Factory Tach ... help!

[T0BASC032]

I sure could use some help with this one. My factory ('77 302) tachometer hasn't worked since I removed the guage cluster to put in some new bulbs.

That was a few months ago, and I figured I must have a bad adapter or whatever that thing is that the connector plugs into that then plugs into the tach itself.

I found the exact same part from the junkyard, and finally got around to puting it in, and then....... nothing.

I've used a test light (when car is running)to see if I'm getting power from the plug, and I do on 2 of the 4 prongs. When I test it with the adapter on I only show power from 1 of those 3 prongs.

I don't know jack about these electical things, but is it possible the actual tach itself is the culprit? Or should I be getting power to more prongs on the connector and/or adapter?

Hopefully somebody has been down this road before?

 

[COBRAIIW]

most likely you got a bad adapter from the junkyard.the darn things are notorious for failure.also,make sure when you get a new one that it's for the engine you have.they are different for 8's 6's,and 4's.
happy hunting!

 

[T0BASC032]

Well, I'm pretty sure I got the only one that is the same out of all the junk II's I've found.

Any idea who might be able test or possibly fix things like that?

 

[jshcobra]

Well, I'm pretty sure I got the only one that is the same out of all the junk II's I've found.

Any idea who might be able test or possibly fix things like that?

As far as I understand it (which isn't very far...) the tach adapters are a fairly simple signal converter which anyone with basic electronic knowledge should be able to diagnose and/or repair. I'd check your yellow pages under radio/tv repair and see if you can find someone willing to take a stab at it. Worse case scenario, they wreck it- it's already broke.

As I recall, also, there is only one tach adapter- for the V8 cars. The 4 and 6 cyl cars used the same tach, but used different pins on the connector. The tach adapter for the v8 cars was needed because Ford did not originally plan for a v8 in the II's.

 

[Wart]

I've always suspected the tach adapters of being poorly soldered.

And the plugs have always been a son of a b!+ch to pull from the adapter, and the adapter from the tach.

And cluster removal isn't made easier by the shortness of the lead from the harness to the cluster.

All this cussidness could lead to a physical break on the adapter board, or in one of it's componants. Or inside the tach.

The suggestion of taking the adapter to an old time radio repair is a good one, the new guys only know how to replace boards, not how to solder, or desolder, and check individual componants.