Help with DME inputs and outputs Please
 

Hi i am needing to know how to test the sender units feeding my 86 3.2 DME
I have no spark and no signal to the injectors .
I have tested the DME relay OK, The DME control unit OK,
Any help from an expert would be great.
Thanks John

First guess would be the flywheel reference sensors or the cylinder head temp sensor but you have already started on the right track: Test, test, test!
(I am endlessly bothered by posts relating how many parts people have replaced.)


Also think about updating your signature with a location so if somone is local they can always tell.

Does this help?
http://forums.pelicanparts.com/uploa...1458395550.jpg
http://forums.pelicanparts.com/uploa...1458395568.jpg

I hope that you find this helpful...

Take a look at this Reference Sensor Testing Procedure:

How to test a Porsche 944 RPM and TDC sensor

Use these Instructions to further diagnose the car:

http://site.ecudoctors.com/tech-data/DME-Diagnose-Follow-up-Forms.pdf

I just went through this same thing myself. It drove me crazy. In my case my brain had some bad spots. Ingo Schmitz on this board repaired mine. It could also be the crank sensors as others have pointed out.

First make sure you get power to the DME when the ignition is ON. Check that the ICV is vibrating. If not an alarm or aftermarket alarm unit or the ignition switch could be at fault. Next up are the DME relay (swap it or jumper it). Once that is out of the way the next suspects are the sensors.

Testing the speed sensor should be done with a digital voltmeter set to AC Volt. Disconnect the DME, crank and measure the voltage between pin 8 and pin 27 inside the harness connector. You should see ~ 2V AC during cranking. For the reference sensor the measurement is a little more difficult because there is only a short pulse per rotation. But the voltmeter will still register something very small.

The continuity test (OHM setting) is less reliable. Even if the sensors Ohm out OK there were many incidents here where one of the sensors was bad.

Ingo