Controller & Switches FAQs

Question No. 1
How does the Digital Controller work?
When the ignition is first turned on, the Digital Controller will 'system check' the EWP and it will run the pump for approx 10 seconds. The Digital Controller supplies a six volt PWM- pulse width modulation, (10 seconds on – 30 seconds off) to the Electric Water Pump from a cold start until the engine temperature reaches 20◦C below the target (set) temperature. At this point the Digital Controller then supplies a PWM (10 second on – 10 seconds off) till 5C less, then the Controller will ramp up to full system voltage as and when required searching for and locking onto the target temperature.

Electric Thermatic Fan/s will deploy at +3◦C above target temp.
If the engine cools below the target temperature, the Controller will step back from full system voltage down to 6v if necessary and generally it will go back to pwm when highway cruising.

The Digital Controller will indicate when;

The EWP® is running
The target (set) temperature is reached
The supply voltage is too high or too low
The EWP® is running at full supply voltage and is not holding the target temp (Thermatic Fan/s need to be turned on)
There is no power to the EWP®
If you wish, you can look at what the Controller is supplying the pump by connecting a voltmeter to the EWP® motor leads. But remember when the Controller is in PWM mode, the meter will flicker.

Major advances in the new Digital Controller:

Temperature settings are now electronic in that the SET temperatures are now easily set digitally at the touch of a button.
An automatic time-out has been built into the Controller to run the EWP to the target temp or for a maximum of 2mins after ignition OFF, to eliminate the effects of heat soak on engine shutdown. Generally the EWP® will run for less than 2mins because heat soak washes out in about 20 seconds.
A suite of self diagnosis functions has been built into the Controller which will identify cooling problems enabling easier trouble-shooting.
The Controller has a number of monitoring features to keep the user appraised of system operation conditions at all times e.g. Controller on, pump operation mode, cooling system temperature etc.
A new option for mounting the temperature sensor into the top radiator hose is offered in lieu of placing the sensor wiring between the hose and housing or into the thermostat housing. Part no is 0409.
The current carrying capacity of the Controller has been increased from 7.5 amps to 12 amps in conjunction with a significant weight reduction.
A 'Test' function has been adopted which gives the user a visual warning -- on the Controller and remotely -- if a system problem is evident.

Question No. 2
How does the thermal switch ostat controller work?
The adjustable thermal switch ostat is a temperature control device which senses the temperature of the coolant as it leaves the engine,radiator and turns on the electric fan(s) when cooling is needed. The thermal switch ostat is adjustable through a wide range of temperatures by turning an adjustable screw located on the controller.

Question No. 3
I would like to place the Thermal Switch (Part No. 0401, 0402, 0404) unit in the vehicle’s cabin rather than under the bonnet. Is this possible?
No, Davies, Craig Thermal Switch (Part No. 0401,0402 & 0404) must be mounted in the engine compartment near the radiator.
The EWP/FAN Digital Controller (Part No. 8020) should be mounted inside the vehicle cabin to access the controls and feedback information away from direct sunlight and should not be exposed to excessive heat.

Question No. 4
Can I place the probe from the Electronic Thermal Switch (Part 0402) into the water system?
The probe from the 0402 is designed only to go into the radiator fins and measure air temperature. Although you may be able to install it into your water system, the part of the probe where the wires enter the bulb is not water proof. We can't guarantee correct operation and any warranty will be void if the probe is inserted into water. This probe measures electronic resistance which is different to how a Mechanical Thermal Switch (Part 0401) water type sensor measures temperature to activate a switch. Should you want a probe that can be installed into your water / coolant system, please use the Mechanical Thermal Switch (part number 0401).

Question No. 5
Can I use the EWP & Fan Digital Controller to run my Thermatic Fan Only?
The EWP & Fan Digital Controller (part no. 8020) is primarily designed to run the EWP with the added function to switch on and off your Electric Fan, which saves you the cost of having to purchase an additional electric fan switch. If you are not using our EWP then we would recommend against purchasing the EWP & Fan Digital Controller as you primary fan controller as you can't independently set the cut in temp for the fan. The EWP & Fan Digital Controller is programmed to switch on the fan at 3°C above the EWP temp setting. For a fan only application we would recommend using either our Mechanical (part no. 0401) or Electric (part no. 0402) Thermatic fan switch and wire direct to the battery so the fan will run on after engine shutdown.

