DF300 code 4-2, need a ECU?

[knotreel@hughes.net]

Checking my boat for a trip, port engine ran on the hose and warmed up properly. The star started and after a few minutes got an overheating alarm but dash gage was showing 99f. One bank felt about 99f, the other felt like it might have been 130-140, certainly not 180. After discovering the engine was not actually overheating, I tried to restart and now code 4-2. I think starter spun at first then no start and no spin. So the book says the CKP sensor should have 180-252 ohms, mine has 208ohms,. so that's good, I guess. Also the reading is the same at the ECU plug making it not look like a harness issue, to me. I swapped the ECU's and the problem went to the port engine when it had the star ECU and and star engine runs with no alarms wwhile it has the port's ECM . Normally I would say, Bingo!, but a new ECU is 1700-1800 bucks and could not find used one. My question is, finally, could this be something else? Any ideas?

[Murray]

Not many reports of a blown ECM on this forum. Not saying it isn’t blown, just an observation. At the top of this page select the tab “Buy Suzuki Outboard Parts” find your ECM and scroll down to the bottom, there will be a list of all engines that share the same part. Will give you more models to search for. Might be worth a trip to a Suzuki shop, they have a diagnostic tool (SDS) that should be able to check your suspicions. Sorry I couldn’t be more help.

[Handsomerob1980]

I'm an Automotive mechanic by trade not a marine mechanic, however your diagnostic process seems correct, you have isolated the issue to the module. The big question is is it a hardware fault or did the software just glitch. I'm not sure if they can re-flash the ecm or not but I would make a call to a dealer to see if it's an option.

[knotreel@hughes.net]

well, thanks for the info on part interchange, might be helpful,
I might call a dealer as suggested but in the meantime I plunked down a lot of $$ for a new ECU. Maybe the re-flash, if possible, can give me a spare. The batteries were a little low which I should know better than to proceed but the port engine was started first and ran for 5-10 minutes before I stared the star, but still that could have been the what caused this. \
I was bent toward the purchase of the new ECU because there was also the phony high temp alarm as well as the error code 4-2. It seems that 4-2 can also be for neutral shift switch too? I am a little confused by the SDS. I don't have much (any) experience using it but after main menu all I can get is BCM module functions., Maybe later I'll try hooking the SDs to the engine. I was thinking that all should be on the can buss no matter where the square 4 wayplug is hooked.
I "heard" that the new computer had to be initialized, or something, but I am guessing that is done by initializing the BCM.

[Moonlighter]

well, thanks for the info on part interchange, might be helpful,
I might call a dealer as suggested but in the meantime I plunked down a lot of $$ for a new ECU. Maybe the re-flash, if possible, can give me a spare. The batteries were a little low which I should know better than to proceed but the port engine was started first and ran for 5-10 minutes before I stared the star, but still that could have been the what caused this. \
I was bent toward the purchase of the new ECU because there was also the phony high temp alarm as well as the error code 4-2. It seems that 4-2 can also be for neutral shift switch too? I am a little confused by the SDS. I don't have much (any) experience using it but after main menu all I can get is BCM module functions., Maybe later I'll try hooking the SDs to the engine. I was thinking that all should be on the can buss no matter where the square 4 wayplug is hooked.
I "heard" that the new computer had to be initialized, or something, but I am guessing that is done by initializing the BCM.

Multiple false codes - the first port of call is ALWAYS a voltage issue (amperage actually). So this would prompt a examination of the battery, battery connections, white wire connection.

[knotreel@hughes.net]

Gonna buy two new starting batteries. they haven't been holding a charge as well as would like and they don't take much amperage when on the charger. Still feel sorta good about the new ECU. but we'll see?

[knotreel@hughes.net]

Well, I was either gonna be a parts changing idiot or a happy fool that bought an 1800 usd ECU. I turned out to be the happy fool. The new ECU will now run in both engines as does the original port side ECU. After I got both engines running, I re-installed the original star "bad" ECU to double check and that ECU fails to function in either motor. I am one who believes, "it's never the ECU", but this time it appears it was. I better catch some tuna and swords to make the 1800 not sting as bad.
Thanks for the comments and help.

[knotreel@hughes.net]

I have some advise that I learned the hard way. Be careful what you spray on the ECU connectors, or probably any other ones too. I sprayed mine during the troubleshooting phase with CRC 6-56 which i use on the engine for corrosion protection but this reacted with the silicone seals of the ECU plugs causing swelling to the extent that I could not push the plug far enough in to get them to lock. I ended up ordering some new plugs and transferring the ecu wires to the new plugs. I thought I was just going to swap the seals out but I couldn't do that.