[Vwdiesel] no start, relay and a smoke puff

[Tad]

Yeah the list has been quiet lately.  Good times for diesels I guess. :)

Okay, so if the car doesn't crank at all... lets assume it's because
the starter solenoid isn't getting enough voltage to switch.  You pull
the GP relay, and now it does get enough.

And it always cranks normally with the GP relay out?

And the dead battery...

I wonder if the GP relay is sticking "on" sometimes, pulling enough
power to prevent the starter solenoid from switching on?

Reminds me of my sister's old 68 fastback.  Started fine most of the
time, but once in a while (usually after a long drive, like stopping
for gas on a road trip) it just wouldn't crank.  Unfortunately an
automatic, so no push-starting.

Sometimes a jump-start would do the trick, but waiting long enough
(usually hours) always would.

She had it in several mechanics/VW dealers between Oregon and Georgia,
and they did lots of parts-changing, but nobody ever fixed it.  She
eventually unloaded it on some poor sucker college kid from OSU (the
car was OSU Beaver Orange).

On Wed, Mar 14, 2012 at 5:48 PM, Chris Jude <vegbenz300 at gmail.com> wrote:
> Yeah, it either doesn't crank at all, or it cranks just fine.  I believe
> that there is a ground strap from the trans to the the chassis that the
> battery is grounded to as well.
> I've read and reread the legend for the Bentley manual wiring diagrams, and
> it says the number listed with the wire color code is the AWG.  Doesn't seem
> right though, as many of the wires are list as .5 or 15.  For instance the
> code for the glow plug wire is 6.0 R/W
> I must be reading it incorrectly.
>
> Chris
>
> ps- has the list been really really quiet, or is this the only active thread
> right now?
>
>
> On Wed, Mar 14, 2012 at 8:23 PM, Tad <tadc at europa.com> wrote:
>>
>> 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
>> >> > _______________________________________________
>> >> > Vwdiesel mailing list
>> >> > Vwdiesel at vwfans.com
>> >> > http://www.audifans.com/mailman/listinfo/vwdiesel
>> >
>> >
>
>