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Replacing Idle Air Control? - How to place into service mode for recalibration - 2003 Malibu Response


Bass Lake Skier

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I have a 2003 Malibu Response with the indmar 340 motor- I had the buzzer going off and after reading a ton of great posts have narrowed down to the IAC plunger. You start it up and the second the boat starts to pulse up and down in RPMs the alarm goes off. I purchased a new IAC. I believe its nothing more that a small stepper motor. Through my reading of posts it sounds like until you put your boat in service mode it will not recalibrate and work properly.

I have not done the "Service Mode" trick yet. I've read a lot of posts that mention it but now where does anyone step through in detail on how to put the boat in service mode. Also. How do you take back out of service mode.  Video would be awesome but a verbal description would help as well

Any help would be great. My son has not been in the water for nearly a month as I try to chase this problem. 

Thanks! 

Edited by Bass Lake Skier
Changed ECM to ICM in case someone else reads this they aren't confused. I used ECM where I should not have.
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I have used Rinda Diacom to reset the IAC on a MEFI4, but I am not sure if putting the engine in service mode will reset the IAC or not.  Of course, service mode can be turned on or off using Diacom to set the base timing, but I think shorting the A and B pins on the diagnostic connector will also put it in service mode.

Even though the IAC does control the engine idle speed the IAC does not report back to the ECM.  The ECM just commands the IAC to open or close to a number of "counts", but the ECM does not really know the actual position of the IAC, so I really doubt that any problem with it would cause the fault alarm buzzer to sound.

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I never did put mine into service mode when I installed mine.  Have you already installed the new IAC?  If not, it's very easy:

 

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6 hours ago, Bass Lake Skier said:

narrowed down to the IAC sensor.

Idle Air Controller is an actuator, not a sensor.  If you have trouble with it, it is most likely just dirty, not broken.  My understanding is that the IAC pintle recalibrates at every key on so that the ECM knows where it is (by counting steps from a baseline, as @csleaver mentioned above.  If you have rough idle, grab a can of carb cleaner and clean the throttle body.  It is a bit hard to do on your engine, but you can lean your head in and see where the spray is going.  Get the edge of the butterfly and its seat by opening the throttle.  Make sure you get the side passages as well.

Your engine runs completely open loop.  I'm surprised that @formulaben didn't post his list of the four things that can cause an alarm, but perhaps he will.

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BEEP CODES — the 4 maintenance items that can trigger the beeper are:

  •  High engine water temperature (NOT dash sensor, and >203*)
  •  Low oil pressure (NOT dash sensor, and <6 PSI)
  •  High transmission temperature (>140?*)
  •  A diagnostics trouble code

The last one can be many things, but the beep pattern may help diagnose it.

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Folks above are correct, there are no codes for the IAC. I adjust the pintle, by turning, to match the old pintle rest position (baseline) before installing, that's all. Service mode is activated by jumping A & B with engine running. Diagnostic mode with only the key on.  Pull your code before opening your wallet.

Edited by electricjohn
Baseline added
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Thanks for the help. I took a little from each you to find the answer. PG 410 of the Clymer Manual spells it out. I now ordered a Clymer manual. In the mean time was able to find the page I needed in the Clymer manual on youtube of all places. I am going to try this today. It appears if your installing a new IAC it should be set to 1.1" and you do need to put the engine into service mode. 

 High engine water temperature (NOT dash sensor, and >203*) - Happens when boat first starts and never makes it to full temp

 Low oil pressure (NOT dash sensor, and <6 PSI) Replaces the small oil pressure sensor

 High transmission temperature (>140?*) Happens within 5-10 of startup so I assume trans temp is not up that high yet

 A diagnostics trouble code - Could be a code but how would I know without a reader? 

If this does not work it may be time to fork over a bunch of cash to the dealer and wait forever to get a boat back. 

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Question 1: From the description in the Clymer manual can I assume a small wire is inserted into the pockets of the plug still on the boat. A/B

Questions 2:  There is a single wire coming out of location K on the plug / cap that I removed. It does not connect to anything currently. Should it?

I would add pictures but there does not appear to be an option for that. 

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7 minutes ago, Bass Lake Skier said:

Question 1: From the description in the Clymer manual can I assume a small wire is inserted into the pockets of the plug still on the boat. A/B

Questions 2:  There is a single wire coming out of location K on the plug / cap that I removed. It does not connect to anything currently. Should it?

I would add pictures but there does not appear to be an option for that. 

1:  Yes, that's it.

2:  I think that wire should be attached to anything to keep the cap from getting lost while you have it off.

A sticky post elsewhere on the site tells how to post photos.

You can build an LED blinker to blink out any codes, or you can build a MEFI cable to read your engine data.  Software for MEFI4 is available.  Start roughly at this post:

 

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  • 2 weeks later...

I hate it when people don't come back and post solutions that worked for them. I replaced the plug wires, plugs and Throttle position sensor. This finally fixed my issue. Because I did not install them independently I am not sure which was the solution. The TPS seemed to have some gummy crap in it but the plugs and wires were also due to be replaced. Hope this helps someone. Both are very easy to replace and literally a unbolt and bolt back in job. 

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