496 HO 152 IAC Output Code
 

Developed a soft alarm 2 beep last weekend. Happens when you turn the key on and when running every few mins. Went over 4500rpms and it went into a hard constant alarm until I came off plane. All gauges etc... Good. Got my Rinda scanner today and it showed an active 152 iac output code.

Fault history showed 9 guardian, 19 overspeed, 152 iac output, 77 cam sensor, 132 crank sensor.

I visually looked over the iac. No burnt connector or the like on the iac itself.

Cleared all faults and powered down. Rechecked and 152 iac came back on active faults.

I plan on replacing the iac tomorrow.

This is my first time troubleshooting with the scanner and just wanted to get a second opinion on what info it's showing.

Thanks

Change your IAC and the gasket, make sure the surface is clean - next change the IAC muffler and clean that cavity it sits in. Next take off your flame arrestor and clean it from the inside out.

When installing new IAC do not tight one bolt down and then next. Tighten one a little then next side a little until you get you get proper torque.

Also you failed to mention what motor you have and the year model. 99% of the time it is impossible to give out sound advice not knowing what you have plus is the engine stock or not. Anyways just saying but the IAC's are a problem child for the past 20 years in marine apps - more so from 2001 to 2010 year models..

Thanks for the reply. 06 496HO Bone stock 414 hrs. I plan on doing the IAC Output test running on the hose this afternoon. Local marina has the iac in stock. Thanks for the tips.

In the future, buy an IAC from www.rockauto.com

MUCH cheaper than Mercury.

You can likely find it at a local auto parts store as well.

Gotcha. I'll check the auto stores. Trying to get a last warm weather weekend.

And do not keep running your boat with a bad IAC. A couple of things can happen - one is melt or even catch fire to harnesses that the IAC plugs into. Also over time a bad IAC can cause ECM / PCM failure and this can be so true with the 496 Mercruiser.

Also if you have a good Ford connection or work for a Ford house - you can buy it from them. Its a Ford IAC anyways. Funny how cheap it is compared to even dealer pricing thru Merc or Volvo.

You can also get it here: http://shop.advanceautoparts.com/p/b...zoneAssigned=1
Buy online and enter coupon code TRT30 and pick it up for a little over $30.00 before taxes within 30 minutes...
http://www.retailmenot.com/view/adva....com?c=4536452

BWD Idle Speed Control Motor
Part No. 50558

Thanks everyone for the help. Picked up a new IAC from a Napa close to my home and installed. Also pulled and cleaned my IAC muffler. Gonna be replacing the muffler for next year though. TB and flame arrestor were both cleaned less than 25 hrs ago. Noticed the original Iac internal plunger was not in the same position as the new iac.

Scanned ECM and no active IAC fault. No 2 beeps every couple mins like before. Ran the engine on the hose for 20 ish mins to operating temp playing with the scanner and no problems. Very cool being able to monitor in real time engine functions.

One thing I find strange is I tried the IAC output test, and there was no change in idle rpm when changing the Iac in 10% increments? Seems the problem is fixed but any ideas on this.

Totally agree with this advice. I had the double beep followed by a melted harness. My story and the fix (with pictures) here.

http://www.austinboatforums.com/cgi-...num=1401221891

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

Hey thanks posting the IAC problem child and what can happen. Even some techs do not believe me when I tell them to the change IAC & gasket first then test drive the boat because you never know when a bad IAC will knock the ECM / PCM and or catch something on fire. Also bad ignition coils especially the first years for the 496 can knock out the PCM in a split second. Seen it, done it and fixed it as well. I think I even have a t-shirt about it as well.

Have to ask as to your on the big island boating - how did you come up with posting on the Austin TX forums ? just asking. That's a long boat trip away. LOL

Ha ha! It is a long boat ride! Good question. I moved to Hawaii last year from Central Texas. I'll be here at least a few years before going back. Still post on the Austin Forums because the crew over there is a great bunch of guys and it helps keep me connected with Texas.