[Vwdiesel] Fwd: no start, relay and a smoke puff

Thu Mar 15 22:23:42 PDT 2012

---------- Forwarded message ----------
From: Chris Jude <vegbenz300 at gmail.com>
Date: Thu, Mar 15, 2012 at 7:04 PM
Subject: Re: [Vwdiesel] no start, relay and a smoke puff
To: Tad <tadc at europa.com>

Yes, it does seem to always crank fine with the GP relay out.  It also
very often cranks normally with it in!
I really don't want to drive this car at all until I can track and
correct the problem, but i still have to get to work everyday so I
need a good weekend of ground chasing.  I'm a little shaky on testing
circuits, but I just need to get my electrical tester and test either
for continuity or voltage I guess.
I cut the burnt wire out and taped up it's ends, which I know is not
the right fix, but I wanted to get the bare wire out of the wire
bundles for the immediate future.   I've already bought a 2000 Jetta
TDI, but I'm waiting for the seller, a friend, to finish a manual
tranny swap before I take ownership.  I just need the 85 to make it
another week or two before I can pull her off duty and really go over
the car correctly.

Chris

On Wed, Mar 14, 2012 at 9:15 PM, Tad <tadc at europa.com> wrote:
>
> 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
> >> >
> >> >
> >
> >