Code EO42, C(3)I Ignition System
Code EO42 means the ECM has seen an open or grounded by-pass or EST circuit with the engine running, or an active ESC circuit during cranking.
- Checks to see if ECM recognizes a problem. If it doesn't set Code EO42 at this point, it is an intermittent problem and could be due to a loose connection.
- With the ECM disconnected, the ohmmeter should be reading less than 200 ohms, which is normal resistance of the ignition module.
- Checks to see if ignition module switches when the by-pass circuit is energized by 12 volts through the test light. If the ignition module actually switches, the ohmmeter switches to over 8000 ohms.
- Disconnecting the ignition module should make the ohmmeter read as if it were seeing an open circuit. If the ohmmeter has a low reading, circuit 423 is shorted to ground.
- Checks to see if ECM recognizes a problem. If it doesn't set Code EO42 at this point, it is an intermittent problem and could be due to a loose connection.