If you have had it repaired before then it maybe corrosion of the chip soldering due to not having been cleaned of the solder flux. If it is just damp in the chip then you can dry it out with a heater or oven bake it then lacqure it. We discussed it here >>
http://www.matrasport.dk/forum/index.php/topic,2386.0.html. I have one here I have just done where the das was not displayed, it was the body controler in the left floor fuse box. Take the cover off & fire a heater at it. If you are any good with a soldering iron then you could reflow the solder of the connectors of the chip.
Brian