[T3] '73 Idle Test

William Jahn willjahn975 at gmail.com
Wed Aug 28 14:38:52 PDT 2019

Jim I sent the photo's . you can see the CSV connector it has no voltage on
it unless starter it engaged . I don't know why yet where the connector is
the one wire becomes 2 and seems to go into the car below it is the fuel
pump relay to CPU ground wire connector  . It might turn in the harness and
head to the #18 at the ECU why the two wires.

 I never had the double connector apart that feeds the ECU  it's  well
hidden behind the MPS and don't see any strands broken. I cannot get my
hands on it without removing the MPS so I have no idea if they are tight ,
they do look pretty filthy like old crud. Say if they are tight I can't say
I would know if they are tight with good contact or tight because of
corrosion or tight because the plastic connector is rock hard. There is so
much old filth I can't see the connectors.

 I didn't check the power relay need to remove the rear seat bottom to even
get at it. it's just far to hot here to deal with it now.

 If none of these are presenting an issue as in low voltage affecting the
mix then I have no clue what the issue is. As you said the main issue is
frayed wire strands or loose connections . If I don't find any issues with
the power to the ECU or in the relay then I have no idea what's causing
this issue. I know what it is not yet if I don't really check these
connectors or at least pull the ECU and the gray cover over it's connector
and check voltage at those two power wires while it's running I will never
know. It has to be running to really know if there is a voltage drop , need
to know what's coming out of the power relay should be running battery
voltage  from 30/51 to 87 and very close to the same at the ECU connector.



On Wed, Aug 28, 2019 at 11:57 AM Jim Adney <jadney at vwtype3.org> wrote:

> On 28 Aug 2019 at 10:26, William Jahn wrote:
> >  Jim :
> >
> >  I am just going by the Brown Bentley for wiring. So far it's been right
> as
> > far as the wiring diagram and FI wiring go.
> I'm going by the Bentley, too. The test wire is there for '72 but gone in
> '73.
> > I want to see if the power relay has any voltage drop between 30/51 and
> > 87 since this is where all the ECU power begins. If I see a voltage
> > drop there the power relay contacts have high resistance and either I
> > need to remove the cover and check and possibly clean the contacts
> While I've never seen a problem with that relay, I have had a similar
> problem
> with the fuel pump relay, and that's the same part.
> > Then move on to connector #20 and check both wire #16 and #24 to see if
> > there is high resistance in either one or both which will lower the ECU
> > voltage.
> Reasonable.
> > Any one of these could be what's causing the issue I have which is what
> > you pointed out one post back. I'm hoping this is where the issue is
> > and could be I never looked at connector #20 and after over 40 years
> > the 1/4" terminals inside this now black plastic once clear
> > connector/insulator may not have broken wire strands yet the brass
> > terminals inside exposed to the weather might be in real sorry shape
> > and have high resistance.
> While it seems to be extremely popular to take spade connections apart and
> clean them, time and weather do not affect them nearly as much as people
> must think. A connection that's never been apart is probably fine, while
> one
> that's been disconnected many times may be suspect. The key is in how
> tight it is: If it's hard to get apart, it's good; if it slips apart
> easily, it's poor and
> cleaning is probably not going to help. The problem is that you can
> certainly
> clean the male parts, but the area that makes most of the female contact
> is
> nearly impossible to reach without damaging the contact area.
> The key is that the contact area is under the end of the "curl" of the
> female
> connector. That's gas tight if it was clean when connected. It will stay
> good
> as long as it stays tight.
> OTOH, broken strands can be a real problem, but this only tends to happen
> on wires that have been treated roughly.
> --
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
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