Zillablog

In order to read DTCs on the check engine light, first locate the orange serial port shorting plug that came with the Hairball. This is a 6-pin telephone style plug with a single loop of orange wire shorting two pins. This plug, when plugged in, will short the RX pin to +14V. Be sure not to confuse it with the similar shorting plug that comes with some Todd / IOTA chargers, that one has black wire.
Codes will be blinked out on the check engine light on the Hairball. Four sets of blinks per code, with pauses in between digits.

The definitions of DTCs are located near the end of the Hairball Manual available here.
A copy of the relevant page is also an image at the end of this post.


To Read DTCs
1) Turn the key switch on. (It is not necessary to turn it to “Start.”)
2) Insert the shorting plug for only 4 seconds and then remove it.
3) The Hairball will now blink the current Operating Status code and stop.
3.5) Wait at least 10 seconds
4) Insert the shorting plug for only 4 seconds to view the newest stored error code.
5) Repeat step 3.5 and 4 to view older error codes, up to 5 can be stored.
6) The last code will be followed by a code of 1111.
7) Turn the key off after reading any number of codes to reset the reading procedure.