[V8] Tach drop out

[Ingo Rautenberg]

Possibly.  But in my experience, the tach is the only gauge I've seen in
these cars that actually "goes bad." ..and the only one I've had to replace.
I still have the bad one from mom's first V8 if anyone wants to experiment
with it : )

Best of luck,

Ingo
----- Original Message ----- 
From: <dsaad at icehouse.net>
To: <v8 at audifans.com>
Sent: Friday, August 25, 2006 10:25 AM
Subject: Re: [V8] Tach drop out


> This smells like a connection problem in the IC to me.
> I don't have the schematics in front of me, but if you have the schematics
and
> can follow them, and can use a volt meter, you should be able to locate
the
> problem.
>
> First, locate the signal source. This is almost certainly the ECU, and it
is
> probably a pulsing signal - so it will be hard to measure with an ordinary
meter
> but if yours can read frequency then you are good. The tach is responsible
for
> turning this pulse into a voltage for display - the tach is really just a
volt
> meter, as is the speedo. They both work the same way, only the frequency
of the
> signal is different.
>
> (btw, I went through this same procedure to identify my bad speedo sensor)
>
> You will need to attach your meter to the signal at the ECU and monitor it
while
> driving, or do whatever needs to be done to make it fail. If the signal
drops
> out then you have an ECU problem. (I really doubt this - it is just the
first
> step)
> If everything is OK, it is time to pull apart the IC and attach the meter
right
> at the tach terminal - you may need to solder here. If the signal drops
out, you
> have a connection problem. If not you still have to verify the 12V and
ground
> supply to the tach but most likely there is a broken wire or intermittant
> connection. I found the interconnect wires between the IC sections were
cracked
> on mine. There is a design weekness (IMHO) where the interconnect ribbon
cables
> can vibrate and crack over time.
>
>
> Dave
>
>
> Quoting Mike Del Tergo <mdeltergo at hotmail.com>:
>
> > That will keep you busy. On the tach I don't know if it is the IC as I
have
> > "fixed" that.  Suddenly, it will go to zero (or not come on) and stay
there
> > only coming on intermittantly.  Others have said these can go bad, but
no
> > one seems to have a way to check if it is the tach or wiring.
> > Mike
> > PS had to go to a wrench to get the O2 off but all seems good now.
> >
> > >  Mike sorry I haven't gotten back but I was doing my
> > >T-belt on my Green 93 v8 & the Euros, & the 2benn coil
> > >overs & stuff ready for //sfest. I'm just doing a few
> > >more things beforhand but I will check to see if I
> > >have a tach. Whats wrong with the tach?? I all so have
> > >to search around for the armrest strut.
> > >I'll get back to you tomorrow
> > >Thanx
> > >Ron
> > >
> >
> >
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