Help Wrench! Etec keeps blowing fuse?

[fishinwrench]

To my knowledge there is nothing inside the module that can short the ignition ON circuit to ground.    The only thing that does it INTENTIONALLY is the key switch or kill switch....and that portion is unfused. 

The most likely cause, I would think, is the wire under the console that powers up the gauges.....since they get TINKERED WITH when installing sonar units and such things.   

There is a TSB on the exhaust valve relay......I guess that ONCE UPON A TIME a relay shorted out and caused the 10a fuse to repeatedly blow during acceleration on a SALT WATER motor.   But even that wouldn't blow the fuse simply by turning the key switch ON.     

It's most likely going to be something simple and stupid to repair, ya just gotta figure it out. 

[fishinwrench]

I'm sure that alot of EMM's have been sold where the tech replaced it, it still blew the fuse, and then they FINALLY discovered the REAL REASON, repaired it in 3 minutes.....and then just let the customer assume it was truly an EMM failure......to cover all the time they wasted on it.    

Then the perfectly good EMM gets thrown in somebody's truck, goes home with them, and ends up on eBay 😂

Cuz that's how $#!t works in this business sometimes.   

[BassMaster#1]

9 hours ago, fishinwrench said:

I'm sure that alot of EMM's have been sold where the tech replaced it, it still blew the fuse, and then they FINALLY discovered the REAL REASON, repaired it in 3 minutes.....and then just let the customer assume it was truly an EMM failure......to cover all the time they wasted on it.    

Then the perfectly good EMM gets thrown in somebody's truck, goes home with them, and ends up on eBay 😂

Cuz that's how $#!t works in this business sometimes.   

Totally hear you on that one and really appreciate you answering my questions.  So this evening I went to the motor and disconnected all the red/white harness just to check and see if something there was an issue.  Think it was 3 harnesses for fuel injectors and 3 other harness for coils or something?  Fuse still blew so come tomorrow I will disconnect all purple harness wires connected under the console.   I still think I have some short or something coming from under that dash to the tac or something.   I can say that I am learning a lot about this motor just from getting my hands dirty with it.  Since I can't get it to the shop for a few weeks I'm trying to diagnose as much as I can and don't want to be told I need a computer when I may not. Thanks again

[BassMaster#1]

Just to close this out checked everything I could possibly check and just not coming up with anything.  Even came across this website where multiple folks would say unplug the 3rd harness (J-3) harness and turn the key.  If it dosnet blow when unplugged but blows when that harness is plugged back in then it points to the computer being bad.  Need to check my engine harness but thinking about sending this computer of for repair/rebuild.  Thanks

[fishinwrench]

Did you ever hook an ohmmeter up to the purple wire? 

[fishinwrench]

On 5/24/2021 at 11:23 AM, fishinwrench said:

You should be able to hook up an ohmmeter from purple wire to ground....and then start disconnecting harness plugs until you get an infinity reading, and that will tell you which portion of the harness the problem lies.  But first you will have to disconnect the purple wire from the key switch because the purple wire is always grounded through the key switch when the switch is OFF....

 

[BassMaster#1]

47 minutes ago, fishinwrench said:

 

Well that is the only thing I am a little confused on?  Do I check the purple wire at the ignition or the harness at the motor.  Guess I'm a little confused as to where to check the purple wire?  Also does the key need to be in the on position when checking the wire?  Should I be seeing 12volts on the ohmmeter? Thanks

[fishinwrench]

1 hour ago, BassMaster#1 said:

Well that is the only thing I am a little confused on?  Do I check the purple wire at the ignition or the harness at the motor.  Guess I'm a little confused as to where to check the purple wire?  Also does the key need to be in the on position when checking the wire?  Should I be seeing 12volts on the ohmmeter? Thanks

An ohmmeter tests continuity, you're not looking for voltage, you are trying to determine WHERE the short to ground is.   

If I were doing it, I would disconnect the purple wire from the key switch and clip the red lead of the ohmmeter to that purple wire....then connect the black ohmmeter lead to the main ground at the engine block (or the negative terminal of the battery).    

What you want (need) to see is "0" indicating NO CONTINUITY.    But it's likely that you are going to see a degree of continuity.    Start disconnecting harness plugs, from the engine moving forward towards the key switch, one at a time, until you see "0".....and then you'll know where the short to ground is located at.   Narrowing your search area. 

You can then move the red ohmmeter lead to THAT SPOT....and locate it even closer.....if you need to.

If you make it all the way from motor to key switch without getting a "0" then you'll know that the short is not at the engine.....and that leaves the guage panel.....so go there.