2005 Indmar 8.1L TAC Fault
 

Owners concern is it runs rough, of course it runs fine for me, but it makes sense when I pull codes, it has 6 different TAC codes. All code 81, descriptors are: TPS #2 range fault, TPS #1 range fault, Limited authority, Actuation fault, Not tracking. I did the usual visual inspection, harness shake down, inspect connector pins, cycled the throttle both running and off, monitored scan data (minimal). Cleared the codes and none have reset.

I have never had much luck with intermittent faulty throttle bodies, any testing suggestions? The manufacturer trouble shooting info isn't very helpful, basically they tell you to do a visual, check the connector fit, and if that checks out
replace the TAC module, and if that doesn't fix it replace the throttle body. If this was a truck I would be leaning heavily toward the throttle body, but I hate to guess.

Thanks for reading.

I'm more familiar with the Mercury 8.1, but can you adjust the TPS voltage on the Indmar?

It's the same engine, a GM 8.1L Vortec. The TP on these is not adjustable, it's an electronic throttle body, there are 2 sensor built in that are not serviced separately.

Ahh I see. I had to set the voltage on mine but it's a 496HO with a Whipple supercharger so it's an aftermarket TPS/throttle body that comes with the kit.