I just bought a 98 Tacoma 4x4 a couple of weeks ago.Whenever you start it the park lights come on.I have also noticed that the trip odometer resets itself every time you kill the truck. The radio looses all of it the station presets when you kill the truck also.The dome light doesn't work unless the key is turned on.I looked in the relay fuse box under the hood and found the fuse to be missing from the dome light.I replaced it and as soon as I did the park lights came on.I am thinking all of these problems are related but have yet to figure anything out.Any help or advice would be greatly appreciated.

A bad ground or some crossed wiring somewhere. Is there a tow hitch or some other thing installed?

There was not a tow hitch on it when I bought it.I did notice there is a plug in for trailer lights by the tailgate.

Hmmm, it previous owner may have did the wiring himself and didn't ground it or mixed up the wiring. No tow hitch, but plug for trailer lights? How are you supposed to tow the trailer I wonder?

I've been wondering that same thing myself.I'm going to look into that wire the next chance I get.I'll let you know what I find.Thanks

I checked the tow light wires and they were fine.I disconnected them anyway and this didn't help.As for the truck being wired with tow lights and no trailer hitch.The previous owner did a lot of work on it.It has a 3 inch lift with 33x12.50 tires on it.They also repainted the frame and changed the hubs out.

Sounds to me like the previous owner got the wireing diagrams mixed up.
More in likely they did work on the Ignition, and tied the radio to it as well.

For the Radio i know...
red: main battery power
Yellow: accessory (on such things as your ignition, so you can only use the radio when the car is on)
Blue: accessory or Power Antenna (same as yellow usually, check manual if you can)

This could hold true for the ignition system as well, although I've not worked on this vehicle before, and don't want to give false information... But it sounds like they tied almost all the power into the ignition switch and did it backwards.
The parking lights for example, perhaps they instead of placing the wire to turn them on to the switch, they put the accessory wire there, and placed the main power to the key.

My guess is that the person either did a replacement of the ignition on the steering wheel or perhaps wired something oddly when the radio was installed. I would suggest taking the radio out and following it's wires and seeing where they go as well as wiring them correctly. With luck this will also show you where perhaps they did incorrect wiring on the ignition as well.

I hope this helps...