Mercury 2005 115hp 4-stroke intermittent loss of electrical

[cps22]

I didn't see a similar post so am starting this new one.

2005 115hp Mercury 4-stroke
Purchased new in 2006 with 5-year extended warranty.

Intermittent Symptom occurred six times over the last two weeks:
Loss of most of electrical controls, instruments, starting, etc.
Symptoms eventually go away by themselves, only to appear again a few days later. Very intermittent. While boating on the Wolf River in Central WI, we cruised over 100 miles over the course of a 3-day weekend, about 10 hours of motor operation. The symptom appeared only on the third day while under operation.

Scenario 1: motor not running?.. (occurred 5 times after motor was off for a day or two)
Motor won?t crank over
No power tilt/trim movement
No power tilt/trim display on dashboard indicator
No voltage displayed on dashboard volt meter, shows 0 volts
Accessories (radio, fish-finder,etc) work normally




Scenario 2: Motor running normally, boat cruising at 14mph
No power tilt/trim movement
No power tilt/trim display on dashboard indicator
No voltage displayed on dashboard volt meter, shows 0 volts
Gas gauge stops working
Tachometer stops working
Speedometer stops working
Accessories (radio, fish-finder,etc) work normally


Observations & things tried?..
During scenario 1:
Voltage at battery terminals is 12 volts.
No tilt/trim, no motor cranking, etc
Took engine cover off, thought I heard ?clicking? coming from engine, but not 100% sure, controls on this pontoon boat quite far from engine.

I swapped batteries between this and another boat, symptoms remained.
Purchased and installed a new battery, symptoms remained.


I have a wiring diagram and see a "main relay" shown but can't identify it on the engine itself. Also see that everything is wired into the ECM.

Anyone have any suggestions on where to look. This might be covered under warranty.

Thanks in advance,

CPS22

 

[corm]

Re: Mercury 2005 115hp 4-stroke intermittent loss of electrical

Hi,

Well I know nothing about a engine with ECM on it.
I would have thought a bad battery connection, but you
pretty much covered that. I'm guessing you cleaned the cable ends.
I think you may be headed in the right direction with the main relay.
I could not tell you where it is, sorry.
On another note the Wolf is FUN!

this is more of a "bump" post than help.

 

[cps22]

Re: Mercury 2005 115hp 4-stroke intermittent loss of electrical

I did some more digging into the problem. Again, its intermittent and I can't duplicate it. However, I did find the main relay. I removed the relay to see if I could duplicate the problem, but even with the main relay removed I still had dash volt meter, gas gauge, tilt/trim. So confident now that its not the main relay.

I spent a couple of hours checking every connections within the motor, main harness, under dash, etc. Nothing loose.

I was able to create similar symptoms by removing the 20amp fuse on the motor for the "trim system & key switch". Symptoms were the same as the problem, no dash instruments, no tilt/trim, no cranking. The "hot" side of this particular fuse is connected to the hot side of the other three fuses as well as the output of the regulator. The "protected" side of this fuse supplies power to the trim switch mounted on the motor cowl and into the harness as a red wire.

Anyone have an idea or hint of where else to look for this intermittent problem?

Thanks in advance

CPS22

 

[luredude]

Re: Mercury 2005 115hp 4-stroke intermittent loss of electrical

I had SOME of the symptoms you have/had and my problem was a cracked ignition switch.

Most of the time when I run into an electrical problem it ends up being something really stupid and usually ends up being a bad/intermittent ground.

Hope it helps and hope you find the problem.

 

[rodbolt]

Re: Mercury 2005 115hp 4-stroke intermittent loss of electrical

your scenarios indicate loose connections at the engine, bad battery cables or splices in the battery cables or the pins in the 10 pin harness connector are bad.
carfully check the power tap at the starter solinoid, NOTE this is not the battery positve connection.
carefully inspect the ground lead bolted to the block.
carefully inspect that the battery wingnuts are actually tight, better is replace them with nuts.
its a yamaha with a black dress, main relay has nothing to do with any gauge power up function.

 

[MN_Fishing_Guy]

I am experiencing the exact same thing after having the transom of my boat replaced over the winter. I know this is a very old post - would love to hear if anyone knows the fix for this

 

[GA_Boater]

I am experiencing the exact same thing after having the transom of my boat replaced over the winter. I know this is a very old post - would love to hear if anyone knows the fix for this

8 years is a little old and not one post is from anyone still visiting. Check out our rules and start a new thread.

Closed.