Turn signals inoperable. Already checked flasher(replaced), fuse, bulbs, with power to fuse and flasher circuit. Only have rear lights flashing on hazard flasher. No corrosion on bulbs and clearance lights and other lighting works fine.
Sounds like a bad multifunction/turn signal switch.
Testing the switch is simple enough. From the FACTORY electrical troubleshooting manual for my 87 Ranger:
With Eflashers turned off connect an ohmmeter to multifunction switch pins 44 & 9 & set switch to left turn. Good switch equals closed circuit. DO the same with pins 44 &3. Good switch equals closed circuit. Simple a that.
See if helminc.com has the eletrical troubleshoting manual for your E-250
Just checked & Helm does have the 88 f-250 manual, it’s 15 bucks. For fixing this and your next electrical problem you cant do better than this.
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The plug on the back of that switch.
It is common for the little lock tabs inside the grey gang plug to break allowing the wire ends to work loose ( especially for those who tilt their wheel a lot ).
A new gang plug body can be purchased at the Ford dealer.