914 TACH"s do they fail ?

[abc123]

have 1974 914/2.0 ,,the tach does not work, do they fail? the wires on the back are red/white that must be power, then the middle wire is black and the one on the far right is brown (ground) the BLACK wire were does it get it's impules form ? my coil has 2 wires one for ground and one to the DIST is that correct ? shoud there be a 3rd wire for the TACH ? I do have another tach to try thanks in advance for help

[Dave at Pelican Parts]

The tach signal wire should be black with a purple stripe. The purple can fade and be a little tough to see, especially in the engine bay. That wire should plug into the (-) terminal of the coil, along with the green wire from the distributor. There would be one wire plugged into the (+) terminal of the coil, and that is the power supply wire. It is plain black, or black with a red stripe, and is thicker than the tach signal wire.

On the gauge side, the black/purple wire should plug into the "G" terminal, which may also be numbered "1". The brown ground wire would plug into the terminal with the ground symbol (three parallel lines), and the power to terminal 15.

Tachs can fail. They can be rebuilt for a pretty good chunk of change, or be replaced with one from another 914. Make sure you use the same type as the one you have, likely the mid-74 and later type. The main difference is the silver cone in the middle of the earlier tach and the two turn signal indicators instead of one. (The 74+ cars aren't wired for two indicators.)

--DD

[abc123]

I have 3 wires on the coil and they are hooked up right I have a 73 tach can I replce the 74 tach with a 73 ?

[Dave at Pelican Parts]

As I said in my PM, yes. It may not look quite correct (the silver cone in the middle) if your 74 doesn't have all early-style gauges.

The very early 74s used 73 gauges, but the 74 wiring harness. Someone at the factory installed a jumper so both turn signal indicators would blink when either turn signal was on.

--DD

[larrym]

i have a nice 4-zyl tach available - early silver button - 914-641-302-10

p.m. for picture

.

[larrym]

Dave

- how does one undo that jumper so you can have individual blinkers?

I am looking at the back of my spare tach

- it has a black/white to the RT bulb, feeding out via blu/wht to the LT bulb, which has blu/wht & black/grn feeds into it

Originally Posted by Dave at Pelican Parts

As I said in my PM, yes. It may not look quite correct (the silver cone in the middle) if your 74 doesn't have all early-style gauges.

The very early 74s used 73 gauges, but the 74 wiring harness. Someone at the factory installed a jumper so both turn signal indicators would blink when either turn signal was on.

--DD

[Dave at Pelican Parts]

Originally Posted by larrym

- how does one undo that jumper so you can have individual blinkers?

You don't, at least not with the 74+. You'd have to do a bunch more wiring to get them to blink individually.

--DD