How to check ECM

BIGALF1

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Is there a code that determines if the ECM is 100% working ? My 5.7EFI Throttle body has an alarm the my go on sometime and then a reduced speed will follow. This does not happen all the time.So far all systems were checked or replaced and I thought it was fixed. It ran great for 3 outings then the last time it did what it was doing for the past year. I would run for awhile then the alarm would sound and the engine would slowdown. I would say limp home mode (guardian mode) but I'm not sure now what the problem is. What is the life of a computer ECM?
 

alldodge

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Is there a code that determines if the ECM is 100% working ? My 5.7EFI Throttle body has an alarm the my go on sometime and then a reduced speed will follow. This does not happen all the time.So far all systems were checked or replaced and I thought it was fixed. It ran great for 3 outings then the last time it did what it was doing for the past year. I would run for awhile then the alarm would sound and the engine would slowdown. I would say limp home mode (guardian mode) but I'm not sure now what the problem is. What is the life of a computer ECM?

Is the alarm constant or beeps?

Also what year or engine serial number is this?
 

BIGALF1

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My engine is a 1997 Mercruiser 5.7EFI with a replaced engine by Mercruiser put in 2007. It is a solid beep when it goes on. The service guys is checking the whole system and so far is confused with what is not working correctly.
 

thumpar

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The alarm will go off solid for oil pressure, lube monitor low or overheating. You can disconnect the connectors to each when the alarm is going off to find out which one it is.
 

Dshow

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Can't you read the codes from the ECM to tell what the issue is?
 

alldodge

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My engine is a 1997 Mercruiser 5.7EFI with a replaced engine by Mercruiser put in 2007. It is a solid beep when it goes on. The service guys is checking the whole system and so far is confused with what is not working correctly.

As Thumper stated, the solid alarms and a couple more listed below
[FONT=&quot]1.) engine coolant temp overheat,
2.) low engine oil pressure,
3.) engine overspeed,
4.) exhaust manifold cooling temp overheat
5.) sea pump PSI low. [/FONT]


The seawater pump pressure switch is the most common fault. The switches go bad all the time or they can have a bad connection. The water pressure switch does not throw a code, just like the others.
 

thumpar

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Was the replaced engine a replacement for the original or was it a new 2007? Maybe a serial number would help. The engine in my boat was replaced in 2002 but uses all the same 1996 equipment.
 

Fun Times

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Seems like a lot of our questions might be found in BIGALF1's other topic linked below. Looks like he had a new block installed but used the same parts from his 1997 engine so he should have a MEFI 1 or 2 style ECM. If so, he should have less items to sound the warning horn than a 07 engine model.

http://forums.iboats.com/forum/engi...board-engines-outdrives/7837499-loss-of-power

BIGALF1, any chance of posting a photo of your engine control module (ECM) to confirm what ECM you have? Also have you checked your spark plugs to see if they seem fouled? You may have an intermittent sensor problem. A MAP sensor may show signs on the sparks plugs should it be going rich.

What has been inspected & changed since the first time you had the warning horn go off?
 

camalot

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The ECM are/can be odd things when it comes to fault codes, even thou you have an older ECM the wiring harness will be the same as a newer model. What I have found is constant alarms are not stored as a fault code always. Your have to get your tech to come out with you and read the guardian mode as it happens. It may cost you $$ or even $$$ but he/she will be able to read it as it happens and take all the guess work out of it. As pointed out it maybe low block pressure ie your seapump which would send you to the sensor as they are junk and always go wrong.
 

thumpar

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The early EFI systems don't have the seawater pressure sensor. I would look toward the sensors I posted above.
 

Tail_Gunner

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My engine is a 1997 Mercruiser 5.7EFI with a replaced engine by Mercruiser put in 2007. It is a solid beep when it goes on. The service guys is checking the whole system and so far is confused with what is not working correctly.

Could you be more spefic here...Who are the mech's did they retune the ecm...that's reprogram

https://drive.google.com/file/d/0B3w...it?usp=sharing

That should help some
 
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BIGALF1

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Just an update. MAP Sensor was replaced and new Spark Plug cables were installed. boat ran fine today. Who knows what will happen the next time out.
 
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