GT40 Power to ECM

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   I was in the Engine Manual that came with our 95 Skin Nautique today while I was working on my Starter.

I read in the manual that the ECM on a GT40 is wired to stay powered at all times because the ECM stores memory and tunes the engine while it runs and keeps this data stored in the ECM for future use.  Makes sense.

These boats also have an Ignition switch on the dash which I always thought killed all electrical in the boat and which I shut off after every use to avoid battery drain.

Can anyone tell me if turning the Ignition switch off also kills power to the ECM?
I am curious if I have been clearing out memory in the ECM.
The boat always has run great so I suspect it has not lost memory but over the winter I normally will disconnect the battery.  Today I disconnected the battery to remove the starter, I would think disconnecting the battery for sure will earase the ECM memory and cause it to Re-Learn it's tune again?
I did not see any notes on how long the ECM takes to learn a tune.

Do you guys have any experience or thoughts on this, no rush as nothing is broken this is just a curiosity.

Thanks
Mark

Mark

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MrMcD Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3591	Post Options Post Reply Quote MrMcD Report Post Thanks(0) Quote Reply Topic: GT40 Power to ECM Posted: July-08-2019 at 10:16pm
	I was in the Engine Manual that came with our 95 Skin Nautique today while I was working on my Starter. I read in the manual that the ECM on a GT40 is wired to stay powered at all times because the ECM stores memory and tunes the engine while it runs and keeps this data stored in the ECM for future use. Makes sense. These boats also have an Ignition switch on the dash which I always thought killed all electrical in the boat and which I shut off after every use to avoid battery drain. Can anyone tell me if turning the Ignition switch off also kills power to the ECM? I am curious if I have been clearing out memory in the ECM. The boat always has run great so I suspect it has not lost memory but over the winter I normally will disconnect the battery. Today I disconnected the battery to remove the starter, I would think disconnecting the battery for sure will earase the ECM memory and cause it to Re-Learn it's tune again? I did not see any notes on how long the ECM takes to learn a tune. Do you guys have any experience or thoughts on this, no rush as nothing is broken this is just a curiosity. Thanks Mark Mark

gt40KS Members Profile Send Private Message Find Members Posts Add to Buddy List Gold Member Joined: August-05-2017 Location: Wichita Kansas Status: Offline Points: 943	Post Options Post Reply Quote gt40KS Report Post Thanks(0) Quote Reply Posted: July-08-2019 at 11:59pm
	Hmmm..... Good question Mark. I guess I'm in that boat as well because I completely rewired mine and added the battery switch that most definitely cuts off all power. I do seem to recall reading something similar at one time though. I guess I was under the impression that it was a short-term sensor reading flash that it uses for brief, intermittent tune changes and resets itsself every time you shut down the engine.
	JCCI 1995 Ski Nautique GT40

MrMcD Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3591	Post Options Post Reply Quote MrMcD Report Post Thanks(0) Quote Reply Posted: July-09-2019 at 5:43am
	I will try and post a picture of the statement in the manual. This is in the Engine Section of the Manual delivered with my boat when it was new. It talks about the KAM or Keep Alive Memory to help tune a GT40. I also noted in this manual that all GT40 engines are 8.3:1 compression ratio. Now I am thinking Aluminum Heads with smaller chambers and better flow may help these engines a lot!!! If not different pistons and close to zero deck. But it runs so darn good as is, maybe PCM had a good plan for a reliable boat engine. After 30 minutes of trying I think the photo has attached from my MAC for the first time. A 30 second job on my Windows based computer. I have a lot to learn on the MAC.

gt40KS Members Profile Send Private Message Find Members Posts Add to Buddy List Gold Member Joined: August-05-2017 Location: Wichita Kansas Status: Offline Points: 943	Post Options Post Reply Quote gt40KS Report Post Thanks(0) Quote Reply Posted: July-10-2019 at 1:33am
	Interesting Mark. I believe that's the passage I read as well but thinking now I more skimmed it since I obviously misinterpreted the content. I wonder which is the KAM power wire and if it can be separated from the bundle - or if it already is - so it could be routed to one of my batteries at this point.
	JCCI 1995 Ski Nautique GT40

MrMcD Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3591	Post Options Post Reply Quote MrMcD Report Post Thanks(0) Quote Reply Posted: July-10-2019 at 2:52am
	I am wondering the same thing, I think I will run the boat this weekend, we will be on a 5 day boat trip, if it runs great I may forget about the ECM memory and drink a cold one! Hope to get in the first ski of the year, Christ, it is mid July, hard to believe that can be a true statement. We used to get out 3 times per week weather permitting. If I get bored when I get back I may try and read the electical diagram and see if it shows the power source for the ECM and KAM.

GT40 Power to ECM

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