Alternator + Battery + ...Tachometer? problems

McMkVIII94

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Could charging system and tach problems somehow be related? :confused:

About a month ago, I was driving my son to town and he says Hey, your tachs not working. It was "stuck" at just below 2k rpm.

We get to the school parking lot. I put it in Park and revved it a few times. The needle would jump to about where it should have been at correct engine rpm, but would not fall below the ~2k point at idle... then it just quit responding at all, still "stuck" at the same place.

After that, the car stayed parked for over 3 weeks without being started. I went out to go for a ride last Sat. morning and the less-than-6 months-old battery was dead... very dead. I trickle charged it for a couple of days, cranked the car and the dash panel battery light was on. Tested it at the battery posts with a digital multi-meter, with the car running, and got just over 12v. The 20a ALT fuse in the engine bay box is fine. Yesterday traded the Reilly's Super Start battery (it had a dead cell) for a new Motorcraft 850, same voltage reading while running.

Daaayum!!!... now I got a dead alternator too!?!?

Up until the tach quit, everything was fine... no battery light, no CEL, no nothing... any ideas or suggestions?

p.s. I've searched all the alternator threads here, checked prices online for new and reman'd, then called a reputable local auto elec. shop. They have a Gen II reman ready to go for $110 (with my core) with a one year warranty.

Unless I can find something better (cheaper), I'll take mine to them for testing and buy theirs if it's bad.

But what, if anything, does all this have to do the tach?!?!... or was it "just coincidence" that the tach and alternator died at the same time?
 
Gen I tachs are known to go bad but they can be replaced fairly easily.

I would replace the alternator and then see what happens. If the tach is still sticking (common) replace it with a known good one.
Someone here might even have one for sale.
 
+1 on dead tach. unrelated. happened on my car. happened on our xr7. the tach's just get stuck or something.

3 weeks is a long time for a battery to set. new or not.

charging just over 12 volts isnt enough. sounds like you lost an alternator. could be brushes or voltage regulator. cheap parts, but hard to replace on a gen 1 alt.
if you get a new alt, get a gen 2. better design.

and be prepared to warranty a reman. most remans just totally suck right out of the box. i would even make them bench test it before you take it home.
 
A belated "thanks" for the responses guys. Been a busy week for me, and had to go out of town this weekend, so I haven't done anything else to fix my alt. issue.

In the OP, I was just "fishin' "... to see if there was a known connection between the two problems that I couldn't find using the search.

Maybe I can get to Columbus some time this week and get the reman'd alt., it's a Gen II.
 
dont replace the tach just yet. its a pretty easy fix its common that the gages will slip down and stick the needle. there is actually faqs out there on how to correct it. i dont have a link at the momont but the just of it is to reglue it back into place. I had to do the same to my tach and its been working great ever since
 
dont replace the tach just yet. its a pretty easy fix its common that the gages will slip down and stick the needle. there is actually faqs out there on how to correct it. i dont have a link at the momont but the just of it is to reglue it back into place. I had to do the same to my tach and its been working great ever since

Thanks for that...

I'm pretty well convinced it was one too many WOTs that killed the alt. (but I LOVE IT!)... nice to know the tach ~may~ be fixable... will get on that once the alt. is done.
 
Thanks for that...

I'm pretty well convinced it was one too many WOTs that killed the alt. (but I LOVE IT!)... nice to know the tach ~may~ be fixable... will get on that once the alt. is done.


if its an autozone alt. then yes WOT will do that. ive gone through so many that autozone was like wtf. i said life time warranty. you set the policy i just use it. make better parts and ya wont see me every few weeks.
 

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