97 ZJ codes (or lack of)

[JackstandJohnny]

trying to pull codes on a 97 ZJ but cant.  OBDII just reads error and so does the 3 turnkey thing. i don't get anything.  anyone have the slightest idea why? engines a 4l
thanks

[LifesGrand]

I found this method, might help?

Here is another method that I found on the web
Extracting Fault Codes OBDII
Newer (OBDII) models - Put the key into the ignition, push down the odometer reset button, then turn the key to RUN with your finger on the button - and then release the button. The odometer will go through 1111111 through 999999, and then display the car's serial number. It will then show the error codes (it might show them starting with P). If this method does not work, try the OBDI method.

HTH!

[LifesGrand]

Also, someone has mentioned that the park brake may have to be set in order to pull codes, not sure if you have done this, but it's worth a try I guess?
& my first reply was a cut & paste from another site, so ignore the part about the obd1 method as I read your post...