Question No. 6
When installing the Thermal Switch Adaptor Kit (Part No. 0409), I found that my vehicles hose size is larger than 35mm, what should I do in this circumstance?
The 0409 kit comes with adaptors to suit inside diameter hose size of 30-35mm, if you have 36-42mm inside diameter hose then you need to use the 2 rubber sleeves over the adaptor to allow for the larger hose which are included in your kit. If you have 42-51mm inside diameter radiator hose, you can contact us and we can provide you with larger rubber sleeves to accommodate your needs.
We do not keep records on each and every vehicles top radiator hose dimensions and therefore leave it up to the customer to measure their radiator hose size and advise.

Question No. 7
I would like to place the Thermal Switch (Part No. 0401, 0402, 0404) unit in the vehicle’s cabin rather than under the bonnet. Is this possible?
No, Davies, Craig Thermal Switch (Part No. 0401,0402 & 0404) must be mounted in the engine compartment near the radiator.
The EWP/FAN Digital Controller (Part No. 8020) should be mounted inside the vehicle cabin to access the controls and feedback information away from direct sunlight and should not be exposed to excessive heat.

Question No. 8
Do I really need to have the Digital Controller?
The Digital Controller (Part No. 8020) is Davies Craig’s recommended method of operating both models of the EWP. However it’s not the only method of control.
If the EWPs are to be used in motor racing or drag racing, you can run the EWP continuously, due to the extreme amount of heat produced under those conditions. If your race engine runs too cold, upgrade to the Controller.
The EWP may be used with a Davies, Craig Thermal Switch (Part Nos. 0401 and 0402) as an auxiliary pump. If the EWP is the only pump in the engine it should not be run with an on/off thermal switch like a radiator fan. Your engine needs some flow all the time or hot spots will form outside the cylinders.

Question No. 9
Can I use the EWP & Fan Digital Controller to run my Thermatic Fan Only?
The EWP & Fan Digital Controller (part no. 8020) is primarily designed to run the EWP with the added function to switch on and off your Electric Fan, which saves you the cost of having to purchase an additional electric fan switch. If you are not using our EWP then we would recommend against purchasing the EWP & Fan Digital Controller as you primary fan controller as you can't independently set the cut in temp for the fan. The EWP & Fan Digital Controller is programmed to switch on the fan at 3°C above the EWP temp setting. For a fan only application we would recommend using either our Mechanical (part no. 0401) or Electric (part no. 0402) Thermatic fan switch and wire direct to the battery so the fan will run on after engine shutdown.

Question No. 10
I have just purchased a THERMAL SHITCH & RELAY, Part Number: 0404 and it is not turning the fans on regardless whether its set to high or low?
When you first install any thermal switch, make sure you run the car engine up to temperature or at least 110°F before trying to adjust the temperature switch. Please use the instructions for the correct set up procedure. Should the fans still not come on after instructions have been followed, please contact customer services for further assistance.

Question No. 11
Can I run the Digital Controller on a Vintage Car without suppressed ignition leads?
No, your old wire leads will cause the controller to play up. You will need to install new leads to allow the controller to work.

Question No. 12
My Electronic Thermal Switch Sensor (Part 0402) does not seem to be working?
A common error during the installation process is to push the sensor all the way through the radiatior so that the end is protruding through the otherside, meaning the the sensor end is not in the radiator fins. You should use the quick mount as a backstop.

Question No. 13
I have purchased an Electronic Thermal Switch (Part 0402) but could not find any instructions about what should be done with the blue wire in the single use thermatic only section?
The blue wire from the electronic switch (part# 0402) is only required if you are running a second fan. This would normally go to the second fan relay. If you're not running a second fan then the blue wire is not required and you can tape it up or cut it off.
If you have everything else wired up correctly as per your single fan wiring set up and the fan doesn't work when you adjust the temp fully either direction with the engine temperature at least 40°C then you may have a faulty switch. We suggest before coming to this conclusion to re-check all the wiring and contact points, check the fuse in the orange wire to make sure it isn't blown and also ensure your engine is warmed up before the fan will activate. If you think you have a faulty switch then take it back to your retailer with your receipt as all our products have a 2 year warranty.

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