2002 EFI 115 4-Stroke Tachometer not working

[mbhoag]

My meter is old school, but has outlasted several digital multimeters...

It is a Sperry Mulitmeter SP0140 .. I think I got it new in 1979... still works awesome.

I do also have an inexpensive DVA adaptor....

 

[sam am I]

Yes, put that DVA on the tach's signal converter input (ECU's tach output, etc) crank it up and see what she reads..........Might be 5V or 12V peak, not sure. If you get something on the input, go to the output see what ya get...

 

[mbhoag]

Yes, put that DVA on the tach's signal converter input (ECU's tach output, etc) crank it up and see what she reads..........Might be 5V or 12V peak, not sure. If you get something on the input, go to the output see what ya get...

Well, water pump kit came and I replaced the whole kitten kaboodle! Fired her up and did this test...
Got between 4 and 5 volts AC on the input wire to the signal converter, but got ZERO volts on the output. I am guessing that the signal converter is bad! (even though I replaced it last year to try and get tack working). Either bad converter or it burned out for some reason...

I did order a new one last week, so it should show up shortly and I will know for sure.

 

[mbhoag]

Well, replaced tach signal converter (see pics). The old one you can see the splices, and it appears that it was installed with signal input & output wires reversed.

New one installed corrected (as per wire color coding AND Mercury wiring schematics)

I now have:
5 volts (AC using DVA) on green input wire
1 volt (AC using DVA) on grey signal output wire
1 volt (AC using DVA) on grey signal output wire confirmed at tachometer
Power and ground also confirmed at tachometer.
I verified that the tach was correctly set for 12 poles!

The end result...... (drum roll please)
The damn tachometer STILL DOES NOT WORK!

It does the usual fluctuation when key is turned on, but it does NOT show any RPMS!
The hour meter on does continue to work...

So, could the tach I installed last year now be bad/burnt out because of the signal wire being backwards (or some other issue?) How can I tell for sure that I need a new tach VS some other issue?

I still need more suggestions! arrggghhhh!

 

[mbhoag]

No more ideas from anyone?

 

[Tommyorrison]

Check all the wires bundled together coming off big connector i had 3 wires corroded inside connector and 1 black wire that had no wire for 3 inches but the jacket was good fixed all those and tach started working

 

[mbhoag]

Check all the wires bundled together coming off big connector i had 3 wires corroded inside connector and 1 black wire that had no wire for 3 inches but the jacket was good fixed all those and tach started working

Thanks, will double check that. Pretty sure those wires are all OK as I Ohm'd each of them from the big connector to the tach itself, and they all checked out fine... might try a temp bypass wire just to make sure..

 

[jSPECx]

Did anyone ever figure out what was wrong with it? I'm having the same issues. Took it to a certified mercury dealer in town. And the replaced everything you mentioned, stator, rectifier, rpm tach, and tach module... twice... I'm getting continuity from green ecu harness to the gray tach signal upfront.

How do i text the tach module. Maybe i got two bad ones in a row.

 

[GA_Boater]

Please start your own thread. This one has been inactive for almost a year.

Closed.