Garry, I have the XJS instrument panel schematics for the 1989, 1992, 1995-1996 for the V12 and the 4.0 where applicable… My wife’s 1992 has a facelift instrument cluster, and two '94 spares. I can tell you there are some very minor differences - an example would be the Amber ABS light and Red Brake light when the Teves IV came to the XJS. No change to the panel, but how the wires from the panel connected to the T4 ABS - very simple, So, I can say, with respect to the subjects we have discussed - no changes.
FYI, my wife’s first XJS was an '89 coupe - that was the car I did the first crossover from an '89 Panel to the '94 facelift panel - it worked perfectly, and was the basis for my crossover charts.
Let me say this, You can completely remove the instrument cluster from the car, and the turn signal system will work just fine, but no panel indication lights. You have told us that your turn signals work fine - except for the indicator lights. To me, that means your connections to the indicator lights are not correct. You are not the first to be confused by the GW to GR an/or the GR to GW connection reversals. I realize most of the wire colors match, but the turn signals are one of the exceptions to that. Fundamentally, the plug, plug pin position, and function are primary over the wire colors - so let me give it another shot with regard to the turn signal indicator lights only:
LHTS - The wire (GW) from the '89 big plug A6, must be connected to Facelift big plug A3 wire (GR).
RHTS - The wire (GR) from the '89 small plug B6, must be connected to Facelift small plug B10 wire (GW).
'89 big plug “A” has 18 connection positions Facelift big plug “A” has 18 connection positions
'89 small plug “B” has 12 connection positions Facelift small plug “B” has 14 connection positions
Connected as above, the indicator lights should work correctly - other wise suspect burnt out bulbs or instrument panel damaged wiring.