MR2 Engine Cooling Fan Modification
From: "Kostas G. D. Chryssos " (uunet!compulink.gr!sv1bt)
Date: Sun, 28 Jan 1996 22:45:25 +0200
Subject: Re: MR2 Engine Cooling Fan Modification
If you want to modify the operation of the Engine Cooling Fan, which
provides cooling to the inter cooler as well, in order to make the operation
of the fan manually selected, regardless of the under-hood temperature here
is an easy way to do it.
1. Locate in the engine bay the fuse/relay box. Looking into the bay from
the driver's side (left hand drive cars) it is located between you and the
engine somewhat to the right, lift the cover and note two connector plugs.
One towards you, (first plug) somewhere in the middle of the box, to the
left of the EFI Relay, and one towards the engine, (second plug) to the top
of the box, left of the three fuses (top EFI fuse, Vent fuse under and
ECU-IG fuse under vent fuse). Go to the second plug and locate pin no.3
where a black/red wire cones out from the top. Pin No. 3 is the one on the
bottom line ( towards you and left from the Vent 20A fuse) extreme right
corner pin of the plug. (You can work without removing the plug.)
2. This wire (black/red) is the wire taking ground from the Engine Cooling
Fan ECU to the fan relay, is normally on - that is it provides a ground to
the relay continue sly, the relay being energized in the normal condition
but the fan is OFF since the relay contacts in the energized position
disconnect the fan from power.
3. With a wire cutter, cut this wire making sure you leave half of it on the
plug and half of it on the harness...take care since the overall length of
this wire is not much.
4. You can start the engine, after cutting this wire and notice that the fan
is now running. If not, you have cut some other wire instead. Go back and
double check.
5. With the engine switched off, connect a pair of wires to the two loose
ends, making good electrical contact and insulate the joints. You can use
electrical crimping splices, you will need a crimping tool for this, but you
do not need additional insulation as those splices are insulated, use the
red ones, this is the smallest diameter, since the wire is rather thin.
6. Route the two wires (preferably a pair with overall insulation) out of
the fuse/relay box (there is some free exit space on the bottom of the box
but it is a little hard to locate. Use a flash light from the outside/under
and look from the top to locate the opening).
7. Once the wires are out, route them through the fire wall. To do so you
will have to remove the left side panel behind the driver seat, the center
console and the armrest console as well as the top cover of the loudspeaker
box. First remove the top of the loudspeaker box, lift the end towards the
seat, there are three snap plugs there and from the inside unscrew the three
screws under the hinge and remove the cover. Then check on the right side of
the exposed area there are two plastic plugs that hold the side panel's
bottom portion. Remove them. Also lift the plastic gutter of the drivers
door rear end slightly to free the side panel and pull the side panel off
starting from bottom to the top. There are six or seven snap plugs to get
loose. Hinge the top end out as there are two teeth going underneath.
8. Remove the rest, there are 4 screws into the rear console, two inside the
top box and two inside the bottom one. Do NOT remove the screws which are
outside the console sides. Lift the console out. Then remove the 4 side
screws on the armrest, remove the gear shift leather cover upwards and the
plastic cover after lifting from rear towards the front. Hinge the front
out. Then remove two screws exposed up front. There are 6 screws all
together to remove on the armrest. Lift the armrest off.
9. Move the seat all the way up front. Look to the fire wall carpeting and
lift it from bottom to top. You will not remove it from the top, just lift
it upwards to expose the duct (hole) with the wires passing to the engine
bay. Find a way to hold the carpet fast. Remove an oval sound proofing patch
and lift the cable harness from a fastener just under the feed-through hole
by pushing on the clip. Put a blunt screw driver where the rubber cup meets
the metal of the fire wall and work the rubber cup out towards you. It works
as a big rubber grommet with a dent for the metal. Once removed, unfasten
the electrical tape completely, making sure that you do not remove the
plastic adapter clip which holds the harness to the fire wall. If so, mark
the place to re-install it. Once you have removed the tape, you can easily
pass the wires through the center hole of the big rubber grommet. I suggest
to pass any additional wires that you would require for other mods etc so
that you will not have to do this again ( EVC etc).
NOTE: I have noticed after completion that it is MUCH easier to route the
wires from cabin to engine compartment than the opposite, especially if you
have NOT removed the air filter box. So the wire laying is better in reverse
order.
10. With the wires through, re-tape the rubber grommet push it through to
fit in the fire wall, move it sideways to make sure it is properly located,
clip the plastic fastener to hold the harness fast to the fire wall, replace
the oval pad and route the wire to the armrest up front via the rear of the
speaker box, push it there all the way to the bottom. Then pull down the
mat, make sure it fits properly behind the strap fasteners, re-install the
side panel working from top to bottom, (I used some rubber glue to hold the
snap plugs in place), do not forget the two plastic plugs on the bottom side
and then fit the speaker box cover, three screws there and flip/snap it
closed (three snap plugs).
11. You can install the switch on the plastic cover around the gear shift
lever or you can route it to the side of the fog lights switch where there
is space provided for two more switches. Get a stock fog switch and connect
it there. Make sure that you wire it so that normal should be closed switch
(wire ends sorted together) and activated should be open switch (wire ends
open).
12. Re-install the remaining. You can now manually operate the engine
cooling fan which will also provide fresh air to the inter cooler. This
helps on boosts at low speed.
It should be here noted that the panel light does NOT come on with this
modification. It will come on though if the engine temperature rises and the
cooling ECU takes over. The stock operation is still active as long as your
switch is in the auto (not manual) operation providing a connection between
the two wires.
If one wishes to have the light ON as well, then the wires have to run all
the way to the ECU instead of the plug in the fuse/relay box. There the two
wires will connect a 800 ohm resistor between terminals 5 (L) and 6 (L-O)
of the cooling fan ECU (located next to the engine ECU). I did NOT make this
mod as I wanted to avoid getting additional wires into the engine ECU
compartment in fear of Radio Frequency Interference to the engine ECU from
my high power ham system on board. I have installed the switch just behind
the gear shifter along with the re-located fog lights switch and the antenna
control switch. I have installed the HKS EVC + Timer control boxes at the
original location of the fog light switch.
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(Kostas G. D. Chryssos Ph.D.)
30,Ikarias str. Glyfada GR16675, Athens, Hellas
Tel: xx-301 9628212, Fax: xx-301 9628539