Alternator Question

Wed Dec 12 04:34:16 PST 2007

Weird - this email was sent a few days ago. Please ignore...

Vittorio - 

-----Original Message-----
From: quattro-bounces at audifans.com [mailto:quattro-bounces at audifans.com]
On Behalf Of Vittorio Bares
Sent: Monday, December 10, 2007 4:01 PM
To: Andrew Duane; Quattro
Subject: RE: Alternator Question

Thanks - did that. Even replaced the spade lug as it had seen too many
RR cycles. 

The current test between the disconnected exciter wire and the
alternator (post 61 as its called in Bentley) should show 150ma - 180ma
- but mine spikes off the dial.

So that gets me ta thinking - is that what the exciter wire does? If the
current is low on that wire, charging goes to the battery and conversely
if its too high it does not charge (?). As is the case on my car?

Vittorio -

-----Original Message-----
From: quattro-bounces at audifans.com [mailto:quattro-bounces at audifans.com]
On Behalf Of Andrew Duane
Sent: Monday, December 10, 2007 3:54 PM
To: Quattro
Subject: RE: Alternator Question

I've never heard of the zener diode mentioned here, but the exciter
wires themselves are very prone to failure, especially on older cars.
Years of water and road salt and muck tend to eat them pretty quickly.

Take a look under the car, and find the small blue wire (the color may
be hard to see) that plugs into the alternator with a simple spade lug.
See if the connection is sturdy, the wire intact, etc. That simple test
(and replacing a wire or two) has saved me many "alternator repairs".

/Andrew

> -----Original Message-----
> From: quattro-bounces at audifans.com
[mailto:quattro-bounces at audifans.com]
> On Behalf Of Vittorio Bares
> Sent: Monday, December 10, 2007 3:42 PM
> To: Grant Lenahan
> Cc: Steve Sears; quattro at audifans.com; Mark R
> Subject: RE: Alternator Question
> 
> Thanks for all the information.
> 
> It would appear that the current test and resistance test on the
exciter
> wire failed. I've been told that there is a zenith diode on a circuit 
> board somewhere and that the circuit board needs to be changed out.
> 
> The question is - where is said circuit board? Is it in the dash or in

> the climate control box? Could this be exhibited as a gradual failure?
> 
> Thanks again!
> 
> 
> Vittorio -
> 
> 
> -----Original Message-----
> From: Grant Lenahan [mailto:glenahan at vfemail.net]
> Sent: Sunday, December 09, 2007 9:23 PM
> To: Grant Lenahan
> Cc: Vittorio Bares; quattro at audifans.com; Steve Sears; Mark R
> Subject: Re: Alternator Question
> 
> Wow, my typos were so bad you may have trouble interpreting.
> 
> I would first check ground - it is simpler ( and a common trouble 
> point).
> For this to be a common problem across various accessories it has to
be
> either in the common wiring or in the alternator/battery feed or
return,
> not an individual accessory's ground.
> 
> Next, if that fails, I would check B+.
> 
> Good luck, these are always annoying to track down,
> 
> Grant
> On Dec 9, 2007, at 9:15 PM, Grant Lenahan wrote:
> 
> > Sounds like a very high impedance system.  I'd check ground first,
B=
> > n ext (its more complicated).
> >
> > Grant
> > On Dec 9, 2007, at 5:28 PM, Vittorio Bares wrote:
> >
> >> More diagnosis:
> >>
> >> Leaving it at idle for a while seems to bring the (system) voltage 
> >> back to the point where the gauge shows 14v (volt meter never shows

> >> more than 14).
> >>
> >> Cooling fan, or headlights instantly bring the voltage down below 
> >> 12v.
> >> Smaller accessories such as dome lights, blower or dash lights
don't
> >> have much of an effect.
> >>
> >> Tried using booster cables to ground the radiator fan to the motor.
> >> No change.
> >>
> >> Engine revs have no effect on voltage once the system gets above 
> >> 12.5v.
> >> Took the car for a test run - went well enough for a while -
voltage
> >> dipped a little when fan came on - but not bad. Then I tried the 
> >> lights, ok for a short spell, then the fan came on and basically 
> >> killed the system. Charging well below 10v, car started running
badly
> 
> >> (not as much power, lightly missing) - looks like I was running on 
> >> battery only
> >> (?)
> >> and the extra juice from the lights on and the fan on sucked too
much
> 
> >> out of it.
> >>
> >> Made it back home - let it idle for a while, gradually the volt
meter
> 
> >> made it back into the normal range, around 14v.
> >>
> >> Right now, it would appear that the lights and the fan are running
an
> 
> >> unusually high load - what does that actually mean in practical
terms
> 
> >> - what am I looking for?
> >>
> >> TIA,
> >>
> >> Vittorio -
> >>
> >>
> >> -----Original Message-----
> >> From: Grant Lenahan [mailto:glenahan at vfemail.net]
> >> Sent: Sunday, December 09, 2007 2:50 PM
> >> To: Vittorio Bares
> >> Cc: Mark R; Steve Sears; quattro at audifans.com
> >> Subject: Re: Alternator Question
> >>
> >> I'm not sure where to start, and excuse me if you know all this,
but
> >> a few comments and questions come to mind:
> >>
> >> 1. You say it shows 12.5V running at idle.  It should be 14+V. This

