The codes you got from the led/sw combo are from the diagnostic module
that monitors emissions related codes and alerts the operator via the CE lamp that fault/s have been detected and stored.
On that same diagnostic box, you will notice there are other pins. These are there to access other specific modules for code faults.
It is advisable to get these codes to help determine what the computer has detected in each system. This can be done by a DIYer by making a simple led/sw tool [simular to the built-in one you used]. With this tool, you want to go to both pins 14 and pin 8.
14 will tell you if the EA /CC module has detected a system specific fault and identify it, and 8 will do the same for engine HFM management.
This , along with the DM codes you have , gives one more info to help make a diagnosis.
The retrival procedure w/tool is the same as you used on the DM one...
If you get a Single flash , there are NO codes stored on that module...
You want as much info as you can get before changing parts....

Here is a tool pictoral that ,if you are handy and have a Radio Shack near by, will allow you to go get this info.
This tool will also allow clearing of the memory of these modules to get them back to mean, as Gilly has posted.
http://members.aol.com/ajdalton7/ledtool.jpg