EGT sensor/ instrument panel warning light
 

I have a 1995 wrx wagon. Recently upgraded the turbo to td05 and swapped the original 3B Ecu for a Z4. Really pleased and car going great. The Egt warning light now doesn't come on when key set to run position (it used to) and lamp glowing very dimly when driving (so dim I can only see it at night).
I have 5 volts on the harness side of the connector when it is unplugged (other wire presumably ground). I also have five volts on the instrument panel pin that supplies the bulb for the warning light. These wires are different colours.
If I short the harness connector by applying a paper clip between the two terminals then the warning light does not come on. With the connector unplugged the warning light does not come on.
I have been unable to find any reference to this circuit in the wiring diagram. I have even tried wiring diagrams for early legacies to no avail.
So:
Does anyone know if the Z4 Ecu 'uses' this sensor or do cars with this Ecu not have an Egt sensor?
Does anyone have a wiring diagram?

Hi sorry to poach. .but I have the same wagon and have been considering the same upgrades..how much difference is their between the 2 on boost etc..
Cheers

Well worth doing. Now boosts at 0.9 bar thereabouts. Haven't been on rolling road but car feels far more gutsy and doesn't run out of puff like it used to.

Does anyone have any info on this infernal exhaust gas temperature sensor?!

Just an update on this for anyone who changes their wrx wagon to a z4 ECU. The z4 ECU that I put in my car is wired differently for the EGT instrument panel warning light. On the b3 ECU there is no voltage on the wire from the ECU to the dash. When changed to the z4 ECU there is 4.3 volts on the wire. Hence the dimly lit warning light.