Tach issue

[wilbur1]

Its a 2015 115atlss. The tach works on smooth water,but when you hit a wake it goes to zero and then back to normal rpms. Sounds like a loose connection but everything is tight under the dash. Where do these tach wires connect on the engine.? Thanks for any help.

[wilbur1]

This is the tach. Click pic to enlarge.

[Moonlighter]

Engine harness connects to the ecu output in the engine. 4 pin plug near the fuse box.

Did you check all the harness connections from the dash thru to the throttle controls?

[wilbur1]

You mean in the same area where the SDS connects.? Im confused with throttle controls, mine are cables. Thanks Moonlighter

[Moonlighter]

Yes near the SDS plug is the main harness connector - if you run analogue gauges harness will be connected there. Same size plug as SDS.

Harness runs through transom and then up to the engine controls where you start the engine, and then to the dash for instruments.

Trace cables from tacho back towards engine controls see if any wires have been damaged or plugs corroded etc. Anywhere they pass through holes bulkheads etc check for damage from rubbing etc?

[wilbur1]

All plugs look good. Im thinking there is a stud somewhere that the ground connects to but cant locate it. This is a Center Console and its hard laying on your back and reaching way up in there. Would it be possible the Ground runs back to the engine.? If so where do you think that would be. Thanks for your help

[wilbur1]

Think I might of found it. There was a Yellow wire coming from the Tach harness that was partially unplugged. Will find out next time I go out. Thanks
Would the Yellow wire be the one to cause the problem.? Book says y/b