152 IAC Code does not Clear

MikeSearay

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I have a 2007 Mercruiser 8.1.HO and I received a 152 IAC code. I replaced both the IAC and the IAC muffler/filter. The boat appears to run fine but the code only clears if I unplug the IAC I tried the new IAC on the other motor and it worked fine. I also put the old IAC on the other motor and got the expected error. I put the good one back on and the code cleared as expected. When I start the boat is says engine power limited and when I go to system on the smartcraft it says 152 IAC. Your input is appreciated.
 
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alldodge

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The IAC's on the 496 have been real problems, only good part is they are the same as Ford uses. The link below is a good read and the big takeaway is, don't run the motor with a bad IAC, it can melt the harness and possibility catch fire.

Note BUP explanation, installation and cleaning

From SB on OSO
Crosses to:
NAPA Echlin #2166509
DELPHI #CV10103

Delphi cheaper at NAPA than the NAPA part. Better quality too. LOL. How typical is that.

Automotive Applications:
Make Model Engine Year(s)
Ford Truck Windstar 3.8 L 232 CID V6 2002 - 2003
Ford Truck Windstar 3.8 L 232 CID V6 2002 - 2003
Lincoln LS 3.0 L 181 CID V6 DOHC 24 Valve 2002 - 2002

http://www.offshoreonly.com/forums/general-q/318109-496-ho-152-iac-output-code.html
 

alldodge

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I try not to do this, but its important to the OP. As soon as the ECM does not see the problem the code will not show up on smartcraft. The code will remain as an old fault until cleared, but is not necessary to clear for the motor to run correctly.
 

MikeSearay

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Thanks for all the info. I have replaced the IAC and replaced the IAC muffler. Boat seems to run fine. Still got the code on the smart craft. I have had other codes before and have been able to repair and not have someone with the scan tool have to reset it. Is this something specific to the IAC issue. I had to run the boat home from where I got the error, however before I did I unplugged the bad IAC and ran back without the IAC plugged in and the boat ran fine. The old one did not appear to be burned and the connector looks good.
 

alldodge

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IMO your asking for trouble. With the IAC plug removed it could keep the IAC full open. If its open then more air is coming in then the computer things is there, this means possible lean condition. Lean condition means your motor is spitting little pieces out the exhaust as you ride along.

Another issue to run with or without IAC is the ECM can fail next. I would be good to put a scanner on it to determine if there are codes showing which smartcraft does not show.
 

MikeSearay

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Hopefully today they are putting it on the scan tool. Will let you know what happens next.
 

MikeSearay

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OK the ECM was bad on the starboard engine. When scanner was plugged it they got nothing. Swapped to the other motor and the problem followed. First issue with the boat that the Brunswick extended warranty actually covered. Still not sure I would recommend the warranty. We'll see.
 

alldodge

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I guess that means they got no codes. Sure been a bugger.
 

MikeSearay

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right when they plugged in they got nothing. Should be installed in a day or two. Is a PCM and an ECM the same thing?
 

alldodge

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right when they plugged in they got nothing. Should be installed in a day or two. Is a PCM and an ECM the same thing?

Their different and the PCM has more functionality then the ECM. In the auto world a PCM = ECM + TCM (engine control module + transmission control module). The Merc does not control the transmission but since Motorola is making the PCM now. Have to go with the industry
Merc 555 ECM PCM.jpg
 

MikeSearay

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ECM was replaced and all codes cleared and boat appears to be running fine. Thanks to all for your help.
 
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