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Intermittent Wipers v2

In 1975 when my spitfire was born, British Leyland thought the height of modernity was having wipers that had two speeds, slow and a bit slower. However the windscreen is not that big so the speed of the wipers is adequate. What does annoy is the lack of intermittent or even a flick wipe.

So the challenge was to get intermittent wipers on a 1975 Spitfire 1500. The 1975 1500 still had the same steering column as the earlier MKIV and probably the earlier marks as well. That means it did not have the later TR7 column with the wiper controls on the steering column stalks but on a combined washer pump (manual) and two speed wiper switch on the dashboard.

Now I only had a few criteria for my planned install of intermittent wipers:

  • It had to be cheap, not that I am tight but I then get to spend more money on other upgrades, that’s my excuse anyway
  • Nothing to be visible and no drilling of the lovely wooden dash
  • Dashboard to retain its original look including the wiper switch
  • Easily remove the intermittent wiper and return to original if required
  • No changing of wiring loom (cutting splicing soldering) that can’t be undone
  • Still have two speed wipers when non intermittent working
  • Did I say it had to be cheap?


Sourcing the parts

So where to start? Well obviously I needed some sort of timer/relay device to make the wipers wipe only every now and then. Now I know that there are timer relays available but they are over £18! and the kits that you can buy are going to be at least a tenner, well over my budget. So an alternative had to be sourced.

Ford Fiesta Relay
Fig 1 - Ford Fiesta Relay

Scouring Ebay I came across a possible solution, a Wiper timer/relay for a Ford Fiesta. Now there are some people on Ebay trying to sell these relays for £118 yes £118 obviously well above my budget. There were second hand units for around a tenner again above my budget but I managed to find a brand new one for £1.65 including p&p now that was in my budget. To search for one of these units your self the engineering part number is 92GG-17C499-AB and the manufacturers part number is 1012240. The one that I bought seemed to be a genuine Ford part and not a knock off Chinese copy. So I now have the relay but the next step was to work out how to wire it up.

The Theory

The relay had the pins helpfully marked 1 2 3 5 6 7 but no indication as to what the pins were for. Searching the internet for a circuit diagram of the relay was fruitless. In the end I took the cover off the relay to try and work out what each pin was for. Finding the pins for the relay contacts was straight forward but finding the purpose of the others was more difficult. I did not want to connect the relay incorrectly and waste my £1.65. In the end I used a strong magnifying glass to read the laser etched writing on the control chip. The chip is a U642B specifically designed for intermittent wipers. Searching the internet for a data-sheet for the chip was more successful. With the example circuit and my trusty multimeter I worked out what all the pins were for.

Relay Connections
Table 1 - Relay Connections

So to make it work I only needed to connect Ground to pin 2, +12V supply to pin 6, a connection to the wiper motor park switch to pin 1, a connection to the wiper motor on pin 3 and a +12v signal from a switch that turns the intermittent function on to pin 5. Simples!
Now it might seem daunting but when you start looking at the original wiring diagram all the connections to the wiper motor that you need appear on the wiper switch. So you don’t need to go anywhere near the actual motor.

Fig 2 shows the original wiper wiring for my Spitfire 1500, if you have a later 1500 the wiring will be different due to the wiper controls being on the stalk and there is an electric washer pump. The wiper motor self parks using the +12V supply on pin 5 of the motor. As the motor is not parked the park switch in the motor is closed and the +12V is extended from the motor on pin 3 to the switch on pin 4. As the switch is in the off position the +12V from the motor on pin 4 of the switch is connected to pin 3 of the switch, wipers slow. Pin 3 of the switch is then connected to pin 4 of the motor. This drives the motor until it reaches its parked position. When the parked position is reached the park switch opens and the +12V is removed from pin 3 of the motor and the motor stops.

Original Wiring
Fig 2 - Original Wiper Wiring

Fig 3 shows the new wiring with the intermittent relay in circuit. The intermittent relay intercepts the parking lead from pin 3 of the motor, this is connected to pin 1 of the relay. Pin 3 of the relay is connected to pin 4 of the wiper switch and this completes the parking circuit. The +12V supply on pin 2 of the wiper switch is removed and extended to connect to pin 6 of the relay, pin 2 of the wiper switch and one side of the intermittent switch S2. The other side of the intermittent switch S2 is connected to pin 5 of the relay.

Revised Wiring
Fig 3 - New Wiper Wiring

When the intermittent switch S2 is operated, the intermittent relay operates, puts +12V out on pin 3 which fools the motor into thinking that it is not parked and so operates and wipes the screen. When the motor parks after one wipe of the screen the timer function of the relay starts counting and repeats the operation of the wipers after around 6 secs have elapsed. This continues until the switch S2 is turned off.
So that's the theory how do we do it in practice?

