Just bought a 2002 S60 with 112K miles. The instrument cluster would work intermittently. All gauges, all lights, and displays, would work then suddenly shut down; go completely dark and gauges would pin out, then everything would come back on. On for 10 minutes +or-, off for 20 minutes+or-, an obvious short somewhere. I did notice at times I still had Temp and Fuel gauges, but most often everything was dark. Most posts pointed to possible cracked solder on the instrument cluster circuit board.
I removed and dissassembled the cluster. I studied both sides of the curcuit board, especially around the main wiring harness connecting pins, with a magnifying glass looking for cracked, or bad, solder joints. I found that someone had already made some solder repairs at the main pins. The job was sloppy with some solder splatters on the board. Some of the pins had a little corrosion. I cleaned flats areas with a cuetip and soldered pins with a small plackers dental brush, both dipped in isopropyl alcohol. I also checked the first foot of wiring harness in the car, that attaches to the cluster, for damaged wires. All wires appeared to be good. I reassembled and tested the cluster back in the vehicle. This did not fix the problem.
What I noticed when I reassembled was that if I pressed in on the exposed metal plate on the back left hand side of the cluster, all the lights and gauges would work. See link for bigger pic of exposed plate: http://i.imgur.com/nFS6B.jpg?1
This pic also shows my alteration to the back panel. You can see my "Fix" above the exposed metal plate. See next pic http://i.imgur.com/4Brcm.jpg
The fix was made by running a bolt through the metal bridge plate and circuit board and using a nut to apply tension to the metal plate. This tensioning by nut and bolt acheives the same effect as if you were pressing in on the exposed plate.The next pics show how this was done. Note in the pic above that I drilled a hole to allow the nut to be exposed which also allows the back panel to properly seat. This also allows me to adjust the tension on the metal plate without removing the back cover. Proper tension seems to be key. Don't over tension. You can break the board. Make sure you remove the cover from the circuit board before attempting to drill a hole. If you hit the circuit board with a drill bit, you could very well ruin the board.
Okay, so how did I know to put a bolt and nut here? Because, there is an existing hole in this metal plate and a correspondig hole in the circuit board. I have no idea what this metal plate accuately does. I have a therory that the rapid expansion and contracting from the super heating and cooling that occurs within this metal bridge could be what is cracking the soldered connections. The metal plate bridges a large area of the board. Tensioning the plate and circuit board may be closing a crack I can't see. I inserted the bolt through the existing holes in the circuit board and the metal plate.The head of the bolt I installed sits against the circuit board. I only had a long bolt. I cut it to fit. You can use a shorter bolt http://i.imgur.com/vftkm.jpg
I also drilled a hole in the front panel cover (white one only). See pic below. Again, remove the front cover from the circuit board. This requires you remove the gauges. Don't bend the hands on the gauges, and don't bend the spring pins when reinstalling the gauges. The gauges require the spring pins to be inserted properly in order for the gauges to work http://i.imgur.com/TlWCv.jpg
Above is a pic of the hole in the front cover. Both holes in the front and back covers allow me to retension the bolt without disassembling the entire cluster. After you test the unit in the car, It is a good idea to dab a little silicone on the nut side of the bolt to keep the nut from vibrating loose.
Pic below shows the head of the bolt in circuit board. Note the blue tape to the right. At the same time I did the bolt I noted what looked like a cracked solder joint where a lead attaches to the bottom of a 1/4 inch black resister. I resoldered this connection. I used a 25 watt pencil wand, with 40/60 small diameter rosin core solder with flux in the solder.The blue tape is to protect the board from drips and splatter. I did not check this repair separately from the bolt work, So I can't say if resoldering the connection had any effect. (I have since re-tensioned the nut and bolt when the cluster blinked out once. The nut was loose, so I added silicone to the nut to keep it from moving again. This solder repair did not have any effect.) http://i.imgur.com/vftkm.jpg
Okay, this worked for me and saved a $450 replacement. How long will it last? Don't know but its working now!
Look on youtube for instructions on how to take out the cluster
and also how to solder.
Update: 12-14-12 Still working.
Update: 3-30-13 The cluster's operating condition started deteriorating again beginning in March. I replaced the unit around mid-March with a remanufactured unit from Xemodex. The fix had the instrument cluster working perfectly, except for the clock, for about three months, and it did buy me some time.