Help req'd, 4,2 cooling fans not working - suspect ecu?

[rswheelnut]

Hi, I'm hoping someone can assist...

Recently the cooling fans on my 1996 4.2 stopped working.
Was driving fine but then when parking i noticed the temp starting to rise above normal so cut the engine immediately.
Garage has tested the car and have advised they believe it to be the ECU.
If remove the temp switch the fans should always run but don't.
Fuses and relay ok. If power up the system the fans come on, so the actual fans and connectors etc must be ok.
Garage took cover off ecu and cant see any obvious dry joints, and there's no dampness or anything on or around the ecu (car is dry stored and not used in rain anyway)

Is it common for fans not to work due to ECU?
Is there someone i can send the ecu to for checking and fixing?

Any help would be much appreciated....

[rswheelnut]

thanks guys.
as theyre only cheap i'm now replacing the coolant temp sensor (with a bosch one) and also the relay - although the relays were swapped over before with no change so thats an unlikely one but doesn;t do any harm to eliminate.
may also replace the fan connectors for good measure.
will see if that makes a difference.

if still suspected as ecu, i guess an alternative may be to add in a new temp sensor somewhere to seperately power the fans. or add a fan switch, but i don't want to remember to turn things on and off

[rswheelnut]

replaced temp sensor and whilst doing so i noticed the connector onto it wasn't in particularly good shape so also replaced that. Now seems ok!
thermostat seems to open about 80-85 degrees
first fan comes on at 90 degrees
second as it approaches 95 degrees and it never seems to go above that even stationary, revving and with things like air con on.

result!

thanks everyone for their input. i'm glad no ecu issue!