Electrical issues- dead gauges blowing 20A fuse-solved!

[matth121]

Hey all, so after ressolving my starter and fuel pump issues(carbed 1996 4.3 merc won't shut off with key), i started troubleshooting his non functioning trim gauge. The gauge had worked before the partial submersion of his engine. it now reads full up all the time which i believe means there's an open in the trim sender circuit. While following the wires and moving the harness this way and that looking for wire breaks, i happened to notice that all gauges were now dead, no power and were no longer illuminated. Further investigation led me to the fuse panel under the helm where i found a burnt 20A fuse in the circuit that's connected to the keyswitch. I replaced the fuse and it blew again immediately. I know i have a short somewhere thats causing this but am unsure as to where it might be- i can't find any obvious breaks in the harness, no missing insulation. i know this is a hard one to ask for help, but please, help. any typical wiring diagrams for helm wiring, and thoughts as to common causes of shorts in the ACC circuit. In addition, i'd love to know what color wires run from the engine compartment up to the trim gauge in the helm so i can follow them back to the sensor. Thanks in advance for any help you may be able to provide

 

[alldodge]

Well lets see if this will work
http://www.boatfix.com/merc/servmanl/13/13e4r2.pdf

 

[matth121]

Thanks AllDodge- seems like its limited to 3.0L engines but i think i should be able to get by with it. Only gauge not mentioned is the trim tilt position unless thats what they are calling the "cruiselog"

 

[Bt Doctur]

No, look for trim indicator .powered by purple wire, sender is brown/white

 

[matth121]

ya, i did see that but i know for sure that there isn't a brown/wht wire attached to the gauge, but i'll be looking for it next time i get out to it.thanks

 

[NHGuy]

I'd not concern yourself with the trim wire yet. First you have to get the fuse to hold and the gauges to power up.
If the starter is low on the starboard side like most, it's probably shorted internally from the water intrusion.
Check that first, and check any other electrical parts that got wet.

 

[matth121]

thanks for the advice and i agree- trim gauge is the least of my problems right now but seems to be the only thing anyone wanted to comment on- starter is brand new- alternator is off at the moment and will be replaced this week- only other thing that got wet was the bilge blower and thats also being replaced and is currently removed from boat. no obvious shorts anywhere, no visible cracks in wiring insulation. going to be tough to track down i think

 

[Bt Doctur]

unplug the main harness plug at the engine to help isolate it.

 

[matth121]

That's a fantastic idea! thanks BT

 

[matth121]

Finally managed to track down the short- turns out the purple/yellow wires ring terminal shaft was coming into contact with starter body(ground). reason this was a dead short is that the pressure switch had been bypassed and a jumper was used to connect purple(12V) to purple/yellow so the pump runs as soon as key is turned on and since purple/yellow was shorted to ground- blown fuse everytime key was turned on. With the short fixed- gauges are now all working, even the trim gauge. all i have to do now is replace the oil pressure switch and it should be good. Thanks for all the help guys
matt

 

[NHGuy]

Good for you, at least you didn't have to find a problem between the helm & the engine!

 

[matth121]

lmao- started at the helm- ended up at the engine, was everywhere in between- didnt think about the starter until i had completely ruled everything out, oh well, fixed now