Top 20 1989 GMC Sierra Questions & Answers


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

1989 GMC Sierra | 28 views | 0 helpful votes


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.

1989 GMC Sierra | 44 views | 0 helpful votes


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.

1989 GMC Sierra | 58 views | 0 helpful votes


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:



26071617-5gult0ot5kkhyupfos0rfps2-1-0.jpeg

1989 GMC Sierra | 116 views | 1 helpful votes


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?

1989 GMC Sierra | 109 views | 0 helpful votes


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

1989 GMC Sierra | 82 views | 0 helpful votes


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

1989 GMC Sierra | 125 views | 3 helpful votes


Did you open the hood? It could be a popped serpentine belt or a broken timing chain or timing belt.

1989 GMC Sierra | 144 views | 0 helpful votes


A bad/loose connection at the plug. In the cluster or the speed sensor.

1989 GMC Sierra | 86 views | 0 helpful votes


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

1989 GMC Sierra | 265 views | 0 helpful votes


Hello Rick ,is it possible there was work done on it? ,jack up front end and see if the same thing happens,also , have one person turn wheel slowly while you watch it go left and right, is there any damage to "U" joints in front end

1989 GMC Sierra | 44 views | 0 helpful votes


Check for a blown fuse?

1989 GMC Sierra | 32 views | 0 helpful votes


Your mass airflow sensor should be right behind the air filter box. It should be in the hose between the airbox and the intake manifold. When you find it, just take the clamps loose and disconnect the wire connector to the sensor. Take the sensor out and clean it with a can of electrical cleaner or brake cleaner. Put it all back in and see what it does. It's also possible that it is a bad sensor. Clean it first and see what that does.

1989 GMC Sierra | 88 views | 0 helpful votes

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