Tach Problems Wiring Diagram

"I removed my tachometer the o

"I removed my tachometer the other day because it didn't work, at all. Unfortunately I failed to label the wires when I took them off. Black, Grey, and Purple wires were attached to it.

The new teleflex tachometer (in a MARPAC branded package) said that it should "go to zero" when the power is turned on.

I connected the black to ground, and I've tried the other two wires both ways (coil and send) and neither causes the tach to "go to zero" when I turn on the ignition.

Now, I haven't actually run the engine yet (doing so this evening) so who knows what'll happen.

But I couldn't find a valid wiring diagram that describes the purple and gray wires.

My boat is a 1985 Glastream Cutlass 172 with a MCM140 Mercruiser engine and an alpha one stern drive."

"(and yes, I realize faili

"(and yes, I realize failing to label my wires was a mistake).

What happens when I power on - the tach goes down the first time but only to about 700 RPM. If I turn the ignition on and off numerous times, it goes up a little bit each time to as high as 1000 RPM.

It behaves exactly the same way with the gray and purple wires reversed."

"Heh. Never mind.

[url=""]

"Heh. Never mind.

http://www.boatfix.com/merc/Servmanl/13/13E4R2.PDF

I found the wiring diagram in Service Manual #13. Purple is "Ignition" and gray is "sender"

My tach is labeled "Coil" and "Sender" but I guess coil is the same as ignition =)"

Rick;
Good luck.
I think you

Rick;
Good luck.
I think you have it correct.
It's nice when a plan comes together.

Rod

"update: tach seems to work n

"update: tach seems to work now that I've got it connected properly. It goes to zero like it should and read about 500 rpm (ish) at idle. I don't like putting much gas on when I'm not in the water so I didn't really test much beyond that.

Oh, I also had it set to 4 pulse which is why it wasn't working.. changed it to 2 pulse 4 cylinder and it works =)"