[urq] Re: No Start[spark or fuelpump] condition with no codes on MC-1 CGT conversion

Ben Swann benswann at comcast.net
Fri Oct 1 10:14:44 EDT 2004

This is a single reply to multiple replies to my original post.  Although I
seem to find these solutions on my own mostly, I'm sure it is the responses
from the audifans collective that help focus me onto the solution.  I seem
to be getting closer, but have not nailed down a solution.  I have no
question that I am getting 12 V to the coil 15 during cranking, but question
as to whether I am getting a primary signal on terminal 1 of the coil.  The
late reply from Tony H. I think alludes to the culprit as I describe below.

FWIW, I believe I am looking at the problem, but not seeing the exact
culprit, or at least how to resolve it.  I have things wired according to
the Bentley diagram for 5kt's, except, something seems to be missing with
respect to the connection(s) that go to coil terminal 1.

Looking at the diagram, it shows ***only the green wire that goes from the
Idle Stabilizer Valve Control Unit(ISVCU) terminal 17/1 is connected to Coil
terminal 1***.  The other segment on ISVCU 17/1 is shown to go to the
autocheck controller.  Therefore, the diagram does not show a control signal
feed that comes directly from the ECU that aught to go to the coil terminal
1.  So it a appears the problem is I am missing this feed, or it is not
being enabled or passed through ISVCU or other means.  Is ICU that Tony
refers to the same as what I am Calling the ISVCU?

Where the wiring for this installation begins to not follow the diagram
exactly is with repect to other control leads that go into the ISVCU.  For
example, I have no afterrun relay in place, as the afterrun pump and are not
installed yet, if I'll even do it this way.  So the R/W wire off ISVCU/6/KA
going to 14b/9 is not connected to anything.  Other wires for AC control
(ISVCU/2/K - talk about convoluted) are not connected yet, either.  The
ISVCU 5/31 should have a return to ground through the MAC-11 harness, but I
can double-check.  I am pretty sure I checked that the ISVCU 14/15 is wired
to ign track 15 +.  Much of the wiring for the ISV CU is already there as
internal to the MAC-11 harness, so I took it for granted that these things
should operate as a collective entity with no outside control required.

So, which ECU connection is used to provide the signal that should go to
terminal 1 on the ignition coil?  I don't see how it gets there with the
factory wiring, but it somehow must get passed through the ISV control unit.
That would mean the engine on a 5kt will not run with the ISVCU pulled?

Looks like I need to find which wire on the ECU or how to get the ISVCU
wired so it passes the appropriate signal.  If anyone has an idea, LMK



p.s. remember when firing an engine with points and coil on a test stand was
so easy - hook up positive wire to coil and starter and ground the block -
something like 2-3 wires max.

----- Original Message(s) -----  **** note consolidated posts with a single
reply ****
From: "Michael Sylvester" <msylvester at verizon.net> and "Jim Green"
<jim.green at gmail.com> and
"Hoffman Anthony J A1C 552 CMS/MXMVC" <Anthony.Hoffman at tinker.af.mil> and
"Justin Riley" jriley at ctiusa.com
To: "Ben Swann" <benswann at comcast.net>
Sent: Thursday, September 30, 2004 10:42 PM
Subject: Re: [urq] Re: No Start[spark or fuelpump] condition with no codes
on MC-1 CGT conversion
[I had exactly this problem om my ur-q MC-1 conversion.
 After many hours of troubleshooting, I came to the conclusion that the
starter switch was faulty.  I took it out, and found a crack in the
plastic housing.  When I was turning it to the start position, it would
engage the starter, but not power the coil or computer.  I replaced the
switch assembly with the uber cheap VW starter switch (ask Rod at TPC)
for about $13.  No problems since..-Justin]

[Ben, try pulling 12v strait from the battery, for the coil and ECU.
I've seen people pull power from some srange places that may not be
getting power while cranking..Jim Green]

**** Checked wiring - with relayed power, I am definately getting power to
Coil 15.

[There are 2 wires on the primary side of the coil.  One gets pulsed and I
believe the other is 12V.  Does that check out OK?..  Mike]

****2 wires  yes, BL/R to 15 and Green to 1, but something is missing.

[[With key on I have power to the coil 15, and so far all checks indicate
things are as they should be.  Yet when the starter is engaged, I get no
spark - using a grounded plug on #1 wire to test and the fuel pump does not
turn on.  What is the trigger for the pump?]

The trigger for the pump is the switching signal for the ignition. It is
done that way for safety. If you are missing that signal, that is why you
have no spark and no fuel. You have to find out where that signal is being
dropped. There are two wires going to the coil, and the one not to term 15
is the one you need to check. I'm not sure if the turbos still have the ICU,
but if it does, check for power going to it. It doesn't rely on its mounting
for ground, FYI.

This is about as far as I can go without being there with schematics, hope
it helps.

Tony Hoffman]

**** Is ICU the Idle Stabilizer Control Unit I refer to as ISVCU?

> ----- Original Message ----- 
> From: "Ben Swann" <benswann at comcast.net>
> To: "Mike Sylvester" <msylvester at verizon.net>
> Sent: Thursday, September 30, 2004 4:53 PM
> Subject: Re: [urq] Re: No Start[spark or fuelpump] condition with no codes
> on MC-1 CGT conversion

> > Distributer was out, but lined up exactly the way it should be.  If
> > Distributor were out of window, there would be a code generated for
> > Anyway,  I'm positive it is dead on - consulted the factory training
> > to be sure.
> >

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