I am suffering from what I understand to be a standard lbc problem--the battery
drains
overnight. Manual suggests (among other things) a short in lighting circuit.
Another
suspect (imo) is a short in the alternator. I haven't been able to locate a
short in the
lighting circuit (or anywhere else) yet, so I'm asking for helpful suggestions,
ie.:
Who are the usual suspects in the lighting circuit, what handy detective tricks
can I use
to locate the problem?...
With respect to my suspicions about the alternator, a charging check at Western
Auto
indicated proper charging. I am suspicious of a leak within the alternator,
though,
because I noticed when charging the battery (6 amp charger) the alternator was
noticably
warm. Is this normal? Does this symptom indicate a short to ground within the
alternator?
There are two hot (unswitched) brown wires connected to alternator. No
measurable voltage
on any terminal of the starter solenoid except the hot ones.
Are there other potential problems other than the lighting circuits? I assume
any
energized circuit (or any conductor on the hot side of any switch) is a
candidate. I
think I saw (in the circuit diagram) some diodes in the circuit serving the
brake hydraulic
pressure sensor--what happens if those fail?
As "recent" work is logical likely cause of the unidentified problem, you
should know it
includes recent replacement of engine after rebuild, (all electrical
connections), and
addition of an electrically lighted (but otherwise mechanical) bourdon tube oil
pressure
gage. I have disconnected the lamp in that gage to help locate problem. Don't
yet know
results of that attempt, but I don't think that is the problem. Maybe a new
lamp or two in
license plate light and reversing lamps, etc. Battery is new (replaced the
one my son
assassinated by welding wrench across terminals--I don't see how this could
damage other
components, though)
I spent a few minutes last night with a voltmeter trying to define the problem.
I did
connect voltmeter from battery (-) to chassis (with negative battery lead
disconnected at
battery) and found battery(-) to chassis potential was approx 11.75v. This
indicates short
to ground from some energized circuit (right?). I tried removing each fuse in
turn, and
noted no change in the observed potential. This indicates short is on hot side
of fuse box
(right?). Seems like I also tried removing hot connections to alternator while
watching
this potential, but can't recall learning anything. I'll repeat this test more
methodically later.
Many thanks in advance for any suggestions--you can e-mail me direct or I'll
read the
digest; I stay a few days behind, though.
-------------------------------------
Name: Ray W. James
Texas Transportation Institute
Civil Engineering Department, Texas A&M University
E-mail: Ray James <rwj4123@sigma.tamu.edu>
Date: 09/21/94
Time: 09:17:52
-------------------------------------
|