Rev Counter/alternator

I have a RRC 3.9 '91 Auto and replaced the alternator about 6 months ago
with a recon unit.

Just over the past few days the charge warning light is taking longer to go
out after starting each time and the rev counter has started substantially
under reading, I know the rev counter gets it signal from the alternator.

I have checked the charge from the alternator and when the ignition warning
light is extinguished, the charge is good and I have no starting issues.

Is there a way of checking whether the rev counter fault is with the
alternator or with the rev counter?

AlunP

Alun P wrote:

> I have a RRC 3.9 '91 Auto and replaced the alternator about 6 months
> ago with a recon unit.
>
> Just over the past few days the charge warning light is taking longer
> to go out after starting each time and the rev counter has started
> substantially under reading, I know the rev counter gets it signal
> from the alternator.
>
> I have checked the charge from the alternator and when the ignition
> warning light is extinguished, the charge is good and I have no
> starting issues.
>
> Is there a way of checking whether the rev counter fault is with the
> alternator or with the rev counter?

Check the tension of the fan-belt - just in case!

Alun P wrote:
> I have a RRC 3.9 '91 Auto and replaced the alternator about 6 months ago
> with a recon unit.
>
> Just over the past few days the charge warning light is taking longer to
> go out after starting each time and the rev counter has started
> substantially under reading, I know the rev counter gets it signal from
> the alternator.

Gut feel (and educated guess) is that one set of windings have gone open
circuit. Your 2 options are to take it off and get it checked (or check
it yourself if you've got the knowledge), or fire it on a scope and see
what the HF ripple looks like (I'll bet there's only 2 traces showing).

--
EMB