Re: [xj-s] Alternator repaired/more on "extra" connector

[sean.straw+Jaguar@mail.professional.org (Sean Straw)]

At 09:57 15-07-98 -0500, Jim Isbell wrote:

[snip - got it rebuilt for US$100]

So, what was the added cost of replacing the bearings?

>I had a further conversation with them about the "extra"  blade connector.
>They still call it an "IGNITOR" connection and they say some ignition
>systems need it.  They confirm my analysis that the screw stud IS the field
>exciter connection from the meter and the two large blade connectors ARE
>the output terminals.

I'm looking at the parts guide right now, and the 75A Lucas alternator (for
engines < 8S57572 - a Bosch 115A superceedes it after then).  The various
replacement parts listed are:

	JML 277	Regulator (internally mounted)
	JLM 278	Rectifier (diode bridge)
	JLM 9555	Brush set
	AEU 1616J	Capacitor (externally mounted, has a green wire)

On my '88, I've measured resistance between the battery post and frame
ground (three points - a tiny unpainted exposure on the fuel tank, the
ground strap itself (at frame), and one of the ECU mounting/ground bolts -
I get .9-1.0 ohm resistance (might need to do a scrub on the post or
something, but overall, this seems fairly trivial resistance).  I did a
similar test (using the jumpers below) from the alternator frame to the
ground post on the battery, and get a similarily low reading.  BTW, my
(digital RMS) metre shows 0 ohms on shorting the test leads, so I'm
reasonably sure there isn't any reading error introduced by the leads
themselves.

Then I clipped two of my test jumpers (alligator clips at either end of
both) together and measured resistance across them.  1 ohm end-to-end (old
for-crap speaker wire probably - when I'd made them, I didn't expect to use
them for anything more precise than bridging relay switch currents).  I
clipped one to the + lead terminal in the engine compartment (passenger
side one - the same one the starter soleniod channels juice from), clipped
the other end to the metre, and measured resistance through to the positive
terminal on the battery.  1.4 ohms.  Sufficiently similar to the ground
circuit (and, with the 1 ohm resistance of the test lead itself, that
corrects to .4 ohms).

I haven't yet jacked the Cat up to get at the posts on the back of the
alternator, but the next test will be measuring the resistance between the
alternator output and the forward + post.  This should confirm that the
leads between the battery and alternator all have good continuity, and that
ground is good.

(Speaking of ground, where would I find the engine block grounding strap?
There IS one, isn't there?)

p86-07 of my edition of the XJS Service Manual (Volume 4, Jaguar part No
JJM 10 04 06), has diagnostics for testing the alternator.  I've
temporarily replicated these pages on my site if anyone is interested in
seeing the procedures.

	<http://jaguar.professional.org/XJSServiceManual/LucasAlternator.html>

	When prompted, the username is "July98" and the password is "Lyons"


Anyway, in looking at the diagrams of the (Lucas A133) alternator, I don't
see any other connections which aren't clearly shorted with an existing
connection.  Could you give me some idea as to where this ignitor/exciter
connector is?

I note that there is a surge protection diode INSIDE the alternator.  This
appears to be a replaceable component (the diagnostics include mention of
it as a cause of failure for one of the tests - #4), but there is no
replacement part number listed (even in the parts guide).  Does anybody
have a reference part number - I'd like to add a note to my parts guide as
well as know if I have to replace it that I'll be able to find it.

---                             <http://jaguar.professional.org/>
Sean Straw                      '88 Jaguar XJSC 5.3L V12
Marin County, California        '69 Buick GranSport 455 V8

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Follow-Ups:

• Re: [xj-s] Alternator repaired/more on "extra" connector
• From: Mike Morrin <mikem@southern.co.nz>

References:

• [xj-s] Alternator repaired/more on "extra" connector
• From: Jim Isbell <jisbelljr@mail.utexas.edu>

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