03 merc 25 tach prob

[capped]

hey guys, i have a 25hp merc that i recently hooked a tach up to. There was a gray, purple and black wire underneath my console that i used to wire it up. Took it out today and of course it didnt work, other then having a bad tach out of the box, what other problems should i check for before i try a new tach. Thanks in advance.

 

[Laddies]

Re: 03 merc 25 tach prob

Switch the gray wire on the rectifier to the other yellow terminal or test the rectifier

 

[Barnacle_Bill]

Re: 03 merc 25 tach prob

Check the purple wire. There should be 12V on it with the key on. Check the black wire. It should go to ground. The gray wire comes from the stator via the rectifier. If the rectifier is bad, your tach will not work. A quick check for it is check the voltage at the battery with the motor off. Then start the motor and you should see an increase in voltage.

 

[capped]

Re: 03 merc 25 tach prob

thanks guys, i will look into these things.

 

[capped]

Re: 03 merc 25 tach prob

Hey all, just wanted to say that i had some time to look around in my motor and have some more questions. I followed the grey wire and i cant seem to find where it plugs in on the rectifier but it is plugged into a flat piece of plastic along with black wire. The part # on the plastic is 17461A11 which identifes it as a tach module. Is this something that can fail? And am I missing something without seeing the grey wire run into the rectifier? Btw my model # is 1025312AD. Thanks in advance.

 

[capped]

Re: 03 merc 25 tach prob

anyone?

 

[film495]

Re: 03 merc 25 tach prob

Did you check the purple wire for voltage with a multimeter? Can you also elaborate on "it does not work" ? Does the needle go to zero when the motor is on - or does it do nothing? usually you'll see the needle blip a little when the accessory is turned on as that is what the purple wire that you connected is - power. Any power? or is it just reading wrong?

I have a 25 hp merc 2 stroke that I rigged a tach to that I have yet to fully test, but I just did this whole process.

 

[capped]

Re: 03 merc 25 tach prob

It zeroes out when first started then just moves a bit off of zero and just rests there. I'm not really getting a reading at all.

 

[shawnc]

Re: 03 merc 25 tach prob

I'd like to hook a tach up to my 04 25 hp merc 2 stroke. Is the grey wire connecting to the motor or control box? I am moving this 25 hp to a different boat. It is used as a kicker on my tracker, so no guages hooked up on that one and I haven't had a chance to look at the control box to see what's inside.

The boat I am moving it too has a tach, but it's pretty much junk. Current tach has blue (seems to be for backlight, as all other blue wires are wired with "courtesy lights"), purple, grey and black.

I wasn't sure if any tach will work or if I would need a mercury specific tach.