tach not working

Johnson 200 hp v6 outboard,was changing Perko switch and replacing battery to 2 battery's wires touched heard pop, now no tach,/ gauges in tach all work idiot lights work, also cannot get motor to start on #2 battery ,on #1 and all on switch works fine, there is a 40v relay that has 2 diodes in it but manual says they work intermittingly,

Re: tach not working

If your tach doesnt work test the rectifier.

To test the rectifier.....

Place meter in Hi ohms position

1. Disconnect rectifier lead from terminal block. Connect one ohmmeter lead to either yellow or yellow grey rectifier lead, and other meter lead to ground. Note reading

2. Reverse leads, and note reading. Infinite or very high reading in both checks indicates diode open. zero reading in both checks indicates diode is shorted. Normal diode will show a reading in one direction and no reading in other.

3. Repeat with other rectifier yellow lead.

4. Repeat test, connect meter between rectifier yellow lead and rect red/purple lead. Between yellow/gray stripe rectifier lead and rect red/purple lead.