Wiper Delay Unit

[PaulB]

Has anyone found an alternative to the original Lucas Wiper Delay Unit? In this modern age I thought there may be an electronic version available which does the job, instead of the original thermal type unit?

[Niss]

I can remember making one for my first car an Austin 1300GT from a design in Practical Electronics, the magaizine is long gone as is the car. Maplins do a kit.
http://www.maplin.co.uk/p/velleman-w...lder-kit-ve03d
One of the reviews gives a lot of information about the kit.

[jpyke]

Has anyone found an alternative to the original Lucas Wiper Delay Unit? In this modern age I thought there may be an electronic version available which does the job, instead of the original thermal type unit?

Yes is my answer, but it's not a simple fix so may not be of great help to you:

I've used a VW '99' relay which gives me programmable intermittent (there are variants which are fixed intermittent but I've used part number 357 955 531 which is programmable). It will require a change to the wiring which isn't overly complex, but it's certainly not a straight swap. I have a MK1 car which has no intermittent, but have used a MK2 switch and have a small inline addition with the relay which plugs straight into the original main harness.

The 99 relay gives a programmable intermittent between ~3 and 30 seconds by turning the wipers to intermittent, back off, waiting the required time and turning back to intermittent to set the delay. It also gives approximately 3 wipes automatically when you use the windscreen washer. The downside though is that you have to route the washer signal through it too, which will require a small relay to invert the output signal as the 99 relay supplies positive voltage to the washer output whereas the car expects a switched ground. You also have to disassemble the wiper switch and move a few contacts over as originally the switch provided the feed to park the wipers whereas the 99 relay needs to do this itself.

However, if you were starting with a MK2 car which already has intermittent wiring you may be able to do a much simpler conversion. Schematics for the 99 relay are readily available online.

James

[PaulB]

I have just spent half yesterday afternoon trying to understand how the wiring of the wiper motor works and failed, so that I could work out whether a modern wiper delay unit would work and how to wire it. Does anyone know how it works and whether its documented anywhere.
Thanks.

[jpyke]

Does this help? http://socforum.com/forum/showthread...d-how-it-works

[Carboy0]

Yes is my answer, but it's not a simple fix so may not be of great help to you:

I've used a VW '99' relay which gives me programmable intermittent (there are variants which are fixed intermittent but I've used part number 357 955 531 which is programmable). It will require a change to the wiring which isn't overly complex, but it's certainly not a straight swap. I have a MK1 car which has no intermittent, but have used a MK2 switch and have a small inline addition with the relay which plugs straight into the original main harness.

The 99 relay gives a programmable intermittent between ~3 and 30 seconds by turning the wipers to intermittent, back off, waiting the required time and turning back to intermittent to set the delay. It also gives approximately 3 wipes automatically when you use the windscreen washer. The downside though is that you have to route the washer signal through it too, which will require a small relay to invert the output signal as the 99 relay supplies positive voltage to the washer output whereas the car expects a switched ground. You also have to disassemble the wiper switch and move a few contacts over as originally the switch provided the feed to park the wipers whereas the 99 relay needs to do this itself.

However, if you were starting with a MK2 car which already has intermittent wiring you may be able to do a much simpler conversion. Schematics for the 99 relay are readily available online.

James

Hi James,

I am really interested in your comments above, I have a MK2 switch and have bought a VW .99 relay and I have worked out the plugging necessary. For the life of me I can’t fathom out how to trigger the”I” terminal using the switch’s intermittent switch. Can you advise on how you modded the switch please?

[dasadrew]

I have just spent half yesterday afternoon trying to understand how the wiring of the wiper motor works and failed, so that I could work out whether a modern wiper delay unit would work and how to wire it. Does anyone know how it works and whether its documented anywhere.
Thanks.

