OT: Car Intermittent Electrical Problem

 

Female friend, 1998 Pontiac Sunbird (or is that 1992?), 170K+ miles.

Starter motor operation has been intermittent twice.  In one case, she
couldn't get it to crank, so she found a ride to work and called someone to
service the vehicle the next day.  When they came to look at it, it started
right up for them (it had sat overnight).

I gave her a ride to work today because the starter wouldn't go.  Don't know
if it has failed for good now.

She tried all the obvious stuff, like wiggling the gear selector and trying
N instead of P.

Yesterday, her headlights went off at night and then came back on about 2
minutes later.  Ouch!

Questions:

a)In general, how does one diagnose an intermittent electrical problem?  Any
tricks?  I can just start guessing and replacing stuff until the behavior
stops, but maybe there is a less costly way or some science to it?

b)Any other suggestions?

c)Any place I can get a reliable vehicle electrical system schematic and
some basic service procedures (like how to disassemble and reassemble this
and that) without spending the big bucks and getting service documentation
from GM?

The word I don't like is "intermittent".  If it were just plain broke I
wouldn't mind.

Thanks, Datesfat

 


First, start with what some call normal maintenance.  Clean and tighten the
battery terminals, check the water in the battery, measure the voltage, etc.

Next, check the grounding cable from the battery to the engine, the positive
cables coming from the battery to the little boxes and gizmos, alternator
connection, check the fuze box and fuzes for corrosion, loose wires, shorts,
insects...

Not all of the above will directly affect the symptoms, but take very little
time, no money, and really should be done every decade or so.

Have the battery tested by a shop, unless you have a load tester handy.
This takes a little longer, but should still be free.


If the battery and electrical check it, it's probably time for a new
starter.  If you feel like shunting the connections on the starter solenoid
with a screwdriver, that should tell you quickly whether it's the starter or
something more hidden/sinister/horrible.  If you aren't sure how to do it,
don't.  Any halfway honest and not-completely-stupid mechanic will try this
some time before he even starts talking about replacing shit.  If he tries
to sell you stuff or service or even starts shaking his head before he's
done this, haul ass out of there!

A junkyard or Ebay find can be tested before anybody has to climb under the
car and get dirty.  A starter is pretty simple to install in most vehicles,
but I have had a GM truck where the damn transmission had to be pulled, so
your mileage may vary.  My basic rule is, if the old one can come out, the
new one can go in.

If it's not the starter, it's some place in between the starter and the
battery.  The only things that SHOULD be here is the ignition switch and
possibly a little box somewhere in the engine compartment.  After that many
miles, the ignition switch would be my guess, but that's a bit of a hassle
to find and replace, so check out that little box, if there is one.  There
shouldn't be anything complicated in there, just some terminals, possibly a
relay, and less possibly a fuze-y looking thingy that is, most likely, a
fuze.  Very little can go wrong in there, but the connections may be loose,
the relay may be bad, or something else obvious and easy and fairly cheap to
fix.  If there's a relay, it should, in most cases, click when the key is
turned on.  Also, the lights, guages, buzzers, and other doohickies that
annoy people when they turn the key should be merrily annoying away.

If it's the ignition switch, you'll want a book and access to tools before
attacking that.  Otherwise you'll need to find an honest mechanic.  Good
luck on that.


Chiltons manuals are good:

http://chilton.cengage.com/

These cover many different vehicles, and if memory serves they are a bit
pricey.

It's been years since I fiddled with cars.  It seems they have on-line
manuals now:

http://www.chiltondiy.com/default.aspx

Not a big fan of these.  I really don't want my laptop around greasy, heavy
tools.  Still, if you can print out the juicy parts, that would be Very
handy, and preferable to a regular book-type manual.

Finally, there are the vehicle specific manuals.  These are the ones you can
find in Pep Boys and various other auto stores.  They cost something like
$20 to $30, cover just about everything a non-pro-mechanic is capable of
working on, and are a mighty fine investment for folks driving older cars.


At least "intermittent" starter problems don't last very long.  Either they
fail completely within a few days or weeks, or they get fixed by mundane but
still important maintenance, like cleaning battery terminals.

CS

 

wrote:

It is my unpleasent duty to inject a human element to the auto
problems.
Is the lady one of those "fat chicks", and if so, do you feel that her
obesity
via overloading, etc,,is contributing to the problem?

climber

 

Turn on something you can monitor, like the headlights as long as you
can see if they're on while your'e under the hood. Move wires
*gently*. Watch the headlights.

The main thing to check is the battery terminal on the starter
solenoid. If there are fusible links coming off of that terminal,
the nut is probably loose.

Grounds might be a possibility, but I don't have the schematics
either.

On Sun, 4 Apr 2010 16:52:17 -0400, "Datesfat Chicks"

 



Intermittents are an absolute crying bastard to find, sometimes. Two
intermittents may or may not be related. In this instance, my suspicion
would fall on the main ignition switch, assuming that this needs to be
on for the headlights to work - and that varies from car to car. My
present Subaru, for examples, kills the lights when you turn the
ignition off, but my old Nissan didn't.

Why? Because if the ignition switch activates both headlights and
starter motor, and if they're both playing up, this is where I'd look
first. The switch, the fusebox, the connectors from the switch where it
plugs into theloom.


No idea.


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