Could I please have some confirmation that this
description is correct.
It was my understanding that the green wire was the "O2" signal and
other multi wire connection was the sensor heater power.
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>>> "Yurik Orlowsky" <
href="mailto:yuriko%40iinet.net.au">email@example.com> 11/23/09 3:25
The two plugs connect the O2 sensor (3 wire) and the single wire plug
wire) is the heater circuit for the O2 sensor. This wire supplies 12V
the ignition on. It would appear that the A/C people used this as a
source, with ignition on, for the compressor switch. A short here
upset the ECU in the starting mode and also the O2 sensor which
the idle misbehaviour. This is quite an elusive situation.
Glad it is sorted out.
On Behalf Of Les Harris
Sent: Monday, 23 November 2009 11:54 AM
Subject: RE: [Syncro_T3_Australia] VANAGON Electrical problem [1
[Attachment(s) from Les Harris included below]
I was about to post a report on this in any event but you have prompted
to do it now. I cannot objectively confirm the connection between the
symptoms and the fix, but here's what happened.
Sequence of events:
* Drove to Bunnings, about 10 k.
* Stopped in car park, idling very fast.
* Switched off engine.
* Came out about 15 minutes later, tried to start engine
* Very high cranking speed but would not fire
* After about 40 minutes, engine fired up, very rough but then
* Drove home 10 k, ran properly but high idle when I reached home.
* Found that the idle valve screw had no clearance, readjusted to
* Cold start was normal, idle was normal.
* Left Seabrook for Carrum Downs, where a group of Syncro owners
staying at a caravan park overnight.
* Drove down south east freeway, engine got lumpy when traffic
for road works
* Stalled at gate of the caravan park and had to be pushed in!
* Cold start was normal, idle was a bit lumpy.
* Drove to Cranbourne Racecourse (Day of the Volkswagen)
* Stalled as I was parking, would not restart.
* Tried restarting through the day when the engine was cold but
would not fire.
* Tried restarting at the end of the day but the engine would not
* Got a tow to get me out of the racecourse and the engine
* Drove to a servo in Cranbourne to get petrol
* Engine would start under tow but would not continue to run.
Note that I had on a previous occasion (several months ago) had the
cut out in the middle of a big roundabout at peak hour. Fortunately, I
a restart (a bit lumpy, but it started) and got away.
What Volkspower did was go through all of the signal values until they
a glitch in the ignition side. They traced it to a aftermarket wire
runs from a plug in the engine compartment to the pressure switch on
airco compressor. (I don't know what the function of this aftermarket
is in relation to the airco compressor.)
They found that there was a short in this wire that had thrown the
system. By the time the Syncro was flat topped to them, there was any
amount of cranking speed but no spark.
Simply removing this wire set everything back to normal. I have only
it a couple of times since, but everything appears to be running
The plug (see attached pic) is on the left side of the engine against
side wall of the engine compartment and is the lower of the two. It
be unplugged when the ignition is being is being reset. I haven't had
yet to read up this process in the manual yet but will do so.
I muttered something about !@#$%^&* aftermarket wiring to Dean and he
remarked drily "Yes, but it did take 20 years to fail." He has a
So there it is. A short in a wire fitted as part of the Prestige
installation was the culprit in this case. I cannot yet see the
between the most prominent initial symptom - the high idle - and the
shorting wire but this is not to say that it wasn't the cause. It
well have been creating a spurious signal to the ECU until it reached
stage where it would not fire at all.
On Behalf Of Nick
Sent: 23 November 2009 14:05
Subject: RE: [Syncro_T3_Australia] VANAGON Electrical problem
Could you please outline the cause of your electrical problem as you
briefly relayed that it was related to the aircon. I have been trying
trace a problem with my electrical system for the past 10 years and
not been able to resolve it. It may be similar as I have the same
after market aircon. Unfortunately as being located in Adelaide I am
not able to pop around to the same repairer.