I have followed the testing procedures outlined inthe Haynes manual and I have determined that I have too much resistance in the spout circut between the PCM connector and the spout connector. According to the wiring schematics in the manual that is a single wire that doesn't connect to anything else. Can I just run a new wire between the two points for testing purposes.

 

Post removed

 

You're right. The Haynes manual had me checking the wires from the spout connector to pin 36 at the PCM connector. The yellow/green wire

 

Post removed.

 

When checking the ac voltage at different points in the harness the voltage is too high. It should be 3v-8v. I am getting up to 14v. I checked resistance between the spout connector and th PCM connector it is in spec. But when I check resistance between the spout connector and ground it is not high enough as in a short to ground.

 

I have installed a new Motorcraft icm and was working towards the processor. I have a backfire under load. I have replaced the timing chain and set the base timing at 10*. New coil cap rotor wires plugs. I am running out of ideas.

 

I think you mean DC voltage.
I will take back what I said above as it seems the codes are different back in 86-87-88 than in the 1990s.
I need to know what the code 18 was (KOEO, CM or KOER)?
As all three 18 seem to mean something different.

 

The manual said ac voltage. I realize the difference. The only time I normally see ac voltage is when the diode in the alternator is bad, but both of my volt meters show ac voltage at the icm connector. The 18 was cm.

 

The 1989 Ford shop manual says (and I would think an 1986 would be the same) that a 18 C means:
Loss of tach input to Processor/SPOUT circuit grounded.

The earlier posting was from the 1992 Ford Shop Manual.
This is the first time that I have noticed that a code had different meaning in a different year.

I will go along with AC, just never check that wire with a meter:


/

 

I think the wire from the spout connector to the PCM is going to ground. And according to the wiring diagram that is just a solid wire so I am going to try and run a jumper wire in its place and cut out the old one. Not permanent but just for diagnosis.

 

I think the older Ford shop manuals have the C18 code wrong in there quick list that Haynes manual has copied.

The same 1989 Ford shop manual in another place says for the pinpoint test for C18 go to N3.
And N3 says that C18 indicates a lost of IDM processor input.
So I guess the 1992 manual was right and the C18 has nothing to do with the spout wire.

As I had posted above you may have an open resister in the IDM wire.

 

Do you have a way for me to test for that?

 

Test the circuit for continuity to ground, if none found likely need to replace the ICM to correct the problem.

 

Yes:
Key off.
Disconnect processor 60 pin connector. Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
DVOM on 200,000 ohm scale.
Measure resistance between pin #4 of the processor 60 pin connector and the ignition coil negative terminal.

Note that there is a 22,000 ohm resister between the pin #4 of the processor 60 pin connector and the ignition coil negative terminal.

Is the resistance between 20,000 and 24,000 ohms?
If YES we will go on to another step.
If NO service the open circuit.
RECONNECT the e-core ignition coil and processor 60 pin connector.
Clear codes.
Rerun self test.

 

Up to 14 volts is OK.
The Ford Manual says:
"The SPOUT signal has a variable duty cycle with amplitude that varies from 0.4 volts to VBAT". It does not say AC or DC.
I do not know how it would be a short to ground if you are getting 14 volts.
The resistance to ground with the computer and the ICM disconnected is more than 10,000 ohms.
If you had the computer and the ICM were still connected then your reading does not count.