As for the trunk popper:
There could be a problem with the switch itself, the wiring from the fuse box to the switch, from the switch to the trunk, or the solenoid that actuates the trunk lock.
If you're handy with a meter, you could probe the circuit. First remove the fuse for that circuit and put the two test leads in place of the fuse. Set your meter to volts and press the trunk pop button.
By pressing the button, you are completing a circuit and the meter should read "12" volts. If not, then there's a break in the circuit somewhere. You'll then remove the meter lead from the ground side of the circuit and place that to ground. If it reads 12 volts, then the "battery" side of the circuit is good, if not, then you know that side of the circuit has a break in the wire and you'll have to find it.
Also, if that side of the circuit is good, then you'll have to test the ground side of the circuit. Set your meter to "Ohms" and place one test lead into the ground side of the fuse. Place the other lead to ground then press the trunk popper. If you get continuity, then that side of the circuit is good also. That would mean the solenoid that actuates the trunk lock is bad. If it does not read continuity, then you'll have to trace the circuit until you find the break.
If it's only your trunk button that's bad, a key fob will still work. If it's the circuit, then it won't. As for your key not opening the trunk, it sounds as if someone changed that lock, and you'll have to get a key made.
As for your heater display, these frequently go on the blink. If the rest of the control module works, then you'll know it's only the display.
If you can remove the control unit and take apart the display, you could buy a used one from the junk yard that works and swap it out. If you can't remove it, then you'll have to have it replaced.
Saturday, January 16th, 2010 AT 7:21 PM