Turn signals fail when headlight or fan blower is turned on
#1
Turn signals fail when headlight or fan blower is turned on
2004 F150 Heritage Supercab, manual heater/AC. Turn signals stop if parking or headlights are turned on. Also if heater fan is turned on. I had the blower resistor problem where the blower only worked on high speed. Then turn signals stopped working. Upon researching the TS problem I found the fix to the blower resistor. Putting the new resistor in caused the TS to fail 100%. I put the failed resistor back in and get TS to work unless I use the headlights or parking lights. The blower stopped working at the same time the TS problem started. I have verified that all fuses and relays are working. If all the manual heater controls and blower are disconnected, the TS still fail when headlights/parking are used.