Well I'm still researching the EST Code 42 and the head liner issue....... I was wondering if anyone would have any insight into a few more things.........

1)My temperature gauge is not working.....no way the car stays that dead cold..doesn't budge...Maybe a fuse or sensor?????

2) Trunk release button in glove compartment only works occasionally.. connection?

3) Interior lights do not come on when driver door is opened..pushed on switch in between door and frame..pushes in and out fine. LIghts do come on when passenger is opened...

Do I just have an electrical disaster in this car or what ? hahhahh These little things are buggin the **** outta me.....Appreciate any help....

man, sounds just like mine. my temp gauge would read cold all the time too, till i got a new thermostat. my trunk release button quit working and never started again, and the light wouldnt come on for me either, just the courtesy dome for pushying the button. go figure bud.

Only way to know is with a scanner and there are a bunch of OTC 2000s (I have 2, no, they are not are for sale) on e-bay right now. Just make sure you get a GM cartridge for your year (though I have used an 88 GM cartridge on our 90) and the GM cable. It helps to have the GM book or cards to know which function is which.
http://search.ebay.com/otc-2000

I changed my door pins and that solved the problem for me on the Bonneville. The pin is probably corroded inside causing the lights to not come on. It was pretty cheap too. I went ahead and changed both.