The indicators working or not shouldn't/wouldn't make any difference, more to go on is all.

Fuse locations, click on image of fuse box top link>1990 ford truck fuse box image - Google Search

(Says mustang but same as yours)

Something is screwy, haven't narrowed it down yet.

 

What if any effect/change if you remove the hazard flasher only?

 

Here this should help,

<a href="http://photobucket.com" target="_blank"><img src="http://i28.photobucket.com/albums/c250/danr1/1990turnhazardswitchdiagram.jpg" border="0" alt="Photobucket"></a>

 

...column....

 

still haven't figured out this problem... gr stupid truck is making me mad. maybe ill go buy another column and try it out...

 

i removed hazzard flasher only and it had no effect on the turn signals at all.

 

You need to run some simple tests to find where the problem is, for example.

Unplug the harness connector under the dash down at/near the base of the column, use a paper clip or short section of wire to jumper between the Lt blu and Lt grn-org wires, the left rear signal should flash.

If that fails try jumping between the wht-red and lt grn-org wires, the left rear signal should flash.

If first test fails something wrong with circuit between flasher harness connector or between the connector and tail light. Second is unlikely as you stated brake lights and hazards both flash.

If both tests make the light flash there is a problem with the switch or the harness running up into the column.

Test the wires, test each for short/continuity to ground, and to each other.

Use the diagram any suitable jumper lead and multimeter to narrow down the cause of problem.

 

ok guys i make a jumper between the Lt blu and Lt grn-org wires. whenever i did that i got the left rear wire constantly on.

after i tried that test i tried jumping between the wht-red and lt blu-org wires. whenever i did that i got nothing to the left rear at all. <--- I MESSED THIS TEST UP I SHOULD HAVE WENT FROM THE WHITE WITH RED STRIPE TO THE GREEN WITH ORANGE STRIPE NOT THE BLUE WITH ORANGE STRIPE. SO DOWN BELOW I TESTED FROM HAZARD FLASHER (WHITE WITH RED STRIPE TO EVERY CORNER OF THE TRUCK AND EVERY CORNER FLASHED AND BLINKED LIKE SHOULD

any suggestions?
any help is very appreciated.
thanks you guys very much in trying to help me threw this.

 

I did another test with ignition on at that same plug. there is 3 wires that i am getting juice to. one is light blue one, next is light blue with black stripe and last one is white with red stripe. all 3 of them wires are hot coming into steering column.

 

okay did another test i went from the hazard flasher and went ahead and jumped to each corner light of the truck. whenever i did that they all flashed correctly one at a time as i jumped the white with red stripe wire to each wire running to the corner of the truck. every light blinked correctly.

 

ok guys i make a jumper between the Lt blu and Lt grn-org wires. whenever i did that i got the left rear wire constantly on.

Ok, rear left light should have flashed but might have taken more time to build heat in flasher unit as its only one bulb load. Did you give it plenty of time to heat the flasher creating the flash?

after i tried that test i tried jumping between the wht-red and lt grn-org wires. whenever i did that i got nothing to the left rear at all.

Odd, because you have power to the wht-red wire, the rear left should have lit up minimum because you know the lt grn-org feeds the left rear and is "good" based on the the previous step. And the hazards had proven to flash to start with. Are you sure you had the key in the "run" position for each test including this one?

I did another test with ignition on at that same plug. there is 3 wires that i am getting juice to. one is light blue one, next is light blue with black stripe and last one is white with red stripe. all 3 of them wires are hot coming into steering column.

Yes, that one should have power key in run position, fuse #16.

Does your truck have cruise control?

As you can see in the diagram, W/cruise has a horn relay, w/o cruise has dummy horn relay jumper.

How the horn functions depends on its having cruise or not.

With cruise horn button provides the ground needed at the relay, W/0 cruise horn button simply breaks/makes the power feed circuit.

However unplugging the harness connector eliminates any that from the equation. If any issue is in the column wiring or directional/hazard switch or the slip ring, jumping the connections there bypass all that and should result in lights that flash correctly. If everything to it and down stream of that connector is in working order.

Add in more lights if needed to build more heat the flasher, do so quicker, jump from Lt blu to lt grn-org and add in lt grn-wht for example.

That should have the left rear, left front and dash indicator lights loading the flasher unit to insure enough load to create a flash. However one bulb should do it, just take longer to heat up and "flash".

Be sure you have the key in "run" position when testing.

 

hey yes i made sure key was in the ON position every test i did.

 

did another quick test. u took the flasher completely out and i went from the blue wire to the green with orange stripe wire and the rear light still comes on and stays on even the there isn't even a flasher in. also i am still getting juice to both pins in the fuse panel where the flasher hooks into. shouldn't there be only one side getting juice not both sides?

PS the truck DOES NOT have cruise control.

 

whenever i tested from the white wire with red stripe to any wire running to the light on any corner of the truck the light will blink.

 

did another quick test. u took the flasher completely out and i went from the blue wire to the green with orange stripe wire and the rear light still comes on and stays on even the there isn't even a flasher in. also i am still getting juice to both pins in the fuse panel where the flasher hooks into. shouldn't there be only one side getting juice not both sides?

Ok that is flasher out, column unplugged and jumping at its harness connector?

If so and I believe that's what your are saying then yea that's gotta be the problem right there.

At the flasher socket with the flasher removed, the flasher connector feed by the Ppl-org conductor should have power to it key in "run" position via fuse #5. The other side the flasher socket, the connector with lt blu conductor should be dead.