Code 18 - SPOUT out or wiring fault - look for short to ground in SPOUT wiring going back to the computer.
Possible bad TFI.
Remove the passenger side kick panel and disconnect the computer connector.
There is a 10 MM bolt that holds it in place. Disconnect the TFI module connector
from the TFI and the measure the resistance between the yellow/lt green wire and ground.
You should see greater than 100 K (100000) ohms.
Don't hold onto the metal tips of the probes when making measurements. You will get incorrect readings.
Next measure the resistance between the yellow/lt green wire on the TFI module connector and
Pin 36 on the computer connector. With the SPOUT plug in place, you should see less than 2 ohms.
The following is a view from the computer side of the computer connector.
Diagram courtesy of Tmoss & Stang&2birds
It is a good idea to use the sig under the user control panel (User CP) option. It allows you to post your car year & mods, which help greatly
when troubleshooting things. No, it is not there for us to snoop and see any "Secrets" you have hidden away under the hood. Be a good
stangnetter and update you sig for future reference & don't keep us guessing.
Would I be correct in saying that I am going to need a really long connection to measure the resistance between the TFI connector and pin 36? Any tips on the best way to go about doing this? I have a radio shack voltmeter (measures resistance also).
Also, what would inadequate resistance mean for the first and/or second tests (in other words, what would be the culprit)? How about if they're both good?
FINALLY: in the book that came with my code reader, I'm pretty sure code 18 said something along the lines of loss of TACH signal to ECA. Does this matter?
Results: Nothing. No resistance, no voltalge, nothing. I tried it with the ignition on and off. What could I be doing wrong? I tested at the terminals of the connector.
Are the batteries in your ohmmeter good? Select ohms, low range or Continuity on your meter and short the probe tips together. You should see .1-.8 Ohms.