Tachometer Issue

I recently purchased a 93 Mustang GT. The tachometer is at 0 when I turn the key on. After I start the engine, it is normal, at about 900 rpms, and after
5 seconds it moves up to 3500 rpms. It stays there unless I rev the engine past 3.5k or if i use my power windows, hazzards, A/C, etc. It jumps around erratically when turning pretty much anything electronic off or on.
Anyone know what might be going on here? I'd be greatfull for any help you could give.
Thanks, Moostang
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Moostang opined in

Not uncommon... there's a component failure in the tach.
About the only practical thing to do is get a cluster from the scrapyard, and swap out the tach assy.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.