Always positive impact if you interlink pages which are related. It will have Negative impact when you interlink non related pages.
How would you define "related pages" though? Is it ok if both websites are in the health category, or should they both be related to "weight loss" for example?
You can always relate two health websites, not necessary to go into deep as you said "weight loss", But if you go, it's much better for sure.
Interlinking is not a bad idea if it is to internal pages 2-3 sites internally. If you do that more than 2-3 to main index you could risk a penalty.
HEY! TO Everybody, do not make obvious comments about intterlinking inside a site...that is for sure fine!!! I AM TALKING, AND THAT IS WHY I STARTED THE POST, ABOUT INTERLINKING 3 OR 4 DIFFERENT SITES OF MY OWN, TOPIC RELATED, BUT DIFFERENT SITES!!!!! Thanks for sharing your opinions...
do not ever link between two blogs/sites - i got penalized severely by google and lost my indexing .. sob ..
But not just for linking between two of your sites. That needs more. It can happen if Google thinks that you are creating a linkfarm or linknetwork. But I cannot imagine (and never experienced) that they take one of your sites out of the index for this.
Then it would have been good for you to have said, "I have interlinked my sites", rather than what you actually said: "I have interlinked my pages." We are not children here and don't need to be scolded in all CAPS for your failure to communicate.