Replacing door lock cylinders for 1990 GMC sierra

SOURCE: 1990 GMC Sierra 4x4 1500

the connections near the front axle that activate the motor to engage the system aren't melted? That's a comon problem for that body style. If there good, sounds like it could be that motor itself. To figure out if it's you motor or transfercase, jack up the rear end, have a friend inside shift into 4 wheel drive, or try to, and put it in gear and apply some gas. If the front driveshaft is turning then it's something with the front end. If not, farther back in the system.

SOURCE: removal of power steering pump on 1998 GMC Sierra 1500

you need a power steering pump puller the rest is simple any trouble let me know

SOURCE: My Power window on my 2003 GMC Sierra 1500 Truck

if your main switch panel still works the passenger window and if door locks still work probaly bad window motor

SOURCE: 2004 gmc 1500 sierra heater control stuck on

Defrost is the default position. Is the control a autyomatic temperture control unit? ( you set the temp and select automatic) if it is the system is completely electronic. You push the buttons and the control still says defrost or can you select something else and the control shows it but it just keeps coming out the defrost? If the control changes and the air comes out the defrost anyway and the cheack engine light isn't on, then the problem can be blown fuses or an air door actoater not working. Does the dash emit a clicking sound? if it does with the covers off the bottom of the dash reach around touching the different pieces till you touch the idem that is clicking. this is an acutor motor, or blend door motor. they have gears in them that wear out and break the motors aren't repairable and you just replace the ofending motor. the door that is moves can be stuck. and may have to be freed up with blaster, WD40, or other rust buster till it moves easy. maybe after getting the door to move smoothly you can get the old motor to move the door wiithout having to install a new one.

SOURCE: 1990 GMC Sierra 1500 pickup. Windshield wipers, Cruise Control

May want to look at replacing the wiper circuit board.It is located on the firewall adjacent to the wiper motor and has a some what square black cover with 3 torx screws and wireing harness pluged into the side.We had a truck that every time you washed it the wipers would stay on until it dryed out.You can try removing it and spaying it down with contact cleaner just watch the brease on the two contact tips.Well hope this helps.