The dimmer switch is on the dashboard just to the right hand side of the steering wheel
For the coupe: 89 litres; 20 Imperial Gallons; 24 US gallons
The B.O.O. switch or Brake On/Off switch is located at the top of the brake pedal assemble.
This is not extremely hard but you do need direction. Get a manual on your car from the parts store or DiSCOUNTAUTOREPAIRMANUALS.COM
Fuel Fault code 89 translates to "Purge valve circuit. Looks at voltage across purge valve winding to detect open or short circuit."
I'm not aware of anywhere you can buy them new or anyone who has a free electronic copy. I acquired a manual for my '89 XJ-S for £10 on e-bay. There's usually a couple of manuals for sale.
Be sure headlight switch is ok. On my 89 there is ground wire on body in front of battery and dirty connection will activate circuit breaker in headlight switch. Could be dimmer switch on column under dash which may be hard to remove without lowering column. I unplugged old dimmer switch, plugged in new switch, set it to dim, and wired it to column so now only have dim lights( but can drive at night) as old switch still connected to activator rod which goes up to turn signal/dimmer handle.
Check repair book but my 89 has circuit breaker in headlight switch. There is ground wire on body in front of battery. Bad ground will cause breaker to activate so unbolt ground and clean connection. Could have bad dimmer switch which is on column under dash and may be hard to remove without lowering column. I unplugged old switch, plugged in new dimmer switch, set it to dim, and wired new switch to column so now only have dim lights as old switch is connected to activator rod which goes to turn signal/dimmer handle.
There isn't a remote trunk release on mine (i.e. from inside the cabin). The trunk unlocks on the central locking and/or can be unlocked with the key The release lever for the trunk lid is beneath the lock between the license plate lights. It's a chromed lever
Only a suggestion I'm afraid. I thought that the dash lights weren't working on my '89 XJ-S until I tried the dimmer knob in every possible position. It produced a very dull glimmer for about 10% of its total range of movement somewhere between 60 and 70 % of the way round and nothing anywhere else Before you write off your dash lights try all possible positions for the knob
On my 89 Corsica switch on column under dash and may be difficult to replace without lowering column. I unplugged old switch, plugged in new switch, set it to dim and wired it to column so now only have dim lights so this might work for you as I believe Berretta and Corsica the same for this.
Standing in front of the car facing the car, you will find it on the right hand side. It has a black cap on it that needs a twist to open and has some filling instructions written on it. Look carefully, it is situated between the aircleaner filter and the front engine pulley. Difficult to fill without spilling.
On my 89 there is a ground wire on the body in front of battery. Bad connection will cause problem with headlights. Could be hi/lo dimmer switch under dash. Hard to replace without removing steering column but I unplugged switch, plugged in new switch, set new switch on dim lights, and wired new switch to steering column so I have lights but only dim lights