Tachometer reads zero, 96 Super Sport GT40

[Tryathlete]

Had the SS out on the water for first real successful expedition. Previously had alternator belt shatter and had to order a set which I put on. Also replaced main ignition breaker. Noticed tachometer does not work. Does anyone know where I should be looking first? There's no wiring diagram yet on PN for a 96 SS. Could I have pulled a wire loose on the breaker panel when Changed the ignition breaker?

[jhersey29]

I'd check the wires on the rpm gauge. Since you popped the dash off. The ground wires are barely attached with small connectors and easily fall off.
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[Tryathlete]

Horn, tach, and possibly nav lights in op. I want to take the dash off....looks like PO had it off a lot since the big thumb screws that hold it on are loose. Is there anything I need to be aware of before pulling this whole thing off? I'm suspecting several wires simply pulled off, but there's no manual I can find anywhere detailing what to do here.

[Tryathlete]

Yup. Tachometer missing ground wire....must have come loose during stereo installation. Now to chase nav, anchor lights and horn.....all wires at their terminal ends in dash seemed sound. Any thoughts other than chasing their other ends?

[jhersey29]

I'd start with the nav lights. The rear anchor light could be a bulb. the horn is buried in the vent and getting to that requires taking a window off. Sure sounds like a ground issue. Clean the 3 ground points at the block. 2 in the rear, one in the front. Take off the steering wheel and double check the wires and connectors under the dash. Its way easier with the wheel out of the way.
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[vortech347]

Add a relay for the horn so it's not pulling power from the dash. The dash is horribly under powered already. I did that on my 98 Sport and it helped tremendously. Search horn relay on the site. That's how I got the idea.

[Tryathlete]

Thanks guys! Horn inop, but nav lights and anchor lights working....just could not see them in daylight. I did notice after hooking up the loose wire on the tach that it roams a bit instead of reading with total accuracy. Maybe a weak ground...just have to fiddle with it. Everything functioning now other than the horn, and I have a air horn by the driver's seat anyways.

[jhersey29]

Wiggle the 6/8 setting switch back and forth. It is on the back of the tach. Put it back to where it is. Should have mentioned it earlier but forgot. That should resolve the inconsistent rpm reading.
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[Tryathlete]

Awesome tip jhersey29. I can't wait to fix that little bugger! Doing things myself without having to "take it to the man" is so awesome.

[s_kelley2000]

the horn is buried in the vent and getting to that requires taking a window off.

This might be the case in the 02-06 210s or other models but in the 96-01 SS/SAN the horn is easily accessed via the lift up passenger seat. It is right on the back side of the plastic vent circled in the pic. Open the passenger seat, get on your back and look up. As others have said it does sound like a weak ground problem. These boats are known for barely adequate wiring to the dash. Lots of people end up running better ground and power wires to a distribution block by the dash to resolve this issue. There are definitely some threads on here about it if you search.