engine and drivetrain tachometer just died

[whiteout]

Driving today and the tach quit on me. Over the past few weeks the tach would jump a little from time to time when engine speed was at a constant.

I've been reading the archives and it looks like it could either be a faulty ground or the cable. Any other suggestions? Any suggestions for pulling the cluster, or what I should be on the lookout for?

Thanks,

Nick

[c.d.iesel]

look at the wires connected - or Not

connected at the coil first

[TobyB]

Check your points,

sparkplugs,

wires and

cap and rotor.

If the trigger (points or p-tronix)

or the secondary system get too

far out of whack, the tach can become

unstable.

When that's not it, follow the single black wire...

hth

t

[Napes]

When this has happened to me in the past it was always the black wire connection to the dizzy. Connection is adjacent to the condensor on the side of the dizzy, and can come loose if bumped while adjusting the dizzy, etc. It's an easy "first check".

Bob Napier

[whiteout]

Check your points,

sparkplugs,

wires and

cap and rotor.

If the trigger (points or p-tronix)

or the secondary system get toofar out of whack, the tach can become

unstable.

When that's not it, follow the single black wire...

hth

t

Thanks!

I will dig into it today. The tach would bounce after going WOT close to redline then shifting to a higher gear and not going WOT. But then settle down. Yesterday, it just died while I was driving (I think I was sitting at a traffic light).

The speedo will jump around from time to time too. Usually at highway speeds. I figured that the speedo cable needs to be greased up. But I do not completely understand how the tach works. I figured it was just a loose cable like a speedo cable.

Nick

[c.d.iesel]

speedo is purely mechanical

tachometer is completely electrical

not related

[whiteout]

. . . and I hate electrical. FML.

Nick

[whiteout]

When this has happened to me in the past it was always the black wire connection to the dizzy. Connection is adjacent to the condensor on the side of the dizzy, and can come loose if bumped while adjusting the dizzy, etc. It's an easy "first check".

Bob Napier

What's the dizzy?

Nick

[spets]

Dizzy = Distributor. shorter/quicker/easier to type.

[whiteout]

Thank you. I was thinking that was the term, but wasn't 100% sure.

Nick

[whiteout]

I found the connection, the tach cable did fall off. So an easy fix. But, I'm not sure if I connected it to the best spot.

The Tach cable is the black wire on bottom tab in the picture. Is that the best spot for it? I tried the tab to the left of it and the tach was very jumpy.

Nick

[HBChris]

It connects to the same coil terminal as the black wire which goes to the distributor. The tach wire is a tiny bit thinner.

[Mike Self]

wire at the dizzy coming loose from its terminal...I discovered that the tach wire is a little short coming out of the wiring harness, and with the M10's flexible motor mounts, it was just pulling out.

I carefully squeezed the female terminal on the wire's end just a little so it was a good tight fit on the dizzy's male terminal, and that solved the problem. So far!

cheers

mike

[whiteout]

I have it re-installed as in the picture above. Everything seems to be working as normal. Woooo!!!!

Nick

[jlandreth]

It happened to me several years-ago and had me stumped.It turned out to be a broken printed circuit trace on the tach mount binnacle.That is probably not your problem however.Good-luck!