You may never have let it get hot enough.
--------------------------------------------
Cooling Fan Motor Control

The PCM controls the cooling fan motor by controlling the cooling fan=20
relay. The PCM controls the cooling fan relay by controlling an internal=20
driver that pulls the relay coil circuit to ground. When the relay coil=20
circuit is pulled to ground, the switch side of the relay closes=20
allowing current to flow to the cooling fan motor.

The PCM turns the cooling fan relay ON based on the reading from the=20
engine coolant temperature (ECT) sensor. The ECT sensor is a thermistor=20
that varies resistance according to changes in engine coolant=20
temperature. The PCM supplies a 5 volt reference through a pull-up=20
resistor to the sensor, which is connected to ground. When the sensor is=20
cold, it has high internal resistance, high signal voltage at the PCM.=20
As the sensor temperature increases, its resistance decreases, a low=20
signal voltage at the PCM. The PCM uses the signal voltage to determine=20
the engine coolant temperature.

Under normal operating conditions, the cooling fan motor operates=20
whenever the ECT is greater than 105.5=B0C (222=B0F) or the A/C relay is=20
commanded ON below 113 km/h (70 mph). The cooling fan motor will turn=20
OFF when the temperature drops below 100=B0C (212=B0F). If the engine is=20
turned OFF and the ECT is above 107=B0C (225=B0F), the cooling fan motor ca=
n=20
run up to 4 minutes or run until the ECT drops below 107=B0C (225=B0F) with=
=20
the ignition OFF. If a low/high ECT circuit fault resulting in DTC P0117=20
or P0118 is set, the PCM will command the cooling fan relay ON to=20
protect the engine and transaxle until the condition is corrected.
--------------------------------------------
If you know what the resistance of the ECT sensor is just below 210 and=20
above 222 you can use resistors to simulate those values. If the fan=20
kicks on with the simulated 222deg resistor and the gage on the dash is=20
just above 2/3rd's then you know you're fine.

I couldnt find these values so I cant tell you but I know they're=20
somewhere.




In article .com>,=20
says...
> Thanks Kirk, at first I thought the same thing.
>=20
> But I was able to confirm that it was not the motor by shorting across
> contacts 87 and 30 of the fan relay. The fan would start up every
> time. To make a long story short, since I had satisfactorily tested
> the fan, relay, fuses, temp sensor and almost everything else I could
> think of, that only left the computer, or the wiring between the sensor
> / computer / fusebox. (I bet it's probably the computer.)
>=20
> But since I didn't want to replace the expensive computer or tear apart
> the wiring harness, I installed a secondary 30 amp relay with contacts
> 87 and 30 in parallel with the original one. Then, I just put a
> lighted switch in the dashboard which powers this relay and turns on
> the fan immediately (regardless of whether the factory relay is being
> turned on).
>=20
> The mod is all installed with removable connectors. So if I manage to
> fix the problem which stops the computer from turning on the fan, I can
> pull the whole secondary circuit out and return it to stock condition
> in 5 minutes, except for the small hole where the switch is installed.
> And it's a cool looking switch. :-)
>=20
> The other thing I was thinking I might do is wire up a voltage detector
> circuit to the engine temp sensor in parallel with the computer. I
> might be able to just create my own simple automatic fan control
> circuit so that Mom doesn't have to remember to flip the switch in slow
> moving traffic. Hmm...
>=20
> -=3DIvan
>=20
>=20