78 Reinitialization check during self test
How to read it
Code 78 reads as 7 flashes, pause, 8 flashes on the check-engine light. Jumper the self-test input to signal return at the test connector, then run the key on engine off self test and the running self test, counting the check-engine flashes each time.
New to flash codes? The OBD-I code reading guide walks through the paperclip method, code 12, and reading two-digit codes.
What does Ford code 78 mean?
78. Reinitialization check during self test. This code sets when your vehicle computer detects reinitialization check during self test.
Common causes of 78
- Power to the PCM was interrupted
- Low or unstable battery voltage
- Loose battery or ground connection
- PCM internal fault
- Ignition switch interruption
How to fix 78
- Confirm the code and check for a recent battery or power interruption
- Check the battery cables, grounds and charging voltage
- Inspect the PCM power feed and connector
- Clear the code and retest after the power supply is steady
- Replace the PCM only if the code returns with good power and grounds