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Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 15920
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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I have 2003 mercruiser 6.2 engine the ECM wen bad, and we

Customer Question

good morning
JA: Hi. What seems to be the problem?
Customer: I have 2003 mercruiser 6.2 engine the ECM wen bad, and we found a ECM from a 2005, it reads all functions on the smartcraft gauge but does not fire up, the distributor on the 2003 has a cam sensor pickup coil but no harness on the engine so is blank..
JA: Sometimes things that you think will be really complicated end up being easy to fix. The Marine Mechanic I'm going to connect you with knows all the tricks and shortcuts. Is there anything else important you think the Marine Mechanic should know?
Customer: im guessing the NEW ECM is from a newer motor and is looking for the signal from the cam sensor
Submitted: 11 months ago.
Category: Boat
Expert:  Jason replied 11 months ago.

Hello my name is ***** ***** am I speaking with?

I read what you wrote. How is it I can help you?

Customer: replied 11 months ago.
Hello Jason ,First i would like to know if my guess is correct, what is diferent on ECM 555 from 2003 for one 2005?
Expert:  Jason replied 11 months ago.

It's not quite that simple. There have been dozens of different ECM555's over the years. Did you make sure that you had the correct ECM by looking up the part number for it by the engine serial number?

Customer: replied 11 months ago.
my motor is 2003 6.2 horizon bravo FWC, the ECM i got is from a 2005 6.2 FWC bravo, we tried on my friends boat ( 2007 6.2 Bravo ) and works fine we check all wiring on my motor and is fine ( i have twins so i swaped the ECM and the engine runs perfect ) the only thing that will preven the engine from runing i think is that the ECU is searching for the signal for the pick up coil or cam sensor ( not sure how you call the sensor inside the distributor ). the 2007 engine has the plug but my 2003 engine does not. Seem to be position A4 on the ECM
Expert:  Jason replied 11 months ago.

Nothing Mercury is done by model year, it's all done by serial number. What is the serial number on your engine, and what is the part number on the ECM you got. I can look it up to see if you have the right ECM or not.

Customer: replied 11 months ago.
my engine serial number is ***** the ECM that i had was 865008-002 864916, the new ECM 0501 is 866130-002 865926
Expert:  Jason replied 11 months ago.

Okay you have the wrong ECM for your engine. 865008T03 is the part number on the ECM that you need. 866130T01 is not the correct ECM, that is for another engine. You will need to get the correct ECM for your engine.

Did you have any further questions on the issue or does that cover it for you?


Customer: replied 11 months ago.
Jason , thanks for the answer, It is obvious since the engine does not run.., however the only difference on a 2003 and a 2007 mercruiser 6.2 is the pickup coil on the distributor, so the only thing that will keep the engine from runing will be that. Im trying to identfy the wires conected to the NEW ECM that com from the pick up coil so that i can add them to my harness and make the engine run .
Expert:  Jason replied 11 months ago.

.., however the only difference on a 2003 and a 2007 mercruiser 6.2 is the pickup coil on the distributor

Are you sure about that?

Customer: replied 11 months ago.
we looked at both engines harness and components ans yes, that is the only diference that we can see obvious,
Expert:  Jason replied 11 months ago.
Here, i'm adding a picture for you. This comes from Mercurys dealer network. You can see how many different ECM's there are for small block chevy V8's. I have no idea what the differences are between each ECM, but they are all different. If they were not different, then Mercury would simply use the same ECM for every small block. There are also more ECM's that what is in this picture. (probably 30 or so more different part numbers than what you see in this picture). See attachment.
Expert:  Jason replied 11 months ago.

Each different part number ECM is unique. Different engines work different ways. The outer casing of the ECM's may look the same but the circuit board inside of it are different. I can tell you that this has nothing to do with a cam sensor. The engine doesn't need a cam sensor to run. The reason for a cam sensor is so that the engine starts quicker. The engine needs a crank sensor in order to run. If the engine had just a crank sensor, it would take 3 or 4 revolutions of the engine before the ECM knew what the position of the crank and cam shafts where. On engines that have cam sensors, what those are for is to allow the engine to start quicker than it normally would with just a crank sensor. Engines that have just crank sensors take 3 to 4 revolutions before the engine will attempt to start. Engines that have both crank and cam sensors can start in under 1 revolution. After looking at the picture I added, does that all make sense to you.

Customer: replied 11 months ago.
Jason ,Yes there are many ECM that mercury build.. However internal combustion and principles are the same for most of them . IE if you take a 2008 350 mag and a 2010 350 mag, all parts are IDENTICAL for combustion ( it may have different alternator, water pumps pulleys) they both have diferent ECM part number and if you swap them out they both run identical. Im not getting the answer I need. I appreciate your help .
Expert:  Jason replied 11 months ago.

in the picture I gave you, you can see there are 17 (if I counted right) different ECM's just in that picture alone. Only 1 of them will work with your engine. I can also tell you that there are probably closer to 50 in total different 555 style ECMs. But only 1 will work correctly with your engine. If they all "could" work, Mercury wouldn't have to have 50 different ones made.

Expert:  Jason replied 11 months ago.

I'm trying to help you out and save you a headache. The ECM you have isn't going to work. It's up to you if you want to believe me or not. If you don't, then you are going to be in for a big surprise when you learn this the hard way.

I don't know how you want to leave this but that is where you stand on your end and what you need. I think that should do it but I work for tips so I do want to make sure you are happy with my service before you go. If you had a further question on the issue by all means feel free to ask. If not, Just in case you do not understand the way the website works (and some folks do not). You do have to put forth a positive rating in order for it to credit me for helping you. When ratings are not done, the website simply keeps your deposit and they will not credit me. The ratings box is located at the top of the screen. To rate, you must select the star you wish and also confirm it. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, or if you can not see the ratings box which is at the top of the screen. Please reply back "I rate Jason's service _______" and fill in the blank.

Questions do not close out, so if you have to come back later on with follow up questions to the issue you still can even after doing a rating.

Thank you

Expert:  Jason replied 11 months ago.

It looks like you read my answer without replying back or putting through a rating for me. Please keep in mind the website did charge you to speak with me, but they will hold your money and not credit me for helping you out if no rating is put through. If you have a problem with the ratings box or can not see it please let me know.



Customer: replied 11 months ago.
Have a good weekend . Jason .
Expert:  Jason replied 11 months ago.

You to.

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