Where are the ground wires?
 

I have a '99 S70 non turbo, 220,000 miles. I am extremely happy with this car and I haven't had many problems with it until now. Recently I have been dealing with a constant check engine light that is throwing multiple codes at different times. I'll check the codes, right now its a Small Evap Leak and Knock Sensor, and then reset the light. Within a couple days the light will come back on with yet another code for something different. It's driving me crazy!

I was told by my uncle who is a mechanic, that a common problem for older cars is the ground wires become corroded and don't ground properly causing things to seem like they're bad. So I am wondering where all these ground wires can be found so I can clean them up and hope these random codes go away.

I know of the ones that come off the negative battery and ground to the frame behind the headlight and the block itself. (I wire brushed them and actually got my oxygen sensor and one other code to go away) Where are the other grounds?

Thanks in advance!

That is most of the main ones. Did you clean the tranny one?

Yeah, I got that one too. I guess that's about all of them.

There is also one on the front of the motor to the left of the oil pressure switch.

Mine is turbo model 99 s70 but it has one by the air box on the fender. I am also wondering if the green fabric cables attached to the upper front and upper rear of the engine on the firewall side are ground. If not, I am curious what they are.