How to get guages working again?

Ok my speedo , gas and battery work. They run independently.
The tach, oil and temp dont. I think it might be the afternarket wiring harness, the kid put one in and might have screwed up?
He also put in a new distibutor, so maybe thats why the tach is screwed?
Any personal expierences with wiring harness' and distributors?

bump