B4 Determine Concern Is Internal/External to Control Module

- Install 60-pin breakout box and the correct Econoline 4WABS overlay.

- Key ON.

- Is the brake lamp On?

YES -- The antilock brake control module is functioning properly. To diagnose base brake system fault, Go to B7. B7 Check Fluid Level

NO -- Internal short to ground within the antilock brake control module has been detected. Replace antilock brake control module. To Verify concern is resolved, Go to B12. B12 Verify All Steps Have Been Completed