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Intermittent wipers controller build.

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Old 12-05-2004, 06:57 AM
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Fleetwood
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Default Intermittent wipers controller build.

INTERMITTENT WIPER CONTROLLER

This is my solution to the wiper controller on my 1979 vette, which was beyond repair when I bought my car. This is what I did to get my wiper system working again, as close to the original system as possible, without looking like some add on unit.
Before replacing your old unit make sure that it’s not just a simple fix to get it working again, may just be a faulty relay, or a simple fault on the printed circuit board (common with older printed circuit boards). If I had been able to repair mine I would have, but I had no alternative than to build up a generic unit.
Because somewhere along the tough life of my car, the wiper motor had been changed, the motor I now have, does not have the internal relay that operates the wiper motor, when the windshield washer is pushed on in the switch ”off ” position, I was not able to incorporate this feature in my design. Not a big deal as the washer works in both the low & high, as well as the mist position.

You will need basic skills in soldering, as well as reading, & understanding circuit drawings. The Velleman MK111 adjustable interval timer kit I used is very simple to constructed, but having said that, overheating a component with to much heat from the soldering iron, can cause irreparable damage. Make sure you fully understand what is required, before attempting this.


Red = standard switch green = intermittent switch.


WHAT WIRING NEEDS TO BE REMOVED.

The circuit diagram posted here is not very clear, unfortunately to get a bigger & clearer image requires a bigger size jpg. If you do not have a copy of Haynes repair manual, (pages 12-50 & 12-51), I can probably send you a larger copy via email.
Looking at the circuit diagram, it can be seen that the intermittent wipers were marked in dotted lines. The reason being that this was an optional extra in 1979(I am not sure about other years).
The intermittent pulse wiper controller,& it’s associated wiring need to be removed, all except the 3 way terminal block, that attaches separately to the switch, & it’s wiring, marked 904(white),141(brown/white) & 903(dark green) on the diagram. These wires will be used again on the new controller. Reinstate the wiring to the standard switch as shown on page 12-50.
Once this is completed, the system needs to be tested electrically. You should have the following operations, mist, off, low (which will become intermittent), low, & high.
A word of caution here, this is what I would say is the hard part. Take your time, follow the wires using the colour codes, marked on the diagram, & take it one wire at a time.




HOW THE CIRCUIT WORKS.

Circuit consists of a timer & 3 relays R1, R2 & R3, that operate in a time delay sequence, depending on the state of the timer circuit.
As long as the dark green wire (903), is grounded at the wiper switch, which it is when the wiper switch is in the mist, off, low & high positions, the intermittent timer circuit will be de-energised by R2.When the coil of R2 is energised, the NC(normally closed) contact of R2 will change to an open contact, preventing the 12V+ supply from energising the timer circuit.
When the wiper switch is placed in the intermittent position, the dark green wire (903) is no longer grounded. When this happens R2 is de-energised, returning the contact of R2 back to the NC position. This in turn now feeds 12V+ to the timer circuit.
R1 now closes, changing its NO (normally open) to a NC contact, which inturn feeds 12V+ to the coil of R3, opening the NC contact of R3, which causes an open circuit to the purple wire (92).
Depending on the setting of P2, which is the potentiometer built in to the wiper switch, R3 will remain energised, keeping the NC contact of R3 open & the wiper motor off.
After the timer circuit has timed out R1 coil is de-energised, causing the contact of R1 to return to the NC position.
The pause P1 prevents R1 from operating for a preset time (2 sec) to allow sufficient time for power to flow to the wiper motor, to operate the motor for one operation.
After P1 has timed out the timer operation is repeated, & R1 becomes energised again.

BUILDING THE CONTROLLER.

http://store.qkits.com/moreinfo.cfm/MK111

I used an adjustable interval timer, basically because I needed power to the motor to stay on for 2 seconds, so I needed the additional pause function. For some reason I needed to keep power at the motor to complete one function. It may be different in you case.
The timer unit, which comes with full instructions on how to build, is a simple unit to construct, & should be available at most electronic supply stores. I used a MK111 made by Velleman.
You will also need two additional relays, one small one, which is basically needed to control supply to the timer via the dark green ground wire (903). I found a PC board mount type, & glued a plastic piece to the side, then screwed it on to the metal board supplied with the box I bought.
R3 is a standard auto relay used to drive lights, It is a bit big for the application (30A), but can still fit in the box.
The box I used is also available from electronic shops, & measures 125mm x 65mm x 40mm deep.
The one I used came with a plastic lid & a metal lid, I used the metal lid to mount onto.
The fuse hold can be seen in the picture mounted onto the side of the box, also available from electronic stores.

FITTING THE CONTROLLER IN CAR


Self-explanatory if you follow the diagram. Points to remember are the trim pot, that fits into the pulse location on the timer, is left out & the wires 904 & 141 are soldered in its place.
Also the purple wire needs to be cut, & two additional wires connected where the cut was made.
These two wires are now fitted across the NC contact of R3.
The 12V+ fused supply, needs to be a switched supply. Meaning that the 12V+ is only energised when the Ignition is switched on.
I think that about covers everything, if you have questions feel free to ask.

Neil.

Last edited by Fleetwood; 12-05-2004 at 07:09 AM.
Old 12-05-2004, 08:47 AM
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BigBlockk
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That is an excellent writeup. Wish I could do that small stuff. Good job!

BigBlockk

Later.....
Old 12-07-2004, 12:25 AM
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Fleetwood
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Thanks BigBlockk,One thing I forgot to mention is the speedo & tach pod needs to be removed to access the wiper switch.

Neil.
Old 12-07-2004, 09:50 AM
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Wow nice work. Most electrical stuff is built for economy so when you do it yourself you can do cool overkill type stuff, which you did, stuff like using oversized wires, overrated components, making your circuitry accessable for servicing, etc.

One note is that on schematics the letter K is generally used to name relays, not R. Resistors get to be R.

Thats quite the impressive list of circuit kits that website offers, they're just down the road from me too! Just curious, what is the chip that they used in the MK111?

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