Ford 543 Fuel pump circuit open between the battery and the PCM
How to read it
Code 543 reads as 5 flashes, pause, 4 flashes, pause, 3 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 543 mean?
Fuel pump circuit open between the battery and the PCM
Common causes of 543
- Supply wire open circuit
- Fuel pump relay
- ECM
How to fix 543
- Check for supply wire open circuit
- Check the fuel filter and the fuel pump delivery
- Test the ECM last, only after every circuit test has passed
- Clear the code, then retest to confirm the fix holds
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. The three-digit row matches the description used in the data file.
https://web.archive.org/web/20030720231430id_/http://www.troublecodes.net:80/Ford/eec-iv.shtml
- Ford trouble codes, Contour, Escort, Mustang, Probe, Taurus and Tempo 1992-1995 (code, description, probable cause)
archived reference page (troublecodes.net via Wayback Machine)
Supports: code identity and probable causes
Independent table on the same archive site with matching code identity and a probable cause column.
http://web.archive.org/web/20160501223306id_/http://www.troublecodes.net:80/ford/contour-escort-mustang-probe-taurus-tempo-1992-1995/
- Ford EEC-IV trouble code table: code, fault location, probable cause (Crown Victoria, Mustang, Taurus, Thunderbird 1992-1995)
reference page (troublecodes.net)
Supports: per-code probable causes used for the page cause list and test order
Fetched 2026-09-30. The probable cause column is what the page lists, in source order, with the test order built from it.
https://www.troublecodes.net/ford/crown-victoria-mustang-cobralxgt-taurus-thunderbird-1992-1995/
Last updated 2026-09-29.
Report a correction for 543. Include your vehicle, the issue and a source if you have one.