I posted this on the bad idle thread for you but I'll copy it here to.
ok here is how to check for codes
( should be in your gregory's car guide thing)
over near your brake booster on the drivers side right in the corner you will have to plugs.
One is a small grey plug with 1 wire attached the other is a large black plug with a total of 6 connections but only 3 wires running in to the plug.
To check your base timing (that is your timing with out ECU assistance that can change it by +/- 30 degrees) simply connect a wire from the input connector (the small grey one) to the negative terminal on the battery.
To check for ECU codes:
1st to check for constant codes.
Place a wire from the output connector to input plug no 2 ( they are numbered on the connection) then run a test light from output (black connector) 4 to the positive connection on the battery.
Then place the car in to ignition the car will then read out codes like this.
flash, 2 second pause, flash (that's code 11 meaning it's all a ok)
then a six second pause then flash, 2 second pause nothing then six second pause then flash, 2 second pause, flash. (so thats 10 and then 11)
so you can gather from this that the codes will be read as follows.
first number than 2 second pause then second number. Then six second pause then display second code and so on and so forth.
This will spell out the codes for a constant fault.
repeat the same procedure with the car running to find and intermittant faults. Intermittant faults are issues that have been detected while the car was running but may not be happening at this very moment.
Great for finding a problem.
If you want to know what the codes mean buy the manual or post them up here and I'll tell you.
Breathe! It's only the internet....