The Following procedure can be used to check see if the GEM module is getting signals & sending from/to the attached systems.

Things To Check Before You Start.
> Switch OFF the ignition.
> Switching OFF all other electrical systems.
> Apply Handbrake.
> Engage Neutral (Manual) or P (Park on Automatics).
> All Doors are Closed.
Once thats done you can continue ( note - If the alarm activates this procedure will not work )

Self Test Activation Procedure.
1.Press & hold the rear window heater switch.
2 While holding the rear window switch down turn on the ignition & then release the rear window switch.
( If done correctly a signal sounds & the indicator warning lights will illuminate to show your now in the test mode )

Input Signals Testing.
Now to test the systems put the windscreen wipers into the OFF position to enable the input signal test mode & then activate any of the following controls to test there connection to the GEM module ( An audible alert & the indicator warning lights will flash on each signal the GEM gets )
> Direction Indicators ( Left / Right ).
> Hazard Warning Lights.
> Sidelights.
> Windscreen Intermittent Wipe.
> Windscreen Wash/Wipe System.
> Rear Wiper.
> Rear Wash/Wipe System.
> Doors Opening/Closing.
> Remote Boot Release Switch ( Centre Dash Console ).
> Boot Release Switch ( On The Tailgate ).
> Boot Opening With A Key.
> Lock Key On The Remote. *
> Unlock Key On The Remote. *
> Boot Release Key On The Remote. *
> Bonnet Open/Closed.
> Heated Rear Window.
> Heated Windscreen.
> Ignition On.
> Automatic Transmission, Lever Position P.
* - The Ignition Key Must NOT Be In The Ignition During This Test

Output Signal Testing
Put the wiper switch into the Intermittent setting.
Press the Rear Window heater switch to activate or de-activate the output signals in the following order.
> Front Wipers ( A signal sounds & the indicator warning lights flash when the park position is reached ).
> Rear Window Heater.
> Interior Lights ( The switch for the interior lights must be in the 'door open' setting ).
> Door Ajar Warning Light on the Dash.
> Rear Window Wiper.
> Windscreen Heater ( When the engine is running only ).

Exiting Test Mode
The Test Mode is exited automatically if no buttons are pressed for around 20 seconds or if the car is driven ( This de-activation is indicated by 3 signal sounds & indicator warning lights flash's )