[Vwdiesel] no start, relay and a smoke puff

[Tad]

so when it doesn't start, does it crank normally?

The starter grounds to the transmission body, and the battery connects
to the chassis via the ground cable, but what about the connection
between trans and chassis or battery?

The oil pressure sensor sounds like a bad ground problem too, but I
wouldn't swear they are related.

I'm not too up on IDI diesels but I'm guessing the wire from starter
to GP relay would be there to turn off the GPs while cranking?  But
4awg is way too big a wire.  Did you mean 14?

Erik's got a good point too.  On my old 78 I had a whole list of
bizarre intermittent problems that were eventually traced to a cracked
backplane on the fusebox.

One way to test my theory would be to put a voltmeter between the
starter ground (trans body) and battery negative terminal.  It should
read very close to zero(of course).  Repeat the test while cranking
the engine - it should still read very close to zero.  If it doesn't,
that means you've got a bad ground connection between the trans and
the battery - in other words resistance between the two, causing a
measurable difference in electrical potential when under load.

Of course I couldn't actually tell you what good or bad numbers would be... :)

On Wed, Mar 14, 2012 at 3:55 PM, Chris Jude <vegbenz300 at gmail.com> wrote:
> Tad,
>
> Thanks for the reply.  I'm looking at the wire-diagram (admittedly, I'm a
> little weak at electric diagram and DC troubleshooting),  it looks like the
> starter grounds through the transmission body, and the battery grounds at
> the ground cable, which looks ok  to me.  There is a 4awg wire goes from the
> starter to a pin on the glow plug relay.
> I've long had a funny problem on this car where the oil pressure buzzer goes
> off randomly, and is often (not always) shut off by beeping the horn.  But
> that may or may not be entirely unrelated.
> Any other suggestions on what to check with the ground path?
>
> Chris
>
>
> On Wed, Mar 14, 2012 at 5:23 PM, Tad <tadc at europa.com> wrote:
>>
>> Chris, I'd start with checking the ground path between the starter and
>> battery.  It sounds like you've got a bad connection that is
>> backfeeding current through whatever path is available (the TPS wire
>> in this case).  Not sure how the GP relay fits into the picture
>> though...
>>
>> On Wed, Mar 14, 2012 at 2:02 PM, Chris Jude <vegbenz300 at gmail.com> wrote:
>> > Folks,
>> >
>> > For the last couple weeks I've bee having an occasional no start
>> > situation
>> > with the 85 Jetta.  It's not every time, but occasionally the car wont
>> > start, and sometimes it won't start and there will be a small puff of
>> > smoke
>> > from the fuse box area.  I've noticed that the insulation of the Brown
>> > wire
>> > going to the throttle position sensor switch is melted.  When I remove
>> > the
>> > glow plug relay the car will crank and start fine (sans glow plugs).
>> > Last week, after this happened a couple days in a row, the battery died.
>> >  I
>> > tightened up a wire going to the alternator and that seemed to fix that
>> > problem, and the car started regularly for several days, no problems.
>> > Today the problem came back, with some smoke, I haven't looked yet to
>> > see
>> > if there is another fried wire.
>> > Any thoughts on where to look?  I don't see any bad connections at the
>> > fuse
>> > box, and the glow plug relay pins look fine.  The battery is charging as
>> > well.
>> >
>> > Thanks,
>> > Chris
>> > 1985 VW Jetta NA
>> > Pittsboro, NC
>> > _______________________________________________
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>> > Vwdiesel at vwfans.com
>> > http://www.audifans.com/mailman/listinfo/vwdiesel
>
>