Many times not all graphics are stored by the WaybackMachine, so if there are graphics missing from the following VFAQ, please don't email me about them (unless you are emailing me to tell me you have a copy of the missing graphic you can send me).

If you know the original author of this VFAQ, and have their contact info, please have them email me if they have any missing info to add, have the VFAQ at another site I could not find, or wish to have it removed from my site.

2.0L Turbo Cooling Fan Relay Bypass Mod (2G vehicles)

This modification provides a bypass wire and switch around both the engine fan relay and the AC fan relay that does several things:

1. It enables the user to override the ECU's "fan OFF" signal, by switching ON the control switch, so that both fans energize, whether or not the ECU wants them on, and whether or not the engine is running.
2. It modifies the system so that whenever an engine "fan ON" signal is present or an AC "fan ON" signal is present, both fans turn ON.
3. It maintains engine cooling protection no matter what the position of the control switch is. You cannot disable either fan using the switch. If the ECU wants either fan to turn ON, they both turn ON, period.
4. A negative aspect of this mod -- if you forget to turn the control switch to OFF after shutting off the car, both fans will continue to run until the switch is turned to OFF or until your battery is completely discharged.

You'll have two primary work areas when doing this job. First, you'll start in the fuse box, installing three wires (16 gage). Then you'll route two of those wires into the car through the rubber boot surrounding the steering column and install a toggle switch between them to control the current running to the fans.

Shown below is a diagrammatic representation of the final configuration.

PROCEDURE:

1. Disconnect the car's negative battery cable.
2. Remove the engine fuse box cover on the passenger side of the engine bay.
3. On the bottom row, the one closest to the front of the car, there are six relays (black in color). The ones in my car are labeled "MR 122409 12V OMRON MADE IN USA 7198A11B". Pull upward to remove the second from the left (the engine fan relay) and the fifth from the left (the AC fan relay). Note that each has four prongs. Here's how the stock system works. The upper two prongs are the main power terminals for the fans, and the lower two prongs are the ECU signal terminals. When 12V is applied by the ECU to the lower two terminals of the engine fan relay (at a coolant temperature of about 210 degrees F), the relay will trip to shut an internal contact, which allows current to flow through the upper terminals to the engine fan to start it. When the ECU has decided that the engine is cool enough, it will turn off the engine fan by removing the 12V signal to the lower terminals, opening the internal contact, and breaking the connection between the upper two terminals to remove main power to the engine fan. The AC fan is controlled by the ECU in the same manner. If the air conditioner is turned on, the ECU turns on both fans, irrespective of engine coolant temperature.

4. In the holder for the AC fan relay, insert the end of a 16 gage wire into the upper most jack. Do the same thing for the jack just below it. Route both wires through the rubber boot surrounding the steering column into the car. Once they're in the car, connect the wires across a toggle switch and mount the switch in a convenient location (see diagram below). This will be your ECU override switch that will enable you to turn on the fans independently of the ECU. Leave the switch in OFF position, for now.

5. In the holder for the engine fan relay, insert a 16 gage wire into the second jack from the top. Connect the other end of that wire to the same jack on the holder for the AC fan relay. See diagram below. This wire connects the two fans so that they always operate together as a pair, both ON or both OFF. If you omit this entire step, you'll have control over the AC fan only.

6. Gently reinstall both relays into their original positions. It will take a little pressure to get the prongs all the way back into place due to the wires that you've just inserted into the jacks. The wires take up some of the space that the prongs need to slide back into the jacks. Do not force them. If you can't get a relay into place with moderate pressure, remove the relay and spread the wire ends so that they lay flatter against the jacks, then try again.

7. Inspect your installation to make sure that no wire ends contact any electrical conductors that they should not contact. You could blow a fuse if this is the case.

8. Reinstall the cover on the fuse box.

9. Reconnect the negative battery cable.

TESTING THE INSTALLATION:

1. Turn the toggle switch to ON. Both fans should energize. Turn the switch to OFF; both should turn off.
2. Start the engine. Leave the air conditioner off. If coolant temperature is less than about 210F both fans should be off.
3. Turn on the air conditioner. Both fans should turn on. Turn off the air conditioner. Both fans should turn off.
4. Leave the car running with the toggle switch in the OFF position. You can either idle the car or drive around while watching your engine temperature gage. At the temperature at which your engine fan normally energizes, both fans should energize. At the temperature at which the engine fan normally de-energizes, both fans should de-energize.
5. After both fans have de-energized, override the circuit by turning the toggle switch to ON. Both fans should energize even though the ECU expects them to be OFF at this point.
6. If all the above checks work, you're done.
7. CAUTION: Don't forget to turn the toggle switch OFF whenever you turn off the car and no longer want the fans running. If the toggle switch is left in the ON position, the fans will continue to run, even if you don't have the engine running.

This "How To" was created by Todd Hayashi, member of Club DSM - Hawaii Chapter. The modification was easy to install and works well in my car. I cannot guarantee that you'll install it properly. I've described the installation to the best of my ability. Without pictures, it's not possible to give you a complete view of all aspects of the job. Those with experience in basic electrical circuit theory will find this modification to be very easy to perform. For those who have never worked with electrical circuits and have little knowledge of the basics, get someone with some experience to help you.

THE BOTTOM LINE: Do not blame me if you mess up your car when attempting this mod. Anything you choose to do to your car is at your own risk.

E-mail questions or comments to me at dsmanimal@hawaii.rr.com