More Bringing up a CPM

From: Dwight Elvey <elvey_at_hal.com>
Date: Wed Jun 2 14:11:34 1999

Jim Strickland <jim_at_calico.litterbox.com> wrote:
> > 1. Observe symptoms
> > 2. Make predictions
> > 3. validate predictions
> > 4. If predictions do not pan out add this
> > to the observed symptoms and go back to step 2 or 1.
> > 5. Repair bad part.
> >
> > I find that most don't understand the importance of steps
> > 2 and 3. They try to go from 1 to 5 and usually it doesn't
> > work. Step 2 does require that you understand what to
> > expect from each kind of failure.
> > Dwight
> >
> I think I've mentioned this before, but the best discussion of
> troubleshooting
> methodology I've seen is to be found in "How to Keep Your Volkswagon Alive
> -
> a Manual of Step by Step Instructions for the Compleat (sic) Idiot." by
> John Muir in the section marked "Volkswagon won't start." It's not
> electronic
> trouble shooting, but the method is the same.

Hi Jim
 It is still important for autos. Most parts stores have
a "no return on electrical parts" policy. Just because
the battery isn't charging, doesn't mean that the
alternator is bad. You need to look at wiring, ignition switch
and regulator as well.
 For the home auto repair, a few tips. Most alternators that
fail from old age, fail because of worn out brushes.
These can be replaced for $1.5 to $3 and a few minutes
of time.
 Second hint on alternators. Ask if someone jump started
another car within the last month. If so, it is most likely
the diodes. This is a hold over from the generator days
when you couldn't damage a generator with momentary overloads.
The diodes in autos are slow reacting. This means that a
high voltage pulse, such as comes from a starter opening,
can cause a high reverse current flow. This will almost
always blow the diodes. The rule is, turn off the charging
cars engine before attempting to start dead battery cars
engine ( after giving the dead car at least 5 mins of charge ).
Dwight
Sorry about the OT, I could help my self.
Received on Wed Jun 02 1999 - 14:11:34 BST

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