Pictures of ground locations
 

The 87 wagon I have has lots of electrical gremlins. Largely due to corroded grounds. The hardest part was finding the ground locations. The members of this have been helpful, but for a novice like myself pictures are nice.
https://cimg3.ibsrv.net/gimg/volvofo...f836318d7a.jpg
Did I mention that this snake feasted for years in this car while parked and got to be 3 feet long. Rodent problem.
https://cimg3.ibsrv.net/gimg/volvofo...f224b40033.jpg
Trans selector light. There is a ground not pictured on the other side.
https://cimg0.ibsrv.net/gimg/volvofo...a7612161d1.jpg
Ground on trans tunnel driver side. You may be able to access this without removing the seat and carpet.
https://cimg6.ibsrv.net/gimg/volvofo...d5ac5148d5.jpg
Rust never sleeps
https://cimg6.ibsrv.net/gimg/volvofo...a606552eb2.jpg
Ground above air control
https://cimg3.ibsrv.net/gimg/volvofo...02dd9f2481.jpg
The black ganged ground on the steering column got the black ground in the large circular female connector working, and then the dash instrument illumination lights came together.

note they tend to use different grounding points for 'signal' grounds vs 'power' grounds. this reduces noise in the more sensitive signal circuits. on the engine itself, there's two grounds, one for power hungry stuff like the injectors, other one for sensitive stuff like the sensors. diutto, the left and right dashboard grounds are segregated the same way, I *think* its power on the left, signal on the right, but I might ahve that backwards :D