Windscreen wiper electrics

[The Hatter]

Anyone know what this is and how it works?




When it's plugged in, the SEAC wipers run all the time even with the ignition off. When it's disconnected, the wipers only run on full speed and don't self park.

It seems pretty well sealed up so I can't check it's contents. I'm suspecting the actual wiper motor is faulty and maybe not this unit but any advice would be welcome.

[gralin69]

Pektron still exist may be worth giving then a call
http://www.pektron.co.uk/
showing some wiper control modules but not as yours

[JMF894]

Hi Martin,

Isn't the wiper motor's action simply determined by the electrical signal/pulse that it receives? The speed/park etc being influenced by the setting that the circuit is set to by the column stalk? I would have though more likely the fault lies between the wiper column stalk and the motor itself, possibly a relay or capacitor?

I am no expert of course, but i hope my though process above makes sense even if it's incorrect.

Cheers Jimbo

[Wedg1e]

I tried to reply to this earlier in the week but PH was on the blink and I've only just remembered... this is the best info I can find at the moment:

[The Hatter]

Ian,

What's the block with the square wave in it? Does it act like a relay that switches on then off every few seconds?

I've swapped the wiper motor for a known unit and got the same behaviour (on all the time (although I need to check the ignition circuits too)) and all the other column switches are fine so I think the wiper column switch is OK - so I'm still suspecting this unit. More checking tomorrow...

[voltage_maxx]

Intermittent wipe unit. If you look at the relay layout diagram on the glove box rear, you'll see it referenced.

I'm fairly sure there's a relay in there, as it makes a clicking sound when the interittent wipe function is activated.

[Wedg1e]

The Hatter said:

Ian,

What's the block with the square wave in it? Does it act like a relay that switches on then off every few seconds?

I've swapped the wiper motor for a known unit and got the same behaviour (on all the time (although I need to check the ignition circuits too)) and all the other column switches are fine so I think the wiper column switch is OK - so I'm still suspecting this unit. More checking tomorrow...

Yep, it's a fixed-period timer circuit driving the relay. Not much in there: 8 resistors, 6 diodes, three capacitors, two transistors... and a relay
My guess would be either a transistor has gone short, holding the relay on, or something equally simple.
If you get stuck, post it up to me and I'll sort it. Would be nice to see if it could be modified for variable period too.

[mikeb]

Ian, you are the king of Wedges mate! I still reckon that you should shove your job, open up a garage and we can all bring our cars for you to fix.

MikeyB

[The Hatter]

Great offer Ian, thanks! I haven't eliminated the column switch yet so I'll do that first. The washer button on the end of the switch is not functioning so I'm trying to figure out what the switch action actually is. On the switch connector block I've got:

off: green/red connected to green/brown
Intermittent: Green/white connected to green/brown
Slow: green/red connected to dark-green/brown(two wires on this one!)
Fast: green/blue connected to dark-green/brown(see slow speed)
...plus on the car connector block the green/white wire is jumped to the green/red wire

There's two other wires on the switch that never connect to anything - green/black (washer, I believe) and green/yellow.

Oh and with the Pektron unit connected the wipers run all the time on slow speed with the ignition on, not with the ignition off.

Anyone know what the green/yellow wire does, and when it's connection should be 'made' on the switch?

[mrzigazaga]

mikeb said:

Ian, you are the king of Wedges mate! I still reckon that you should shove your job, open up a garage and we can all bring our cars for you to fix.

MikeyB

+1..

[Wedg1e]

The Hatter said:

There's two other wires on the switch that never connect to anything - green/black (washer, I believe) and green/yellow.

Oh and with the Pektron unit connected the wipers run all the time on slow speed with the ignition on, not with the ignition off.

Anyone know what the green/yellow wire does, and when it's connection should be 'made' on the switch?

The Green/Yellow is the input to the Pektron unit when the switch is in the 'Intermittent' position. It should show short to Brown/Dk. Green in that position. You should also have Brown/Lt. Grn shorted to White/Green in Intermittent (I think you said this was so).

