Can a bad deferential cause steering issue on 2002 envoy

If possible, pull the horn relay, use jumper wire on switch side of relay, right side in diagram. If the horn sounds, it's not the fuse. Sometimes these diagrams don't post, for some reason? good luck

If the alignment keeps drifting out there is an issue with the suspension. Have the suspension bushes, ball joints and wheel bearings checked. If any of these are worn it can throw out your alignment.
Are you getting any other issues? Things like vague steering, grumbling noises as you accelerate, vibration through the pedals or steering wheel, 'clonks' when hitting potholes? These are all clues to what the issue is.

Have you checked your belt/belts

You need to road test with professional scan tool
& have a shop look up what causes reduced power
fault, on your vehicle

I wouldn't use it,get is diagnosed

Don't need codes present to work on a problem

The answer is most likely already on the internet, if
you make proper use of it with google

that sounds like a rack leak, if so it's the seals inside not the boot

the heat accuator could be bad. It is a motorized part that adjusts your temprature by allowing cold or warm air flow when you adjust the temprature at the knob you are turning

Mine is doing the same thing right now. My husband says it could be related to the odometer, but mine seems to stop when I turn on the heater. I would be curious to hear something about this as well from someone that is mechanically inclined : )

No, its not broken wires, its a pin in the shifter thats out but you need to visit a mechanic unless you know how to open the shifter assembly.

my envoy was doing this too, i went all through my brakes and it still did it, i noticed a bad tie rod end and after i changed it and had an alignment done i dont hear it anymore, so check tie rod ends for play and also check the sway bar end links

Clicking sound- Possible electronic fan clutch failing. This is a typical problem with the 4.2L I6. When you hear the clicking, open the hood and listen if its coming from the fan clutch on front of the engine. this could also cause abnormal engine and transmission cooling. As for the "N" light and 4wd issue, have scanned at the dealer....Hopefully this helps