(this is not my own work, btw, but is legit)

ECU is located directly behind the kickpanel in the left hand foot well:

-remove the three bolts securing the ECU to the bulkhead, floor and lower dash -carefully wiggle the ecu from it's position -don't damage the wiring harness

-turn the ecu around --the face farthest from the wires has a small dial and a LED --( later models have 2 led's)

-find a screwdriver small enough to turn the small dial...

-turn the ignition on ( but don't start the engine )

-the red LED will start to glow...

-CAREFULLY turn the small dial CLOCKWISE fully...

-the LED will go off...

-then turn the LED fully anticlockwise...

-the LED will start to flash...

-long flashes then short, repeatedly, until you switch off the ignition or start the car --if the sequence is five long then five short flashes, the code is 55, which means all is OK --3 long then 4 short means a faulty knock sensor, etc (see codes below).

you want a "55" = ok.

Codes:

11 Crankshaft position sensor
12 MAF sensor circuit
13 Coolent temperature circuit
14 Vehicle speed sensor circuit
21 Ignition circuit
31 ECU (ouch!)
34 Knock sensor
43 Throttle position circuit
45 Injector leak
51 Ignition circuit
54 Auto signal to ECU
55 All OK

 

Or you could get a consult interface and datascan software, the interface plugs into the consult port that is in the fuse panel in the drivers footwell. I bought mine from an Australian company and it was 50GBP delivered, that includes the software:

http://www.plmsdevelopments.com/consult_if.htm