Re: A/C Fault code #9

[Eric Maxon <emaxon@megsinet.net>]

SSpangenbe@aol.com wrote:

> Also, the volts shown on channel 11 fluctuate from 12.1 to 13.6 as I'm
> driving.  No changes to the load put on the alternator.  Is this normal or
> should I get a new voltage regulator?
> 
> tia,
> 
> Scott
> 
> 89 200T, 188k mi
> 85 5ks, gone
> 79 5ks, gone

I've had several customers come in with aleged alternator problems that
turned out to be a bad connection in the field coil wire to the
alternator--(blue 20ga wire near the washer bottle in the right front of
the engine compartment-- one single clear plastic connector is usually
cable tied to the body.  Follow the wire away from the alternator to
find it.) 

Has the "BAT" light ever stayed lit once you've started the engine?  It
should light before you start the engine, then immediately shut off once
the engine's running-- the light indicates current draw throught the
field coil circuit which is necessary to "prime" the alternator.  Until
the field coil is energized, the alt won't generate power.  Once it
begins to generate power, it powers its field coil so current draw
through the aforementioned field coil wire drops to zero and no more
light.  

Once the alternator is going, integrity of the blue wire is not an
issue, so if the voltage drops only when *driving* there may indeed be a
problem with the Vreg/brush block in the alternator (worn out brushes--
should be at least 5mm long at deepest wear spot.)

It's natural for voltage to drop a bit under heavy load (cooling fan,
heater/ac blower, headlights, etc. on) but dropping to 12.1V is not cool
(less than the resting voltage of a fully charged battery so you'll
never get a full charge with this charging voltage.)  

The Vreg/Brush block shouldn't cost you more than $30 from an
alternator/starter rebuild shop and you can replace it with minimal
tools-- you don't even have to remove the alternator.

Good luck.

Eric.
-- 
The Manicured Mechanic's time & $$$ go here...
'86 5kcs, '85 4ksq, '84 4ks, (insert '83 Urq here... please:)
dust & bird droppings collect here...
'82 4ks, '81 Tercel SR5, '80 Scirocco