Cant pull Codes?

[Black_Mustang]

i have an 88 5.0 5 speed thats been having a few issues...long story short i am trying to pull the codes but im not getting anything?? (using a test light) the light stays lit with key off but goes out and does nothing with key on....the fuel pump/relays prime when i switch it, sometimes twice....but nothing more happens. i have tried using the battery ground and harness ground but still nothing

anybody????? :damnit:

 

[jrichker]

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]

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

 

[jrichker]

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

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.

 

[Black_Mustang]

ive done it a million times thats why im so puzzled....im chasing down what seems to be a pretty bad mis/misfire all throughout rpms....maybe its all connected

 

[sgarlic]

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