re. Load reduction relay x-track '84 cgt

[Ben Swann]

On Friday, August 02, 2002 12:27 PM, Graham Thackrah
[SMTP:gthack at geog.ucl.ac.uk] wrote:
> Hi Ben, Sean, Mike,
>
> > I looked at the wiring diagram for the early '84 Coupe with Sean as his
car
> > is #9 in my driveway.
>
> heh, now, that's what I call a driveway;)

It' amazing what you can squeeze in here - and the neighbors don't even
know.
>
> > Anyway,  X or Load reduction relay as far as I can tell only carries
> > ancillary equipment like wipers, defrost, and nothing to do with the
> > engine.

And does not carry  the load for the cooling fan.  That takes current
directly off of current track 30 and therefor is hot(+) even when car is
off..though you bring up a good point - it may be drawing the battery down
significantly.  I dont even see a fuse for it in the diagram, but it does
seem to cycle properly when engine warmed up and doesn't seem to be acting
unusual.
>
> that's what I thought, you wouldn't want an engine related component
being
> switched off when trying to start the car
>
> > What we have observed with the engine running, is that it appears to
cutout
> > after the fan starts cycling.  It appears to be electrical.

Also when we were testing, the load reduction relay was removed.  Most of
the relays we deemed not critical for engine operation were removed as
well, just to try and narrow things down.
> >
> > For some reason even after changing voltage reg. and or alternator
several
> > times, their is no charging.  We observe that the voltage diminishes
> > somewhat over time, although I don't beleive this is causing the engine
to
> > cut-out, as I have an '85 coupe that runs happily for an hour without
an
> > alternator belt.
>
> If it's not charging then that drop in voltage is the battery draining?
If
> so, and if you've not got anything else switched on (apart from the rad
> fan...) then you could have a short somewhere, I drove for a good 3/4 hr
> once with no alt belt, watched the voltmeter drop every time I put the
> brakes on:( But if your fan starts cutting in, I would imagine that
drains
> the battery fairly quickly? I was driving in cool conditions (in daylight
> too) so it never came on - I just got nervous in traffic.

I don't think the fans draws enough to bring the battery down sufficiently
that the engine dies.  The starter draws way more.  It is like the car gets
up to op temp, fan cycles twice and then it misses and begins to run rough,
then cuts out.
>
> I may have missed something somewhere too, didn't you say the x relay
> switched components weren't working,
 Maybe - Sean?  I think he thought so, but found some blown fuses.

 the rad fan is on the load reduction
> circuit (or it was on my UK '85 90q - US 4kq) so how have you got power
to
> it?

No - According to Bentley, Rad fan has a separate relay controlled by
thermo switch in radiator, and has no fuse.

>
> > The cheater wire appears to me to be a bastard cludge, and has no
business
> > in the car.  If an additional power wire or ground needs to be run,
there
> > is a proper way to do this.  The wire eminated from one of the empty
relay
> > slots - like unused cab or police, which would have been ok, except
that it
> > then goes up and out through the engine compartment and kind of wraps
> > around the car on down all the way to the pump - pretty sloppy.  Based
on
> > your comment below, you imply that the existing fuel pump wiring is
> > inadequate to run the pump and CIS control.  I guess we can look at
that.
>
> Would marginal wiring to the fp actually stall the car though? I'd have
> thought that it would get enough volts to at least let it idle, even if
> the rad fan was on? It usually supplies more than enough fuel for the
> needs of the engine, so there's a large margin there.

This is something we should not rule out.  I've had cars before, mostly
older VW's that ran fine, but would cut-out intermittantly for months
making the problem hard to diagnose until finally the pump would die
altogether.  The pumps typically died in either very hot weather, or
ironically, very cold (ice?).

The car sitting right next to Sean's '84 coupe is an '84 4kq and same color
red (twins?) except this has CIS-E(late '84).  It started and ran fine a
few weeks ago.  We went to start it so I could clean the lot and after some
trouble shooting found the fuel pump to be putting a serious draw.  I
figure I need to drain the tank as it may be clogged with varnish.  Anyway,
so Seans's may very well be fuel pump acting up when getting hot.

>
> > We tried substituting an ignition swicth - still cuts out.
>
> bah, never mind, worth a try
>
> > I am beginning to suspect there may be some harness meltdown going on.
> >  Sean has been methodiacally isolating the problem however.
>
> If I recall then you have, no charging from the alt.

Seems that way - sean is taking the alts in for testing..he has three to
try.  At least we can rule these in or out.

>  a faulty load reduction circuit and the car will stop running after the
fan starts
> cycling, is that a fair summary of the problem(s)?  No, as above fan does
not relate to lr/X circuit..may or may no be a problem.

> Or is the lr circuit one fixed?

Well See.
>
> > Anyway, any hints or tips about wiring deficiencies in this particular
> > model would be helpful.
Sean did run a ground (10/12 Guage?) from Alt. to block to battery I think,
in hopes that would help.  I'm sure it does, but is not the underlying
problem.

Observations over the last few days have shown, that these cars (mid '80's
4000 coupes and quattros are fickle) about grounds.  In particular, there
is a ground wire running from neg(-) battery to the bellhousing bolt which
will cause at the very least hard cranking if not in good order.
>
> Thought about a whole new loom;)?

BTDT - not fun, but will do if necessary.  I thought I'd stop seeing these
sorts of problems when I stopped fooling with VW's and switched to AUDI.
 Yeah, right!

> Cheerio,
>
> Graham.

Later..Ben