Hey all recent new member here with first post. I recently bought a ‘91 f150 xlt lariat 5.0 w/aod. There is this problem that I think is related to the turn signal switch. I have searched this forum and haven’t quite found my problem. First off the turn signal bulbs all work but just blink extremely fast. More of a flicker than a blink. However the left rear bulb doesn’t light with the brake lights or the hazard flasher. But it flickers with the signal light. They don’t all flicker just the side you actuate. Now I believe the brake lights share the same wire through the turn signal switch as the turn and hazard lights. Please correct me if I am wrong.
I haven’t changed out any parts yet as I want to be sure and not just through parts at it and hope it fixes it. Also the switch lever doesn’t “click” into place when you try to activate it. Just limply hangs for right turn and flops for left. It will cancel though when the wheel returns. Could this broken detents in the switch be cause and should it be replaced or just repaired?
The truck also has cruise controls in the steering wheel are they a player here or just a cost booster for replacement parts?
I am retired so the truck is just to “play” with and not needed for transportation. I look forward to any help you might offer and for sure I will be back as this is not it’s only problem. No fuel gauge, rear pump, hood release cable and needs exhaust real bad and so forth. I’ve lots to do.

Thanks in advance for your time and trouble.

Geoff

Well here’s an update to my problem so far. I discovered that the blink rate ( actually more of a flicker) could be corrected by a new flasher, heavy duty type. Also replacing the turn signal switch solved the left rear brake light issue as well. Now both brake lights work as designed in brake mode, hazard mode and signal mode.

Stumbled on to a fix for another problem by accident. While deciding to hack the floor of the bed to get at the fuel pumps, I took a chance and tried the rear pump. Standing outside the cab and with the 7”x10” hole in the bed floor, I was able to hear that the rear pump came on when cycling the key. Something unable to do alone with the bed floor covering it. I tried to start the truck but no go. So wondering if by chance I just needed gas, I poured in a convenient 5gal can and tried again and voila!! It runs and bonus is that the gauge for the rear works also. So I’ll just be running on the rear tank with the front for reserve if needed.

Now I just need to lengthen the driveshaft about 2” to put enough yoke into the rear extension housing and replace the front u-joint to quell that horrible vibration.
A new set of tires and the rest is visual which ain’t all that important if it runs like it’s supposed to.

So for now the list gets shortened.

Geoff