which was too much, so went a turn back in and ended up here:

Bang on 0. That'll do pig.

Really hope I see Marisa again.

10,866 · November 6

Does it feel different?

I mean driving the car after tracking up - not life after meeting Marisa

6,396 · November 7

Just done its first run down to Bristol:

Feels much the same tbh. Perhaps a little sharper in the corners.

70 is an easy, pretty quiet canter on the motorway with plenty in reserve if needed. Sits at about 3200 rpm at that speed, but this engine is (relatively) quiet and refined so the cabin noise is probably less than in the 2002 R50 BINI. The ride is loads better than the BINI mind.

13,101 · November 7

Whether chicks dig mouldy old 924s in 2025 is debatable. However, back in the early 1990s, when I was about 19 and lived in west London, I had a Guards Red 924 and I can confirm that it did not have an adverse effect on my sex life. Admittedly, I had a full head of hair and was much better looking back then.

Good old days.

6,396 · November 7

I'd have put out for you if you were driving that.

11,117 · November 7

4 hours ago, N Dentressangle said:

Perhaps a little sharper in the corners.

Corners are interesting in my 944S, but it's what I understand is called 'pointy'. It loses grip relatively early at the front, then if you press the loud pedal, the back runs wider and the line tightens. It's really odd. None of the wheels feel like they're particularly well stuck to the road, but the car seems to keep going in the direction that it's supposed to. I used to go out late on a wet night and circumnavigate a deserted J24 M1 at 80mph, but then they installed traffic lights all the fucking way round it and the fun was over.

13,571 · November 9

On 07/11/2025 at 10:53, N Dentressangle said:

Just done its first run down to Bristol:

Looks like it’s sitting a bit high?

6,396 · November 10

Just standard ride height front and rear - I haven't changed anything suspension-wise.

6,396 · November 15

So, the Porsche has been busy just being transport. Here's a moody twilight visit to Lidl earlier in the week:

Took it up to see a mate in Bewdley yesterday. 130 miles or so in torrential rain thank to Storm Claudia, so a real test for the car. But, we made it there and back, and uncovered a few more snagging areas into the bargain, which is the purpose of the exercise. Here she is in a very damp Worcestershire, just next to the primary school I went to in the 70's:

As for the snagging, it amounts to the rear demister not working, wet carpets inside the car, and the passenger electric window packing up. Plus a bit of a shriek occasionally from the fan belt, but that may have been the disgusting weather.

The heated rear window took a little diagnosis:

The current for the element is carried up one of the gas struts with the other side providing the earth. That's the brilliant idea, anyway, but in practice it's a load of bollocks. Although the meter showed we were ostensibly getting 12v at the element, there was not enough current to light my test (reversing) light, as shown in the pic. The strut would conduct only if it was wiggled correctly, and the earth dysfunction was similar.

Once I'd re-soldered the tab back onto the element (yeah Porsche, thanks for that. I am shit at soldering) I rigged up direct wiring to the element for current and earth, bypassing the stupid strut nonesense. Works a treat now.

Next job was the wet carpets, with suspect #1 the sunroof drains. Some experiments pouring water into them made me think they'd been falsely accused, and I now think it's the indicator repeater grommets in the inner wings. Depending on how easy it is I might pull the wings off and clean out the mud trap at the base of the rear of the wing where it meets the sill, and slap some sealant on the grommets while I'm in there.

The electric window was the result of something I should have fixed properly in the first place. For complicated reasons the passenger electric window current runs through the driver's side switch. All the switches worked fine and the window would go up OK but not down, so I knew it must be a poor connection somewhere between the driver's side and passenger side switches. The obvious place would be the plug connectors behind the driver's side front kick panel, so I had a look:

See that loose female spade terminal? The one that looks like it should be in square plug? That'll be the problem.

I pushed it back in a few days ago and hoped that would sort it, but opening and closing the door has obviously pulled it out again. Will investigate for a more permanent solution.

12,241 · November 15

Dang ..Going by the title i thought Claudia was the chick from Lidls ..and you'd shagged her !

6,396 · November 15

15 minutes ago, Christine said:

Dang ..Going by the title i thought Claudia was the chick from Lidls ..and you'd shagged her !

In my dreams 🤣

12,241 · November 15

Enzo said

Porsche 924 Scheiße - bizarre electrical problem, mystery solved...

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