if it is stop/tail then make sure the bulb is correctly located the right way roung,also not unusual to have faulty new bulbs,also the top electrical loom joint onto the bulb holder is bad for corrosion on these,maybe worth having a look there,turn on the defective light and check there is a live feed at the connector,if there is then you know the problem is in the lamp assy,you can now get the bulb holder strip at motor factors which is a lot cheaper than a ford unit,good luck.
cdc, October 2014
