When I use my kitchen sink the utility sink in the garage fills up so I think the clog is somewhere were both pipes drain into the main line. I'd like to see a diagram of how they connect

Hi Griggs

Codes are similar from state to state, but there is no way we can guess at how the pipes in your home come together.

In this case, you will be best to snake the drain from the sink closest to the main drain. Hopefully, you will find a cleanout to snake down or you could always snake the drain via the vent if the roof is flat enough. If you have a PVC or ABS plastic drain you could also cut in a cleanout or a clamp and snake the drain through that!

Back to you...

Mark