Green/Black (washers) should short to Brown/Dk. Green when the wash button is pressed.

Entertainingly, whilst trying to sort this I pulled a spare column switchgear from my stock and found that hardly any of the wiper switch contacts do anything! I had to resort to unplugging the switch on my 390 to get all the facts.
Doesn't help that TVR switched the colours on the loom side of the connectors, just to be awkward

[Wedg1e]

Knocked this up to make things a bit clearer...



FFS, must pay more attention to my own scrawl. Edited to fix wire in wrong place!

Edited by Wedg1e on Tuesday 11th October 22:21

[The Hatter]

That's phenomenal, thanks Ian! I definitely have a problem with the switch so I'll sort that and then see how the Pektron unit responds.

I see Rimmers have an offer on the SD1 column stalks, looks like a good deal. However I haven't been able to get the steering wheel off yet so I can't change the column stalk unit...

[Wedg1e]

No worries, I like a bit of brain exercise once in a while, preferably not for my boss to enhance his lifestyle from.

At the risk of sounding like honestjohn, for a fuller picture of the wash-wipe workings, have a shufty at this really bloody fantastic website

The switch that I dug out of my workshop turned out to be inoperative: I ended up drilling out the 'rivets' and cleaning all the bits to fix it, but you could probably do the same through the hole in the end of the switch. Just needed all the coppery bits polishing up.

Edited by Wedg1e on Wednesday 12th October 19:08

[The Hatter]

As you say... fantastic website!!

I've now got the switch behaving as it should, even on the washer button - the washer button came apart without much of a fight and the rest is visible through the slot in the metal casing.



I've still got the same fault though; the wipers run all the time. Studying the diagrams shows the most likely culprit is the park switch in the motor itself; I'd checked this by substituting a motor that was working fine when removed from another wedge six months ago, now I'm suspecting that both my motors have the same park switch fault!

[Wedg1e]

The Hatter said:

As you say... fantastic website!!

I've now got the switch behaving as it should, even on the washer button - the washer button came apart without much of a fight and the rest is visible through the slot in the metal casing.



I've still got the same fault though; the wipers run all the time. Studying the diagrams shows the most likely culprit is the park switch in the motor itself; I'd checked this by substituting a motor that was working fine when removed from another wedge six months ago, now I'm suspecting that both my motors have the same park switch fault!

The park switch is about the only thing that would account for those symptoms other than the relay in the Pektron being permanently on. Did you find a substitute Pektron?
I'm finding it hard to imagine how the park switch is stuck in the 'run' position though: maybe the wiper was in mid-sweep last time the ignition was turned off before the car was laid-up or maybe the first time you turned the wipers on, the switch changed-over but didn't change back!

You could test the Pektron by poking 12v in on the green and black wires: if it clicks straight away and then clicks when you remove power, I'd say it's kefurkled as the relay shouldn't switch on with no trigger input.

Edited by Wedg1e on Friday 14th October 10:14

[voltage_maxx]

Was browsing the Rimmer bros website for SD1 electrics and happened across this:



http://www.rimmerbros.co.uk/Item--i-DRC2537


Seems there are A LOT of SD1 electrics in our cars

[The Hatter]

That's interesting, so I can get a replacement for a tenner... tempting!

[The Hatter]

I got a new Pektron unit from Rimmers, now I have wipers that park but still no intermittent setting. The 'new' unit looks very old so I assume it's old stock so that may be faulty as well... the switch checks out OK.

At least the wipers now function so I can leave the remaining fault for another day.

[Wedg1e]

The Hatter said:

I got a new Pektron unit from Rimmers, now I have wipers that park but still no intermittent setting. The 'new' unit looks very old so I assume it's old stock so that may be faulty as well... the switch checks out OK.

At least the wipers now function so I can leave the remaining fault for another day.

Could be the electrolytic capacitors in the Pektron having dried out and no longer functioning as timing components...