Wiring and how it works is all in the Technical Section under the Electrics chapter

https://socforum.com/forum/forum/stag-owners-club/technical-section/electrics/755452-windscreen-wipers-electric-circuit

https://socforum.com/forum/forum/stag-owners-club/technical-section/electrics/755454-windscreen-wipers-self-park-function-explained

Drew

[Carboy0]

Thanks Drew, These help a lot. I also have the RHD Mk2 colour wiring diagrams, so I can work out the circuit. James (jpyke) said that he had adapted his Mk2 switch to run a modern electronic relay. I was hoping to understand his switch mods.

[jpyke]

Thanks Drew, These help a lot. I also have the RHD Mk2 colour wiring diagrams, so I can work out the circuit. James (jpyke) said that he had adapted his Mk2 switch to run a modern electronic relay. I was hoping to understand his switch mods.

Apologies for the delayed response - haven't been on here in a while. Hopefully the below will help - this is what I needed for a MK1 system. The Wiper switch is bottom right and will need to be configured to connect as shown. I can't remember whether I had to cut any wires or whether it was a case of carefully popping the terminals out and moving a few about. Stupid of me not to have made notes at the time.

The No. 99 relay is on the left; it expects to control the parking of the motor and needs to see the park switch change state - it is because of this that the switch needs reconfiguring. Also, as mentioned above you'll need another small relay to invert the washer signal.

IMG_0401.JPG

[Carboy0]

Thanks James that’s great. I can’t read your notes in the bottom right hand corner of the drawing, in the drawing of the switch unit between the slow and intermittent switches.

You also refer to “another small relay to invert the washer signal” but it’s not shown.

[Goldstar]

Peter Howells brought a modern relay to the SOCTFL meeting on Friday night. Mike Allen took it away to fit and trial. I’m sure Mike will report back as soon as he has fitted it.

[jpyke]

Thanks James that’s great. I can’t read your notes in the bottom right hand corner of the drawing, in the drawing of the switch unit between the slow and intermittent switches.

You also refer to “another small relay to invert the washer signal” but it’s not shown.

Yes the resolution could be better - I'll do a proper scan tonight and upload the new result - I'll also add the extra relay. (Sorry, I originally made the drawing for my records rather than to share around so I'll tweak it a bit to make it more helpful). To invert the wash signal for use with the motor in the car you need to tee into the dotted line in the diagram and feed this to the coil of another relay, then use the switched contacts to switch the signal coming from the motor in the car to ground. (I'll show this in the drawing update). As I say above, the 99 relay expects to see a positive input to on the wash input; it then uses this to perform 3 sweeps of the wiper automatically, which is nice to have. This is why the 99 relay needs to have the park signal going through it - so it can count the sweeps.

[jpyke]

Here's the updated version. Looks like the compression is happening on this site, so I can't get a better resolution for you I'm afraid. The notes you can't read say "in off only" and was a note to indicate that the intermittent can only be used with the stalk in the off position (as enforced by the metal gate on the switch). I've also added the MK1 wiring colours to some of the wires.

The second image shows the mod, which I did as a self-contained plug-in conversion. This meant I didn't have to modify the main loom at all. The big relay is the 99, the small miniature one by the side inverts the wash signal as described above. As yours is a MK2, you might be able to do the conversion in a simpler way, given that you already have an intermittent relay, but I suspect you might find you need to do something like mine, given the change needed to how the switch is wired.

[Carboy0]

I understand now about the washer motor. Triumph made the Mk2 a little easier, the washer switch takes the +12v signal from the switch and feeds the pump and earths from the pump, which means that the Mk2 doesn’t need the extra relay.

Also, I doubt very much that the .99 relay is counting sweeps, it’s more likely to be a 5 second delay off timer in the relay, which is about three sweeps.

The challenge with the Mk2 Intermittent switch and 2DA thermal relay is that, switching the stalk collapses the intermittent circuit rather than triggers it, so it looks like I will need to play with the contacts in the switch.

Hopefully Mike Allen has/will come to the same conclusion as me.

I will report back.