What you will need?

  • Intermittent relay
  • Suitable gauge wire something will handle around 15A will be ample
  • Male and female Lucar connectors and insulators and a suitable ring terminal. I prefer to solder rather than just crimping but that is personal preference
  • Suitable switch a simple on off is all you need

Method

Working with electricity can be fraught with danger. Some Triumphs have very few fuses which means you risk shorting the battery out potentially putting 500A through a bit of wire designed to take 15A. The wire will melt, melt other wires and potentially set your car, garage and then your house on fire. The insurance won’t pay out on a technicality, your wife will divorce you. You will be homeless, penniless, wifeless, living on the streets and most importantly without your Triumph. Please be careful.

  1. It’s a lot easier to do the wiring with the wiper switch removed. The knob on the switch has a small hole underneath. With a suitable small implement press up in the small hole and pull the knob off the spindle
  2. Unscrew the silver bezel of the wiper switch and remove the switch from the rear of the dashboard.
  3. Identify the wires on the rear of the switch. Pin 1 should be Blue/Light Green and is wiper fast, pin 2 should be Green and is ignition controlled +12V, pin 3 should be Red/Light Green and is wiper slow and pin 4 should be Brown/Light Green and is the park lead from the motor.
  4. You will need a suitable switch to turn on the intermittent relay. I used a nice old fashioned switch that I mounted behind the dashboard on the metal supporting frame of the dashboard. It can’t be seen but is easily accessible for operation
  5. Remove the Green wires from pin 2 of the switch. It will have 2 wires as one is the feed to the wiper motor.
  6. Make up a small wiring loom that connects to the Green wires you have just removed, pin 6 of the relay, back to pin 2 of the wiper switch and then to input side of the intermittent switch S2. Make the wires a suitable length to reach the different components.
  7. Connect the output side of switch S2 to pin 5 of the intermittent relay
  8. Find a suitable ground connection and make up another lead to connect to pin 2 of the intermittent relay. A suitable screw or the clamp of the speedo should be a good ground.
  9. Double check all your wiring.
  10. Repeat step 9.
  11. Make sure there are no exposed wires and/or connectors that could short out and start a fire.
  12. Turn on the ignition and check the operation of the wipers, do they still work on both speeds? Do they still park? If the answer to either question is no go to step 9.
  13. If all is well in step 12 turn on the intermittent switch S2 with the wiper switch in the off position. You should find that the wipers now wipe every 5 to 6 secs. If they don’t wipe intermittently go to step 9
  14. If all works as expected refit the wiper switch, fit the intermittent switch in a suitable location and locate the relay in a suitable location. I cable tied the relay to the wiring loom.
  15. Retry the wipers and intermittent operation after refitting all of the components
  16. If the main wiper switch and the intermittent switch are both turned on together it does not seem to have to much of an adverse effect except that the intermittent relay clicks every wipe. Best not to have them both on at the same time though just in case
  17. If all is well sit back, enjoy a suitable beverage and bask in the glory that will be heaped upon you. If all is not well go to step 9

Is That It?

Well yes, if all you wanted was intermittent wipers you now have them. However there are a few things that you can do to improve things further.

Wash Wipe

You may have noticed the intermittent relay has a pin that we have not used, pin 7. Modern cars have a facility where when you operate the windscreen washers the wipers come on automatically for 4 to 5 wipes. Pin 7 is the signal wire from the electric washer pump to operate the wipers.

Problem 1 – My Spitfire does not have an electric washer pump.

Problem 2 – I want to keep the original wiper switch/pump and be able to revert to manual washers if necessary.

Problem 1 is easily overcome by purchasing an after-market electric washer pump. Make sure you pick one that has a tube connection for input and output and not one designed to sit at the bottom of a washer fluid reservoir.

Problem 2 was somewhat trickier. Several people on line had modified their wiper switch/pump to have a switch to operate an electric washer pump but this has the problem that it can’t be returned to original, and if a new switch is required the new one would also need to be modified. A different solution was required.

What was required was a method of switching +12V using the pressure that the manual washer pump could generate. Searching the internet I found that pressure switches are expensive well over £10, something cheaper was required.

A bit of lateral thinking led me to think where I had seen a pressure switch in use. My eureka moment came when I thought of washing machines. Apart from having to share a garage with one I don’t have much interaction with them until they don’t work. The call goes out from she who must be obeyed that the world is about to end as the machine isn’t working. Washing machines have lots of useful and interesting parts inside them. One interesting part is the water level sensor that never gets wet. A tube from the drum is connected to the sensor, as the level of water rises the air pressure in the tube increases. When the water level gets to a predetermined level the sensor operates and the flow of water is stopped.

