How Do I Read Trouble Codes on a 1993 Ford Ranger?

by Editorial Team
itstillruns article image
Jason Smith/Getty Images Sport/Getty Images

All vehicles manufactured from 1994 onward must be equipped with a code reader plug. This plug is connected to an automotive code reader which informs the user of any problems with the vehicle. On older vehicles, such as the 1993 Ford Ranger, this procedure must be done manually. The user must locate the self test plugs and set the vehicle in test mode. The user then reads the codes displayed by the flashes from the check engine light.

Step 1

Locate the two plugs required to perform the test on your Ranger. These are in the Ranger's engine compartment on the driver's side fender behind the air filter box. One is labeled the self test plug (STP) and is triangular-shaped with six pins. The other plug is labeled the self test input (STI). This plug is a small, single-pin plug. These plugs may also be labeled "EEC TEST."

Step 2

Connect a wire from the negative battery terminal to the STI. Ground the STI by hooking it to another piece of metal. Ground the battery as well by hooking another wire to the bumper.

Step 3

Turn the key in the ignition to the "Run" position. You will hear the fuel pump. When the fuel pump stops priming the system, you need to start counting.

Step 4

Look at the Ranger's check engine light. It will blink multiple times and then stop. The light will flicker to give a warning that the test is beginning. A code will blink and then pause for two seconds, indicating that it is moving on to the next number in the code. After the code is finished, it will pause for four seconds. If you miss a number, turn the key to the "Off" position, wait 15 seconds then turn it back to "Run." This will restart the sequence. You may need to go through the test several times until you get all the codes.

Step 5

Write each of these numbers down.

Step 6

Refer to a repair or service manual for your 1993 Ranger or use an online resource, such as, to determine what the codes mean. Note that there are different lists for two and three number codes.

More Articles

article divider