This is the least expensive OBDII code reader that I have seen. The price was $39.99 on sale from Harbor Freight Tools. It is called the CReader and it includes a short extension cable to improve plug access.
Also included is a brief user manual with the all-important list of OBDII code definitions:
Here is the Data Link Connector mandated by the EPA on all 1996 and later light duty vehicles sold in the U.S. There were also some 1995 Fords (including Rangers) that had at least partial OBDII capability. The location of the connector is standardized to the area under the driver's side of the dashboard. It is also present in vehicles sold in some other countries.
Just plug the CReader into the DLC while the engine is running.
If a Diagnostic Trouble Code has been stored in the PCM, the CReader reads the code and displays it. If there are multiple codes, it displays them in sequence. The display is repeated to give you time to write down the codes. Here, I have pulled the MAF/IAT connector to induce a Check Engine Light. The CReader correctly displayed codes P0102 (Mass Air Flow circuit low input) and P0113 (Intake Air Temperature circuit high input).
If the code reader remains plugged in with the engine running and reads and displays the codes 4 times, it then automatically clears the PCM codes. This is the display you will see if there are no codes stored.
For the price, this code reader is hard to beat. It is simple to use and works. I got mine for Father's Day.
"Universal Code Reader" part number 46030