How to Install DIF PWM/Dual Fan Controller on Nissan 240sx

Since this is an electrical install, disconnect the battery by removed the negative terminal.

Removing the battery provides more room to work.

Next, remove stock intake tubing if your car has it. This will allow easier access to the coolant temperature sensor on the intake manifold.

It is recommended to intertwine the white and grey wire from the DIF controller together. (twisted pair wiring)

This will help protect against electromagnetic radiation/noise from other components in the engine bay.

One way to do this is to insert one end of the wires into a cordless drill; then power the drill until the disred tightness is reached.

You can refer to the write-up for the DIF Dual Fan Controller install, which is similar.

Image 3 shows what the DIF Dual Electric Fan Controller comes with.

However, note that there are a few key differences, namely in connecting to the fan motors and programming the unit.

Placement of Fan Controller: I chose to mount the fan controller in front of the battery behind the radiator support.

This location is convenient for wiring and re-configuring the DIF controller (if necessary)

Feel free to mount it anywhere you find to your liking that is away from heat sources.

A small strip of double-sided tape can be attached to the bottom of the fan controller for simple mounting.

It is easier to attached the tape to the fan controller and leave the other side of the tape unpeeled.

This will allow moving the DIF controller to a more suitable spot/orientation later during the install.

For my install, I chose to modify an L-bracket and mount the controller with screws to the radiator support.

Electric Fans: Connect the positive wires of the fan motors to the battery.

Make sure you use the proper AMP fuse for your fan.

Connect the negative wires of the fan motors to the two large white negative wires coming from the fan controller.

Fan Controller: Connect the large black negative wire of the electric fans to a clean chassis ground area or directly to the negative terminal of the battery.

If using a chassis ground, it is recommended to sand the area down to bare metal and using dielectric grease, which will help prevent corrosion and moisture build-up.

The large white negative wires of the fan controller should already be connected to the negatives of the fan motors (from above).

Image 2: Diagram of wiring for the DIF Dual Fan Controller.

The coolant temp sensor is located on the upper intake manifold near the upper radiator hose inlet.

There are two temp sensors in the engine bay - one (1 wire) for the dash, and one (2 wire) for the ECU.

The correct one to tap into is the 2-wire ECU sensor. On the KA24DE, it can be identified by a red 2-wire plug held on by a clip.

Remove the clip and pull the plug. Once the plug is out, use a razor blade to remove some of the harness cover shielding to allow room for tapping the wires.

The blue wire w/tracer is the positive coolant temp. wire. The black wire is the negative coolant temp. wire.

Connect these wires to the S+ and S= terminals on the fan controller. After shielding has been removed, you can either tap the wires with t-taps, or strip and solder the connection.

Once the wires are tapped, continuity should be verified with an ohm-meter. Place one prob into the sensor plug and the other onto a metal part of the t-tap.

If there is no connection, 0 will be displayed; if there is continuity, a 1 should be displayed.

The BA wire for the fan controller should be connected to the battery or other 12v signal.

If you don't want the "cool-down" feature, connect the BA wire to an ignition source. The supplied fuse and fuse holder should be used with this wire.

Connect the IGN wire from the fan controller to an ignition source. I chose an orange wire w/a blue tracer located near the battery. I verified this with a voltmeter.

If you want to use the a/c feature (minimal 50% duty cycle fans when a/c is on), you must connect the AC wire to an a/c source.

There are a couple of plugs you can tap into near the battery and a/c condenser.

For the manual switch, you will need to connect a switch that is connected to a ground and the MA terminal on the fan controller.

For all connection points, it is recommended to install heat shrink tubing or at least electrical tape to prevent any shorts in the future.

The fan controller comes unprogrammed. If your fan controller is unprogrammed, it will just show a green light for several seconds, then turn off & repeat the cycle once the car is on.

To program the fan controller, you need to move a few wires around to engage "programming mode."

Turn the ignition off. Wait 20 seconds.

Disconnected BA wire. Disconnect AC wire if you have it.

Move IGN wire to AC terminal. Ground the MA wire.

Turn the orange knob to the appropriate position (E for Nissan- this will make the fans cycle 4 times when controller is reconnected)

Turn the key to the "ON" position.

Reconnect the BA wire.

At this point the fan controller should flash the LEDs and pulse the fan(s) to confirm the settings. It will continue to repeat this cycle.

After verifying the number of pulses, disconnect the BA wire.

Turn the ignition off. Wait 20 seconds.

Move the IGN wire back to its original position.

Unground/disconnect the MA wire.

Reconnect the AC wire. Reconnect the BA wire.

When the fan is working properly, the LED should alternate between green and orange. When it is cooling down, it will flash red.

Configuring the DIF Fan Controller: The optimal operating temperature for KA's is approximately 160f to 190f.

Since this particular vehicle has a Nismo thermostat installed, which opens thermostat at 143.6F instead of stock 169.7F, I set the fants to turn on at 158F (Letter C) for track days.

For stock thermostat, I would probably set it around 170F to 178F, (F to H on the knob).

Testing the Fan Controller: Once everything is reinstalled and setup, start the car and allow the engine to warm up. The LED should be alternating between orange and green, as described earlier.

Depending on your particular setup, location, and weather, it may take a while before the fans activate.

A simpler way to test the fans is to use the manual switch and/or set the adjustment dials to a lower setting, so that the fans turn on earlier.

Various LED status video of DIF Fan Controller: Hopefully this video will help some installers recognize the state their fan controller is in.

Video of DIF PWM Fan Controller in various states. It covers: Not programmed, programming state, normal operation, cool-down feature.