[Vwdiesel] no start, relay and a smoke puff

[James Hansen]

Comments below...

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?
___________

But this still points to a bad fuse panel or connections at the back.  Low
voltage in gives low voltage out. The 85 has the crappy high oxidation
factor plug in jacks on the back of the panel from each harness bundle.
Don't screw with anything until you have disconnected the battery, removed
the one screw holding in the fuse panel, pulled the panel and the mess of
wires away from the firewall, and had a good look at the back, and where all
the wire bundles plug into the back of the panel.  Pull each plug out of the
socket, and examine, clean if necessary with a good electrical contact
cleaner, and replace the plug. This is a known problem area, and is a source
of many burned cars.  The puff of smoke would have me wierded out after the
first occurrence.  Usually you let the smoke out of something, it does one
of two things- next time refuses to function, or lets out HUGE volumes of
smoke. Were I a betting man, I'd have 5 bucks on there being at least one
partially melted harness to fuse panel connection plug on the back of the
fuse panel. I'd suggest caution on using this car at all until you get it
sorted out.  I've had an electrical fire in a tractor, no fun at all. Cab
goes from clean air, to I can't see a thing nor breathe in under 2 seconds-
3 feet of vinyl wire turned red and cooked when it shorted out was all. No
fun.
___________________

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.
_____________

I still have my 68 fastback.  The ford starter solenoid was the fix for this
at the time- just a relay at the starter to get a full 12v to the starter to
pull the solenoid in. The wire from the battery, to the dash, through the
poor-ish fuse panel, the fair contacts in the ignition switch, and back to
the starter developed enough resistance in total, and only gave low current
to the solenoid. Still tested as 12.4 v with a meter under no load which is
what threw everyone, but was 9v with small load. Cold solenoid pulls in
easier than a hot one too, which makes it tougher to diagnose.  I had a 68
notch with this gremlin that kept coming back to the shop until I tested
voltage at the starter under load.
----
-James

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
>> >
>> >
>
>
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