When the new shape came out in 2005 the buzzer was fairly loud, as it doubled as the seatbelt warning etc. Alot of people complained about this, especially as for the most part there wasn't a straight forward way to disable it - heck alot of people just stuck a screwdriver through the buzzer to shut it up (it's part of the instrument cluster btw) It's possible they listened to this feedback and made it quieter on later versions. What you want to achieve is fairly straight forward but does require some wiring modifications and as I've never done it before (or read of someone who has) I can't provide you with specific instructions but if you're handy with electrics then the Hilux wiring diagram could provide you with a solution - if it were me I would just cut the lighting wiring for the cluster and connect it to the accessory power, which would have the dash lights on every time the car was running. The lighting wire though might be part of a complete circuit so that would have to be considered and referencing the wiring diagrams should help there. Unfortunately they're no longer online but I think you might be able to find a link on the newhilux.net forums