The installation of your coolant pump is beyond the scope of this document, however, here are some basic considerations.

• There should be no thermostat installed, the electric coolant pumps are most efficient when allowed to run with no restrictions.
• This controller must be the only device connected to the temperature sensing thermistor.
• The thermistor should be placed as close as possible to the coolant output (upper radiator hose) of the engine.
• The battery should be disconnected while making electrical connections to the controller and other devices.

The following wiring diagram shows how to connect the pump, fan(s) and controller.

Equipment List:

• This Coolant System Controller
• 2 12V relays capable of running the coolant pump and fan(s), with harness; for example
• 12V coolant pump (sized by motor power or diplacement); Davies Craig offers a large variety
• 12V radiator fan(s) (enough to keep it from overheating while the car is sitting still on a hot track)
• 10kOhm at 200F thermistor with wire and connectors, for example: Davies Craig DC0465
• Optional 12V Overheat warning lamp (<250mA or a third relay)
• A device for measuring the engine temperature (a dash gauge or ECU reading will work)

The controller is not weather resistant and needs to be installed in the cockpit, preferably in a place that the driver can see the LED’s. The connectors on the controller are screw-clamps and work best with just twisted bare wire.

Calibration:

This controller is designed to manage the temperature of the engine by switching the pump between two control modes: Pulsing and On. The temperature of the changeover is adjustable. The characteristics of the pulse are also adjustable. The Fan control and Overheat warning also switch between two modes, Off and On. The temperature set point for these On modes is also adjustable. There are LED indicator lights, Green to indicate that the control circuit has power, Blue is for Pump, Yellow is for Fan and Red is for Overheat.

The adjustment of the Pulse has two elements, the On-time and the Off-time. The On-time is used to stir the coolant to prevent hot spots while the engine warms up. The Off-time is when the engine actually warms up.

Pump Pulse:

The setting for the On-time should only need to be adjusted once. Use V10 (12 turns) to adjust this setting. This timing should allow the pump to come up to full speed, then stop immediately, there should be very little movement of the coolant. During warm-up, the coolant in the radiator should stay in the radiator. A 150 liter/min. pump will transfer the entire contents of a radiator in 3 or 4 seconds. So the On-time should normally be less then a second. There is no hole in the housing to make this adjustment.

The next setting is the Off-time (V7 – 1 turn). This is the time that the engine is actually warming up. This setting may need to change, depending on ambient conditions. There is a hole in the housing to accommodate this adjustment. We’ve found that a setting between 4 and 8 seconds is enough to keep the engine warm when the ambient temperature is above 50F. This may be different for your particular configuration.

Pump On:

Now that the engine can warm-up, the temperature set point needs to be adjusted. With the controller installed, start the engine and let it warm up. When the engine gets close to normal running temperature, adjust V4 (12 turns, also labeled “P” in the “T adjust” realm) to change the temperature that Pump changes from Pulse mode to On mode, this will determine the operating temperature of the engine (usually around 190F).

Fan On:

Keep the engine running, the temperature should keep rising, there is no air going through the radiator. The Fan set point adjustment (V8 – 12 turns, also labeled “F” in the “T adjust” realm) is similar to the pump adjustment, Fan should come on below the boiling temperature of the coolant, but at a higher temperature than the pump set point (around 200F).

Overheat On:

Your cooling system is now under control, the last setting is for the Overheat warning. Reminder: the battery must be disconnected when changing the wiring to the controller. The Overheat adjustment is done with the engine not running. To help make this adjustment, there is an on-board thermistor emulator (V3 – 25kOhm – 12 turn).

• The housing must be removed (there is no hole for V3)
• The thermistor must be disconnected at the T+ connector
• The jumper, JP1, must be shorted
• Optional, disconnect the Pump, Fan and Overheat relay wires

Adjust V3 until Pump (blue LED) transitions to On mode, then count the number of turns needed to turn Fan On (yellow LED). Keep turning V3 the same number of turns previously counted, this is now emulating an overheat temperature (around 210F). Adjust V1 (also labeled “O” in the “T adjust” realm) to transition the Overheat (red LED) to the On mode.

Transition to Off or Pulse:

There are also adjustments for the lower setting of the transitions from On to Off or Pulse (technically — the hysteresis of the set point). The Pump adjustment (V5 – 1 turn) is the transition temperature from On mode to Pulse mode. Adjusting V4 will change the set point of V5, however, adjusting V5 will not change the V4 setting. V6 and V2 have a similar function for Fan and Overheat. This should normally be set as high as possible. If there is a problem with excessive cycling, these can be adjusted lower. There are no holes in the housing for these settings.

Testing:

Disconnect the battery. Remove the short on JP1 and reconnect the thermistor (and relays if needed). Install the housing, making sure the wires are secure to the slotted tabs. Reconnect the battery. Time to hit the track. If the engine fails to reach normal operating temperature, adjust V7 to increase the Off-time. There is a hole in the housing for this setting. If needed the short on JP4 can be removed to increase the range of the Off-time (8 to 14 seconds).

The normal operation at moderate ambient temperature is for Pump to slowly cycle between Pulse and On mode. Fan and Overheat should not transition to On. Although, Fan may turn on for brief periods during high loads.

After-run:

After-run is a feature that will activate Fan and Pump (optional) after the ignition is turned off. The amount of time (10 to 270 seconds) they run is determined by the setting V9 (1 turn). There is a hole in the housing for this setting. JP2, when shorted, will disable After-run. JP3, when shorted, will enable Pump during After-run, otherwise only Fan will be enabled during After-run.