Convertible top ground location

[rekstein1]

1988 Porsche 911 carerra convertible. top was working great then nothing. Sent the cpu control unit to Ecu in Florida as it was under warenty. It failed there and they replaced the unit.
The car is being handle by a mechanic who deals with high end cars and he is struggling.
the top will operate if jumped at one of the 4 plugs. in that it goes up and down. the limit switches will work if engage. motors will lock and unlock. Check the contacts at the
convertible top switch. cleaned and checked wiring to the cpu. all good

I gave him the control top test pattern here on the forum to follow. still a problem.
I gave it to him because i could not figure it out either. The first step in testing was to check from plug 31 to 30 to make sure the ground was good. Personally i went through the test directions and got everything to work just as he did.
I was never able to confirm the gound from 30 to 31.

Does anyone know where the ground wire is on #31 pin goes to?Some of the schematics that i am looking at say G202(left side member)

where the hell is that?

anyone have any ideas as to why the convertible top will work when jumped and not through the cpu when hooked up. SEnding the unit back to ECU repair to confirm the unit is not bad

And no I am not going to manuell opening and closing
It worked well for 8 years ,the problem is somewhere

does anyone thing its the main grounding strap?

thanks for your input