Electrical

My 2005 Chevy Avalanche 2500 8.1 has had
nothing but electrical problem since I got it. Feb
14,2017.  When I first got it it had an alarm. Or I
guess it had the alarm the whole time it was just
working when I first got it. Then one day I couldn't
see behind me so I open the door to look and back
up and ever since the truck thinks the door is open.
The lights come on and off- the doors lock and
unlock- it dings and I've gone through that for
almost 18 months. And it seems to act up more in
the rain.  Now my heated seats are turning
themselves up and down. We replaced the sensor
in the door--$300 thank God my husband fixes
them himself. Recently he found an override for a
car starter so now I'm thinking its sending bad
signals. And last but not least now my cruise
control is out. I can see the light coming on but it
won't engage. By the time I'm done paying for this I
will have played close to double with the vehicle is
worth. And I still owe money on it. SO trading it in
or selling it is not an option. I've definitely thought
about it. I'm so angry with myself because there
was a Nissan Titan for $3,000 cheaper,less
mileage and newer.  we didn't even go look at it
because of all the great reviews we saw when we
looked up the Chevy Avalanche. people were like
oh I've had five of them that's all I ever by. One guy
said he has to keep looking behind him to see if his
boat is there when he's Towing it cuz it's so
powerful. And all I've had is one problem after
another. Technically it's still running as far as
dependability the motor and transmission are
great. But the door lock thing is really annoying.
And dangerous at night when the lights are
flashing on and off. But now that my cruise control
is gone that is the last straw. That is what saves
me from getting tickets. Please can anyone help??