> >> suggests the voltage is too low, preventing the regulator from 
> >> working.
> >>
> >> 2. You also say it is dropping when revving the motor. Is this 
> >> correct?
> >> Current - and thus ability to maintain voltage across any given
load
> >> - should rise with RPMs.  Yet it is falling. The only explanation I

> >> can think of is that the load is rising - faster than the rpms.  So

> >> what draws power more at high rpms?  Under normal operating 
> >> conditions, nothign I can think of.
> >>
> >> So this is a long-winded prep to "stop trying to fix the alternator

> >> and go find the unusually high load".
> >>
> >> Or, of course, find out if something is current limiting the 
> >> alternator, which might look similar.
> >>
> >> 3. If the diagnostic display now reads 12v - regardless of actual 
> >> voltage - it suggests that something is amiss in he dash cluster.
> >>
> >> 4. Could these be related? Or might the dash cluster simply be 
> >> inaccurate when working from a B+ voltage that is out of range. I 
> >> dont know, but I've seen that in the past. Way int he past.
> >>
> >> Good luck in your quest.
> >>
> >> Grant
> >> On Dec 9, 2007, at 2:25 PM, Vittorio Bares wrote:
> >>
> >>> Back at it - I've replaced the alternator w/a refurbished one - I 
> >>> now have 2 fully working units (tested at AutoZone) :\.
> >>>
> >>> Went back an cleaned contacts behind the snub nose (alternator 
> >>> bracket).
> >>> Cleaned contacts to adjustment bracket.
> >>>
> >>> Voltage is dropping when revving the motor.
> >>>
> >>> The diagnostic display for voltage on the climates control remains

> >>> at 12.0 (channel 11). This is regardless of what the needle on the

> >>> gauge is doing. It used to properly indicate the voltage.
> >>>
> >>> Needle shows just over 12v on idle. Verified w/volt meter.
> >>>
> >>> Voltage off of the alternator (+ post to engine ground) is about 
> >>> 12.5v
> >>
> >>> (seems low). I presume (it has a 14v regulator) it should read 14v

> >>> from somewhere - anyone know where to measure that from?
> >>>
> >>> Anyone know how to check continuity of exciter wire (blue) from 
> >>> alternator? Bentley says to check current across wire to
alternator
> >>> exciter post - I set my multi-meter to DC 250ma and the needle
shot
> >>> over max (?) Bentley says it should be between 150-180ma -
indicates
> 
> >>> if its low to replace climate control board - doesn't say anything

> >>> if its above ?
> >>>
> >>> Steve suggests in the attached thread to check voltage from the 
> >>> battery
> >>> - since the battery is charged via ground (I believe), would one
try
> 
> >>> to directly from one of the alternator mounting brackets to the 
> >>> negative post on the battery (a direct ground)?
> >>>
> >>> BTW - this is on a 1990 Audi 200 avant.
> >>>
> >>> Thanks!
> >>>
> >>> Vittorio -
> >>>
> >>>
> >>> -----Original Message-----
> >>> From: quattro-bounces at audifans.com [mailto:quattro- 
> >>> bounces at audifans.com] On Behalf Of Mark R
> >>> Sent: Monday, September 24, 2007 1:36 PM
> >>> To: Steve Sears
> >>> Cc: quattro at audifans.com
> >>> Subject: Re: Alternator Question
> >>>
> >>> Steve's got it right... often overlooked is the primary wiring.
> >>> Audi
> >>> didn't use the greatest wiring when new, and now you'll often find

> >>> corrosion under the sheath due to moisture wicking.  Remember, the

> >>> alternator has to have the ability to get the current (amperage)
out
> 
> >>> as well.
> >>>
> >>> Another quick and dirty test is to check voltage at the battery 
> >>> versus
> >>
> >>> the alternator post (if available when engine is running).  Set up

> >>> the
> >>
> >>> wiring before starting the engine.  If you see a voltage change 
> >>> (drop along the wiring), you'll need some attention there.
> >>>
> >>> Cheers!
> >>> Mark Rosenkrantz
> >>>
> >>>
> >>> On 9/24/07, Steve Sears <steve.sears at soil-mat.on.ca> wrote:
> >>>>
> >>>> Vittorio,
> >>>> If the alternator is one of those 110 amp units, then the two
bolt
> >>>> pivot is correct.  If it is the 90 amp unit, then it should have
a
> >>>> long bolt and nut at the pivot.  If you were to hook a long
jumper
> >>>> cable directly between the snubber mount to the battery ground, 
> >>>> would
> >>
> >>>> you get a different reading?
> >>>> (The engine ground to chassis across one of the engine mounts may

> >>>> be
> >>> bad).
> >>>> You might also check the condition of the battery cable splice.
> >>>> Cheers!
> >>>> Steve Sears
> >>>> 1962 and '64 Auto Union DKW Junior deLuxes 1980 Audi 5000
> >>>> 1987 Audi 5000 Turbo Quattro
> >>>>
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