[Vwdiesel] Rabbit electrical problem

Roger Brown r.c.brown at ieee.org
Thu Apr 7 11:23:50 EDT 2005

Mark LaPlante wrote:
> Questions:
> What is likely to be causing the buzzing/clicking? A relay without
> enough juice to engage? Is that a normal symptom of a low battery, or is
> it a clue to what is faulty?

Yes, common thing.  Most relays need about 1/2 normal voltage to pull in.  If the voltage is at that threshold or there is a bad
connection limiting current, the relay can buzz/click like that, in fact they always click.  The reason you hear it now is that
since it is not turning on all the way, whatevey "noisy" thing it used to turn on that masked the click of the relay is not
being turned on and thus you hear the click.  If you tear apart an electro-magnetic buzzer it is basically a relay, has a coil
and a contact that it pulled open by the magnetic field.  Contact is wired in series with the coil.  Current flow, coil opens
contact, current stops, contact closes.  Repeat this fast enough and you have a buzzer.

> I know water can leak from the windshield into the relays. But, if that
> were the problem, wouldn't I have problems starting even with a booster
> battery attached? I have not noticed any water on the floor, but I will
> check under the dash in the morning for moisture.
> I feel it is more likely that something is draining my battery or it is
> not being recharged properly. I have not noticed any glow of the charge
> light, but I have for some time had a small squeaking noise at idle that
> goes away with any throttle at all. All the belts seemed tight.
> As an aside, I think I have at least one glow plug that is not working.
> I get a cloud of white smoke at startup and lopey running for several
> seconds. The colder it is the larger the cloud. If I go ahead and pull
> away, the smoking stops.
> OK, I'm sure there are clues in there somewhere. Please ask any
> questions I should seek to answer.

For charging, make sure the running voltage is 13.8V or higher when you blip the throttle up over 2500RPM after starting.  If it
does not jump up that high, the alt. is not charging the battery.

For a finer test than Loren's test light, hook up an ammeter (10A scale to start with) in series with the battery (power or
ground works the same) and note the current flowing with nothing turned on.  If the current is more than about 20-50 mA
(0.020-0.050 amps) start pulling fuses/relays/etc. until it drops.  The last thing you pulled out is on the circuit with the
short or high load.  


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