RHS Fan on, always??

[loony888]

G,day guys and girls, i usually hang out on my local board but i'm hoping for some input from someone who might know......
my 03 S4R has a D/P ECU and has just started to run the rhs fan whenever the ignition is on. if i swap my std ecu it does the same thing...
i know the ecu's fail but didn't expect my std one to do the same thing and was hoping it would work fine so at least i would have confirmation.
so, would it be my temp sensor? any way of testing it?
i know the fans come on at different times, and frankly, unless i've been stuck in heavy traffic it never needs them, i also know they are controlled separately by the ecu and are grounded in conjunction with the ambient temp/pressure sensor behind the headlight, i've checked the wiring externally and it all looks ok, i think both fans run off the one relay so that is fine too, yes?
please help, i don't want to have to buy a new ecu but if i do i need the DP one from the full kit which it's part number is 96445304B, i don't yet know the actual ecu part number i need. i do now, 96511503B
hopefully someone will
a. have the ecu i need?
b. confirm how i diagnose the actual problem?
or c. offer me a ludicrous price for my baby so i can buy a newer one........

Thanks for looking and especially thanks if you can help!
paul.
p.s i did a search, no luck.

[Howie]

Disconnect the sensor.  Fan off?  The sensor is at fault.

[Speeddog]

There's two coolant temp sensors, one is for the instrument panel display, the other is for the ECU.

Yes, both fans are controlled directly by the ECU, IIRC they're supplied with 12v and the ECU controls the ground.

Not really a good sign that one is running constantly.

[loony888]

that's correct speeddog, i've swapped the sensors over and confirmed the sensors are ok.
waylon from houston super bikes is concerned there's an earth issue in the wiring loom somewhere..........oh joy

[Speeddog]

It could be that the 'ground' wire between the fan and the ECU may be shorted to ground.

[loony888]

It could be that the 'ground' wire between the fan and the ECU may be shorted to ground.

that seems to be the common opinion, but, i ran the bike up to 104 deg C and the lhs fan didn't come on at all (it works, i tested it) the rhs fan is on all the time. on the lhs there is no power at the loom plug with the ignition off or on 35k ohms resistance to ground.
rhs fan has the same resistance to ground at the loom plug and has 12v ignition off and on, between active and ground i get 2.5v. any ideas??

[loony888]

it was shorted to ground in the loom between the frame and the air box top right hand corner. it is fixed, and the lh fan not being powered up is due to the fact i'm running an S4 d/p ecu on my S4R.
off to houston super bikes for a reflash of my std ecu to suit all my mods.
thanks speed dog, thanks howie.

paul.

[Howie]

Glad you are up and running.

[Speeddog]

Glad you got it sorted.

There are a few wiring differences between '01 S4 and '02 S4, the fan setup is one of them.

IIRC the '01 has an external fan relay, so both fans are controlled by one ECU input, and the '02 controls each fan independently and directly, no relay.

I'm pretty sure that the 1st gen S4R is set up like the '02 S4.