I need the schematic for 1994 gmc sierra 5.7 2 wheel drive knock senser wiring diagram to the brain.theres no plug for it on the new motor i put in.

Question edited for clarity.

This is a job for an auto-electrician unless you can read wiring diagrams.

Yukon
https://www.google.com/search?q=1994+GMC+Yukon+power+mirror+wiring+diagram

Sierra
https://www.google.com/search?q=2000+gmc+sierra+power+mirror+wiring+diagram

..

Hi Steve,
Try search terms "GMC Sierra 1500 wiring diagram". This should yield a good few hits like: Schematic me Free Electronic Schematic Diagram and. http://fuel-saver.org/

That truck did not use a vacuum actuator, it used an electric motor motor. If your transfer case is engaging and you can see the front drive line spinning, then you either have a bad actuator, switch, or the wiring is bad. I would recommend unplugging your actuator and checking for power at the wire while someone puts the truck in four wheel drive. If there is power going to it, then replace your actuator. if not, follow your wiring back and check all components. They also sell an aftermarket cable actuator for those trucks which are much more reliable.

Looks like the wire from the sensor to the module is dark blue.
You can find the engine diagram on autozone's website under repair help.

Just ahead of the starter the knock senser just screws into the side of the block. The problem is it screws into the engine coolant and the coolantr will come out then you remove the old senser. even if you frain the raditor coolant will still be in the engine ( quite alot) and you'll need to catchir in some way. You can get about 2 gallons. The messly way to do it is to ( with the engine cold) loosen the senser till you can turn it by hand. With the new senser in th=your other hand remove the senser and quickly screw the new senser in. You'll almost certainly get coolant on you so be eady, covering your eyes and arms ( glasses and a raincoat) you do it quickly eniugh very little mess will be made. The plug just squeezes and pulls off. Knock sensers seldom fail but the connection and the wires do. Someone replaceing the startercan hit the senser and break it. Don't drop the senser as the fall can break it too.

Generally a Pinging noise isn't due to a knock sensor. It sounds like you may have Detonation issues.

I'd really check your spark plugs to make sure they are not fouled as well as running some higher octane gas to see if it helps.

basically, your getting combustion earlier then you're supposed to. This could be to various reasons.

Check in this order, Spark, Timing.

Check to make sure the spark plugs are all sparking and clean / properly gaped. Pull one coil/wire at a time off the plug to see if the pinging stop (pull a wire, start the car. Turn off car, re-attach wire, move onto next plug.) If it stops on a specific cylinder that means you're having detonation issues on that cylinder. If it never stops, then it sounds as though it could be timing related or have a valve train issue.

We'll start here and move on. Let me know what comes of this!

It is the buttons. It is about a $50 part new on ebay. Easy to replace. Just pull gently on the dash bezel. I believe there are two screws/bolts. Pull it out and disconnect the wire harness. Then just plug it in and put it back together.

you may have a bad frt diff seliniod, try unpluging seleniod and putting into 4wd, if fuse doesnt blow then you know its the seleniod.also take a look at the wiring at the transfer case for any chafed wires,some of these trucks use vaccum also to operate 4wd check the vacuum switches for shorts,ive enclosed a wiring diagram to help you ,hope this helps ,good luck.

http://www.motoralldata.com/alldata/MOTOR~V154694308~C19848~R0~OD~N/0/41746052/42418500/42418505/42419860/34853741/100411974/34853743/58948514/34849806/144571248

The best way to get a good diagram would be to get a haynes book from an autoparts store. They often lend them out for a small deposit. Depending on the motor i could give more information.