1989 GMC Sierra - Answered Questions & Fixed issues

changing the transmission is not an option as it is working good the problem will be an actuator or servo/solenoid take it to an auto transmission specialist professional and have it properly diagnosed

Are you sure that it is getting gas, you can take a gas can and pour a small amount down the throttle body (just a teaspoon or less) and see if it starts to run while turning it over. Becareful with the air cleaner off you could get a back fire (fire!) so only use a small amount of gas and have a fire extinguisher near in case you get a flame up. Could be the distributor if it is loose (as it became in my 1988) the distributor hold down fork became bent from over tightening the bolt and it would not stay in position. You will have to slowly turn it if it moved (or use a timing light) to adjust it till it will run there is a connector near the brake booster that needs to be disconnected to properly set the timing.

Is the EFI spraying gas or dripping gas by anychance. I blowed a o-ring at the base of the injector on mine and did that to me.

Have you replaced the fuel filter? It;s under the drivers side in the frame rail.

The stop lights won't go out until the pedal is depressed, as there is a switch which is activated by the pedal. A hard brake pedal is probably caused by a defective servo. The hissing noise is probably an air leak in the servo. Switch the engine on, open the bonnet (the hood..) and see if you can locate the hissing - that'll probably be in the brake servo area. If you don't know what a brake servo looks like here is a generic image:

it should.......but a transmission shop will need to verfiy it. Get the trans pan off and check the condition, (excessive metal in th epan) and replace the filter while its out. Have a trans shop check it, you dont want to put in a bad trans.

if it has a 4.3 liter motor a 86 to a 97 if it has a 350 motor a 81 to a 96 will work hope this helps

most likely you'll see the bulb socket protruding in the back of the headlight, gently grab it and turn slightly to left or right, there three tabs on the base that line up w/ 3 holes and the light assembly will slip out....don't be afraid to discuss this with the guys or gals at the autoparts house- they love to give out advice.....hope i've helped in some manner...pappy

Solenoids inside the transmission or the control module.

Maybe to much fuel. Does your coolant gauge work or register? Could be the ECT sensor. Could be fouled plugs also. Do you have smoke coming out the back? is it black smoke?

electronic spark control module is bad

On the frame its more stable door is too weak and the spring move when you lift

Bad temp sensor ? Just a shot in the dark without being there to check it myself but a common problem.

Check for a blown fuse?

dull head lights cab be from several things 1-bad reflectors behind the bulbs --any yellowing, rusting or dull reflector surfaces -- replace head light assemblies 2 badly aligned head lights-- beams shining off into space instead of on the road. --- have an alignment done on the lights 3 wet roads do not reflect head lights properly so it appears that the lights are not working well--- not much to do. the light reflects forward of the wet surface and not back to the driver 4 only one head light or no main beams and running on low beams only--- check light operation and check light control module for operation

hook to scanner look at the coolant temp sensor data if it is reading colder than it is outside like example if it's reading -36 degrees its causing the computer to dump in way to much fuel .. if this is the case replace sensor and it should be fine

Computer is behine glove box ,,, if thats what your looking,,, need to be alttle more specific

A GMC dealership will pull that up for you. Most will print it off for you as well.

If all you did was lose the key, copy down your vehicle identification number (VIN) which is on the dash, and take it and your registration and personal identification to the dealer to prove you are the owner. They can look up what you need and make you a key. :)

look for vacume hoses off or cracked