Delco/GM help

[john spears]

 Tim,

You need to check terminals G and H on your DFI module while cranking the
engine. G is the 18X signal from the crank sensor and H is the 3X signal
from the sensor. These are Hall Effect sensors, so you should have a nice
8-10 volt square wave while cranking. During crank you are operating in the
bypass mode, so the ECM is not even part of the picture yet. In other words,
you should have spark from the coils while cranking even if the ECM is
unplugged. It is all handled by the DFI module until the engine begins to start.

 Also, don't forget the basics, DFI terminal P should have 12 volts with the
key on, and DFI terminal N is the power feed line to the dual crank sensor,
it should have 10 volts on it with the key on.

My "guess" is a bad crank sensor, but this should help you pin it down.

             John Spears
Speartech Fuel Injection Systems

>From: Tim Willis <ddtcw at hunterlink.net.au>
>Date: Sun, 27 Apr 1997 00:38:59 +1000
>Subject: Delco / GM help
>
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>
>HI,
>
>I am lost in diagnosing an ECM problem for a friend on a 1990 Australian =
>Holden (GM) Comodore.  Engine is 3.8Ltre V6 with Delco ECM, it has 808 =
>written on it if that is of any use.  The crank angle sensor has two =
>pick ups on the c/s pulley, one with three marks the other with 18.  The =
>CAS connects to a DFI module, this is a module that the triple double =
>ended coils screw onto, I think it works out what coil to fire (ie the =
>firing order) and also passes signal back to the ECM which in turn tells =
>the DFI module when to fire the coil base on the usual sensors.
>
>The problem is that the all the pusles from the CAS are appearing at the =
>DFI module but nothing further is happenning.  I have swapped ECM and =
>the DFI module and engine does not fire.  The ECM code fault indicates =
>the DFI module.  I assume the ECM is OK as the faulf code can be read =
>and reset and the fuel pump is being controlled. =20
>
>Can anyone help me by identifying the signal that go between the ECM and =
>the DFI.  The DFI terminals connecting to the ECM are marked D, L, A and =
>B.  I have looked at them with a CRO while trying to crank the engine =
>and there is no real signal, except for about 1Vpp of noise.
>
>The DFI to ECM termianls are:
>
>DFI		ECU
>D		B5
>L		B4
>A		D4
>B		D5
>
>If any one can shed any light on this subject it would be much =
>appreciated.
>
>
>Thanx in advance
>
>
>Tim Willis.