Long time lurker and Alfa owner here, I'm looking for some assistance with a frustrating Instrument Cluster and Fuel gauge defect.
My GTV is a 10 owner ;-) 1996, P reg Phase 1. My Rolling project car.
Down to the defect:-
When turning the key to the MAR (first position) every thing is normally ok, main instrument cluster C10 lighting dim, ODO legible ie millage and trip displayed.
When selecting AVV (engine running) Alternator power i get 8888 on the odometer, main instrument cluster backlighting full bright (dim switch makes no difference) and fuel gauge full scale deflection (full) triple aux instruments C18 full backlighting. Speedo, Tacho and warning lights are ok.
Now here is the interesting bit sometimes (1 in 20) in will fail in the MAR position, full backlight, fuel gauge full, odo 888. Then the Ceiling light relay I26 clicks and everything returns to normal.
Rectification soo far:-
Initially I was not getting 14v on C10 B2.
I've replaced the 14v pos wire LTB-RED between F15 FUSEBOX G1 connector A7 and Instrument cluster C10 B2 goodcontinuity. getting 14v in ARR.
Cleaned the ignition switch B1contacts and internals.
C10 B1 earth is good continuity, cleaned up Earth point G53g.
C10 B4 is good 12v pos wire to Fuse F16.
Checked B16 Dimmer switch power, earth and switch operation due Backlight on full bright.
Checked C18 aux instruments pin1 14v in ARR, pin2 12v, pin7 earth good continuity.
Checked continuity between C10 B15 and pin3 on aux inst instrument lighting. good continuity.
Cleaned up relay I26 (ceiling relay light) contacts both sides, checked resistance across contacts with 12v power supply all good.
So now i'm thinking C10 instrument cluster has failed, need to try a new one as this controls the timing of the interior light relay by swithing the earth, also sends fuel gauge data to the aux instruments.
Anyone got any other ideas?