They are the mounting tabs for the dash/cluster that screw go in to mount to the cluster to the dash frame, they are clean though, yeah noticed after removing and replacing cluster to install the mini tach but like I said checked with the mini tach disconnected and still happens. Was happening prior to replacing regulator and alternator, did so trying to rule out source of problem. It has a complete new under hood wiring harness so not the problem there either.

 

just went through it all.....low rpm's and such will cause along with all of the above,,bought a new volt regulator from checkes/parts america came with a "what is this:" under the "NORMAL REGULATER" which looked like the orignial,, reginal,,,,,and low and behold end of issue,,,bottom line for me is... there is a difference in volt reg's

new alt, main harness,,need new rear and front wiring harness, gauges, new 5 volt reg for gauges etc

 

AAhhh - good..

 

mine was rock solid,,go into some electrical garbadge replaced volt reg ulator,, staid the same 2 years later checked my records ( bought a ton from autozone)and bought the original from checkers,,,,went back bought another from them and lo and behold there was a funky resister? and rasied base on it and once again everything is cool,,,don't know what that resister? is but it 's all good now

 

Hi Guys:
I have a 1990 Mustang GT ragtop and am experiencing the fluctuating ammeter problem.
Have replaced the battery and the alternator and yesterday had new voltage rectifier replaced, still under guarantee.

Yesterday, the red battery light came on while driving which really freaked me out.

Reading the posts, it seems I have a bad ground somewhere, or maybe a new rectifier is needed.


I guess it will have to go to an autoelectrician.

The ammmeter fluctuates at drive RPM, not at idle. It will stay stable and then with no change in speed or switching anything on, start drooping, then pick up again.

 

The alternator belt may not be very tight. I had one the seemed tight but wouldn't charge my battery. I tightened it up after checking that the other components weren't what was wrong with my car. Good Luck.
Also, after it is tightened it still won't be 100% stable!

 

Two things regarding alternators: be sure not to OVERtighten your belt as well. Alternators from generic parts stores have a high likelyhood of living short lives. There is a reason they offer (and can afford to!) lifetime warranties on them.