2006 Suzuki Boulevard C90T four ways only one in the front and one in the back work any idea what's going on

Behind the right side cover.

https://www.motorcycleforums.net/threads/c90t-b-o-s-s-flasher-relay.53698/#:~:text=It%20is%20behind%20the%20charcoal%20canister%20under%20the%20right%20side%20cover.

Pictures
https://www.google.com/search?q=2013+Suzuki+Boulevard+C90T+flasher+relay+location

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The oil filter is located at the very front of the engine. It is below the battery, thus making it rather difficult to see. It is mounted in a horizontal position under the battery bracket.

try removing positive cable from batt. for 5min.
replace turn ign. switch on about 5sec. dont crank it.
cut it off.now crank it.
see if that correct he problem

http://www.bikebandit.com/2006-suzuki-boulevard-c90t-vl1500t-front-damper/o/m147608sch518555

You'll need to remove bolt (part #11), and probably come up with something to hold (part #14) from spinning while you do.

Look at the heads of the cylinders on either side of the bike. You will notice that a head on either side has smaller screws then the other. I believe they are 8mm screws. Under those heads (with the smaller screws) are located your spark plugs. When pulling them out make sure you spray comressed air around the plug to ensure no dirt gets in once you pull the plugs all the way out.
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Have you had the front wheel off lately?
The speedo sensor may have been broken when the front tire was put back on (a common thing, and easily broken).
The wiring harness under the speedo may have vibrated loose also.