Cant pull Codes?

The probabilty is that the signal gound (black/white wire, pin 46 on the computer) is broken somewhere inside the wiring harness. Turn the engine off and measure the resistance between the black white wire on the self test connector and battery ground. You should see less than 1 ohm.

Then remove the passenger side kick panel and measure the resistance between the Self test input (white/red wire) and pin 48 on the computer. You should see less than 1 ohm.

Repeat the process for the tan wire and pin 17 on the computer. You should see less than 1 ohm.

Diagram courtsey of Tmoss (diagram designer) & Stang&2Birds (website host)

Black_Mustang said:

what if they all check out?? looked like .9 for the black/white....

Click to expand...

Then you probably have computer problems.

Just in case you picked the wrong wire or missed something...

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Walmart.

This might sound really stupid, but is there something wrong with the jumper wire you're using on the actual test ports?