davek9

But if it was an Auto.. pulling the relay would rule out a bad relay, due to the relay was mucking up the signal. There is more in that relay than a simple magnetic switch

davek9

No actually the signal looks just as the book shows, this software is made to use a sound card (the divider I built was a bit under 1/2 (.5) volts) and works really great for this type of work.

In this pic the signal is being pulled down form a bad component in the Kick Down Relay. (there are several).

jcorenman

Cool! That's slick, I'm off to try it. Thanks for sharing!!

dbrown928

I could use an internal pic of the voltage divider. Did you use a prefab circuit board or solder in line with wire?

davek9

OK I found what a good one looks like and even a vid while running :0

davek9

I'll have to look, I know I have it.
I just twisted them together and soldered them, then connected them to the phone jacks that I mounted to the box, butt ugly but I just wanted to be sure I could not short anything while using it., I have the drawing w/ values but it is easy to recalc.

dbrown928

Many thanks.

Everyone's input is greatly appreciated here.

More testing tomorrow.

Tails

With regards to a graphic of the CE panel, Alan Moore produced a "Porsche 928 Wiring Diagram Primer for the 1987S4s thru to 1995GTSs which shows the CE and connections and plugs and how to read the electrical drawings.

It can be downloaded from the web by googling it and suing the following:

Wiring Diag. Primer3 Apr 2009 ... Wiring Diagram Primer. - Available For Free Download. This is a small sub-set of the full document - "Porsche 928 Electrics". ...
http://www.928-electrics.com/wiring%...%20primers.htm

Davek9, great information re the oscilliscope via note book. I need to make one pronto to check out a few of my wave forms. Thanks.

Tails 1990 928S4 Auto

Tails

Davek9

Voltage Divider. Could you please post the drawing with values.

Thanks,
Tails 1990 928S4 Auto.

John Speake

If tach doesn't move, then you have no rpm signal to pin 1 LH ECU. In that case, the FPR will not be energised but that contradicts what you stated at the beginning of this thread ?

Please double check.

Are you sure you don't have a relay plugged into the kick down relay position ?

dbrown928

RPM signal through the CE panel will be the focus of this evenings testing. I will triple check the kickdown relay position to ensure it is empty.

The 928 electrics primer is a goldmine. I am happily signing up for the full document from Alan. Thinking about the years of experience and input in there it must be phenomenal. The price is nothing compared to weeks of frustration and a car that won't start.

davek9

OK working via remote VPN from home again today, I'll post the parts and a drawing here and also a short vid of a running signal on youtube under "crazy928guy" me

edit :
I'm going to get Alan's book, he has helped me many a time

mark kibort

I hate to hijack this thread, but I have no RPM on the tach, but the car runs fine. does that mean that im not getting a signal from the LH or EZK to run the tach?

Here is a pic of the LH outputs. with more detail.

great stuff here boys! thanks
mk

jcorenman

Yes, or your tach is dead.

Cheers, Jim

John Speake

Hi Mark, you are always the exception to the general rule :-)

In your case, the problem will be the link from pin 1 LH on fuse/relay panel to the tach in the dash, or no power to the tach....... etc.

If you look at the circuit of the fuse/relay panel for your MY car then you should be able to identify which connector/pin at the bottom of the panel carries that rpm signal to your dash pod.