Rummaging through my box of useful bits I was dismayed to find that I did not have any of these sensors. Back to Ebay to see what I could find. New ones were out of the question as they were £20 plus. I found a suitable pre-owned candidate, it had four standard Lucar connectors that were supposed to be in a plug but I could work around that. The four connectors indicated that the internal switch could be a changeover type so it should work as I wanted. Most importantly it was £4.57 inc p&p. The order was placed.

When the sensor arrived I tested it to see if it would indeed operate on the pressure that the manual pump could generate. By disconnecting the original pipes on the pump and connecting a length of washer pipe between the manual pump and the sensor I was ready to test. On first try it did not work but I soon worked out why. The inlet on the pump from the washer bottle was letting all the pressure escape. There is a one way valve in the washer bottle that stops the water flowing back in to the bottle when the pump is being used as designed. By blocking the inlet pipe with my finger the sensor could be heard to operate when the washer pump was operated. The actual switch was tested and proved to be a changeover switch. Ideal. One thing to be aware of is the switch I obtained seems to have a two stage switch, one contact operates at a lower pressure than the other. I chose to use the lower pressure contact to save the manual pump having to work too hard.

Washer Pump Wiring
Fig 4 - Washer Pump Wiring  
How not to wire wipers
Fig 5 - How Not To Wire Wipers

Motor M2 is the washer pump motor and the switch S3 is the repurposed washing machine water level sensor.

According to the data sheet for the U642B chip that drives this relay, the washer pump signal going in to the relay on pin 7 should be a +12V input going into the relay. I found that connecting it this way, the wipers were running all the time.

The reason the wipers were running all the time was the relay was connected to one side of the pump motor and the other side was connected to ground. There was +12V coming out of pin 7 of the relay and the ground on the other side of the motor was enough to make the relay think that the washer switch was on all the time but there was not enough current to operate the motor.

So the wiring was changed to make one side of the motor +12V and the other side switched ground via the sensor switch S3. This switched ground is also then extended to pin 7 of the relay as per the diagram in Fig 4.

With the change made the wipers and washers were tested again and all worked as they should. A short press on the manual washer pump operated the pressure switch S3 which operated the pump. The relay operated and the wipers made three sweeps of the screen.

Variable Delay

There is a possible way of changing the delay of the intermittent wipe. According to the data sheet if you put a 10KΏ potentiometer between the intermittent switch and pin 5 of the relay you should be able adjust the delay between wipes. I have not tried this but maybe I will try it in the future.

Flick Wipe

You may want the ability to just flick the wipers once. You can do this by putting a non locking switch in parallel with the intermittent switch S2. A quick flick of the non locking switch will activate the intermittent wipe function of the relay but it will only wipe once. The problem will be the switch and where to mount it.

Tips and Tricks

  1. The numbers on the relay are easy enough to read when not in the car and you can angle the relay to catch the light but in the dark depths of behind the dashboard of a Spitfire they are virtually impossible to read. I wrote the numbers around the side of the relay with a Sharpie.
    .Relay Pins
  2. The relay is designed to be fitted into the fuse box of a Fiesta, and the spade connectors are longer than the corresponding individual Lucar connector. This means that there would be a portion of the spade connector on the relay exposed. This could cause a short circuit if say the +12V supply touched a ground. I cut small lengths of heat shrink to cover the base of the spade terminals.
    Relay
  3. You need to block off the input from the washer bottle to the manual washer pump if fitting the water level sensor switch. A suitable method is to use a short length of washer pipe and block it off with a suitable screw. I covered up the brass screw used with some heat shrink after the photo was taken.
    Washer Pump
  4. The water level sensor that I used had four connectors that I was only going to use the two middle ones. I again used some heat shrink to cover the two unused connectors.
    Pressure Switch
  5. I fitted the electric pump inside the car rather than under the bonnet. There is of course a risk that there could be a leak. The manual pump was inside the car as well so the risk should be the same. The pump that I bought only had one rib on the pipe connections, to try and ensure a water tight seal I put some small cable ties around the pipes.
  6. Try and find where you are going to fit all the different bits and bobs before sorting out the wiring. Once you know the distance between the components you can cut the wiring to the correct length and make a nice neat job, unlike mine.


What Did It Cost?

It is hard to quantify all the costs involved as things such as wire, connectors, switch, heat shrink and pipe I already had and did not have to buy specially.

If you just want the intermittent function and you have all the consumables such as a switch some wire and connectors, then you will just need the relay. If you want the wash wipe then you will need a pump if your car does not have one and the pressure sensor if you don’t already have a washer switch. This is what I paid for the bits.

Relay, Ford part No. 1012240 - £1.65
Electric Pump Autobar 825  - £5.39
Hotpoint pressure switch - £4.70
Total - £11.74

 

Written by: Malcolm Huxtable