Ford 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 How to Read Ford EEC-IV Self-Test Codes walks through the test and what the numbers mean. The general OBD-I guide covers the rest.
What does Ford code 78 mean?
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
Source
Source review recorded
Sources and review
Review: checked against the recorded source material.
- EEC-IV Ford trouble code table (MIL, description, type)
archived reference page (troublecodes.net via Wayback Machine)
Supports: code identity and meaning
Fetched directly. Code row matches the description used in the data file.
https://web.archive.org/web/20030720231430id_/http://www.troublecodes.net:80/Ford/eec-iv.shtml
Last updated 2026-09-25.
Report a correction for 78. Include your vehicle, the issue and a source if you have one.