I have a 2012 Tahoe Q5i with Mercruiser 4.3TKS Alpha One (serial # 1A637788). For some reason i can't locate the Throttle Position Sensor. Any pics or help would be greatly appreciated. I get a loud alarm when going to forward and reverse but not in neutral. I called the dealer and he said he was pretty sure it was the tps

Thanks for the serial number, and you are correct your motor has a TKS carb and therefore does not have a TPS. The dealer either doesn't care, didn't actually listen to what you were saying, or a DA.

Do you have digital controls or cable?

Here is what they look like

Been thinking more about it and it could be your oil pressure switch. This switch sounds the alarm when oil pressure is low but also powers the fuel pump. It could be when you go into gear the oil pressure drops just enough to turn on the alarm. It would turn off the fuel pump but you wouldn't know it right away with a carb.

My guess is your oil pressure is fine and what you see on the gauge has no effect on the switch. Easy way to prove it, is when the alarm sounds, pull the plug off the switch to see if alarm stops.

i will check. Thank you for the pics and reply.

I am a fairly new boat owner and learning every day. If the oil pressure is fine and it is the switch, what would be my next step?

If its the switch the part number is 87-8M0070108 and is item 10 in link below.

Be sure to check your oil pressure is not low (not under 10 psi at idle).
When you shift in gear, if you give it a little throttle does it stop?

Genuine Mercury & Mercruiser parts. Electrical Components

there is NO TPS on Merc carb engines.

TKS is Merc way for TURN KEY START not having a choke in their carb design 2 bbl Merc carb

NO alarm for any fuel side on MERC carb apps period.

the dealer is clueless if he told you this and IF you REALLY have a carb TKS 4.3 engine