How to Read Chrysler OBD-I Codes with the Key Cycle
What this covers
Chrysler put its early engine computers in Chrysler, Dodge, Plymouth, Jeep and Eagle cars and trucks from the early 1980s to 1995. The computer stores a fault code and blinks it out on the dash light when you ask. No scanner is needed. You cycle the key and count.
Watch the right light
The codes flash on the POWER LOSS light or the CHECK ENGINE light, depending on the model. On some cars the same bulb does both jobs. Watch the dash with the key on and the engine stopped and you will see it start to blink.
Cycle the key on and off
Set the parking brake and put the transmission in park or neutral. Turn the ignition key on, off, on, off, then on again, and leave it on with the engine not running. The light starts flashing the stored codes.
Read the flashes
Each code is a number flashed one digit at a time. One flash, a pause, then two flashes is code 12. Write the number down as it blinks. The light runs through the stored codes, then repeats them.
Code 55 ends the list
When the light has shown every stored code it flashes code 55. That is the end of the message, not a fault. If you only ever see 12 and 55, the computer has no faults stored.
Clear the code and recheck
Fix the fault first, then clear the stored codes by disconnecting the battery ground cable for a short spell. Drive the car like normal and read the codes again. If the light and the number come back, the fault is still there. A code points at a circuit, not at a part.
Look up your number
Find the code in the Chrysler OBD-I code list. Each page gives the meaning, the usual causes, and the order to check them. Start at the top of the check list and work down before you buy anything.