Idle Air Control Motors
 

Anybody seing failurs of the IAC,s at about 150 hours. When they fail they trip the guardian system and default to limp in
mode. Specifically on 2004 and later 496 and 525??

I see them weekly at my shop

Me too, it's very common. It's heat that kills them. I think Merc needs to design and retrofit them with a heatsink of some type for better cooling.

Dave

GOOD ADVICE:ernaehrung004:

When they go bad they usually do put the engine in the guardian mode. Luckily it's an easy fix.

Belt dust usually kills them also. We have seen a lot in our shop also. They just changed the design for the filter in the small blocks this year. We will see howit goes.

more so is carrosion. and not allways do they put engine into guardian mode. this is due in part to having a functional electronic side but a frozen or malfunctioning mechanical side on the i.a.c . i had 7 last week, 4 of which did not show up as fault codes. an easy way to tell is to listen for the missing hiss during start up or after shifting.