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skucera 05-30-2010 07:29 PM

Turn signal switch wiring question
I'm trying to undo damage done to the wiring of my "new" truck ('91 F250 2WD extended cab). The previous owner (let's call him "Mr. Badwrench") butchered wiring from nose to tail to put in a 7-pin trailer light socket and a trailer brake controller. Whenever he didn't have the correct wiring available, he used whatever was lying around, including lacquer insulated household solid-core wiring from the 1960's and strips of household extension cord pulled in half. Scary.

My turn signals have never worked since I bought this truck a month ago. The brake lights haven't worked either. I fixed the front hazard flashers, but the rears just don't get any signal.

I had two wires poking out the Hazard switch hole in the steering column, so I figured I would pull the wheel to check the wiring in the column and see if I could find where these two wires came from. There doesn't appear to be anything that these two wires should connect to inside. The light green and light blue wires in the wiring diagram match the light green and light blue wires that still run out of the switch and down the wiring bundle at 10 o'clock relative to the steering column.

Everything looks present and correct, except those two extra wires that I have poking straight out the front for clarity. Can anyone tell me where these are supposed to go? Was there a second wiring bundle that ran down the column to another set of connections somewhere? Did these connect to another switch that Mr. Badwrench removed?

Thanks for your help.

F150xlt 05-30-2010 11:44 PM

2 Attachment(s)
Here's the schematic for an 88. Your 91 used the same turn signal/hazard switch.

Note if you purchase another turn signal/hazard switch there are two types.
One is for a tilt wheel and the other is for a non tilt steering wheel.

Attachment 203747

Next picture shows the connector pin out of the turn signal/hazard switch and
how to test the switch.

Attachment 203748

skucera 05-31-2010 12:11 AM

Thank you for posting these. These are much more detailed than my Haynes diagrams. I'm going to have to study these. These appear to match my simpler schematic in that they list light green and light blue wires as coming up the wiring bundle from Connector 305. There is no explanation of my two extra wires at the hazard switch. It's puzzling.

Oh, my truck does have a tilt wheel with cruise control. (Mr. Badwrench attached the brake light signal wire from a trailer brake controller to the light green wire on C305 instead of to the brake light switch, like the instructions for the controller directed him. I'm sure this led to confusing results for him, since the light green wire from C305 appears to be switched 12v power, which would in turn trigger the trailer brakes as soon as the ignition was switched on. Duh. I've already disconnected that incorrect splice.)

Did you scan your own manual? If so, thank you twice over for taking the time and effort.


subford 05-31-2010 07:57 AM

Deleted Deleted

F150xlt 05-31-2010 10:07 AM

There are 11 wires at Connector C305.

1) Pink/Black wire Circuit #158 Key warning switch to Buzzer
2) Light Green wire Circuit #511 Comes from Brake light switch
3) Light Blue wire Circuit #44 Comes from Turn signal flasher
4) Orange/Light Blue wire Circuit #5 Goes to RH Rear Turn/Stop Bulb
5) Light Green/Orange wire Circuit #9 Goes to LH Rear Turn/Stop Bulb
6) White/Red wire Circuit #385 Comes from Hazard Flasher
7) Yellow/Light Blue wire Circuit #460 12 volts for Horn Relay
8) White/Purple wire Circuit #296 12 volts from Fuse #6 used for Cruise
9) Dark Blue wire Circuit #1 Comes from output contacts of Horn Relay.
10) White/Light Blue wire Circuit #2 Goes to RH Dash Turn indicator and RH Front Turn Lamp
11) Light Green/White wire Circuit #3 Goes to LH Dash Turn indicator and LH Front turn Lamp

skucera 05-31-2010 11:15 AM

Ah, that answers some questions. Since Mr. Badwrench attached his brake controller's stop light signal wire to the light green wire on C305, the brake controller would get a pulsing signal to apply the trailer brakes when the turn signal flashed. :P

Now I just have to wait for the rain to stop before I can go out and do some more testing....


skucera 05-31-2010 05:49 PM

I figured it out. The light blue and light green wires run behind the turn signal switch an come up from behind to the wand selector switch. Mr. Badwrench nipped both of those wires so close to the connectors that I may not be able to solder them reliably.

So, how do you install a new turn signal switch? The hole through the steering column is too small to pass connector 305, and there isn't a smaller connector between it and C305. I suppose I can cut my existing wires a few inches up from C305 and use butt connectors to splice in a new one.... There's got to be a better way. Any ideas?


F150xlt 05-31-2010 07:22 PM

2 Attachment(s)
Here's two pictures.

First is a picture of the C305 connector end that goes to the turn/hazard switch. At the end of the connector is a plastic piece that pulls out.

That's the Red piece in the picture. Once you pull that out you'll see some plastic tabs. One for each wire that you press in so each wire can be pulled from the connector.

Then you pull the harness up thru the column.

Second pic shows the turn hazard switch assembly.

Remove the connector from the new switch and push the wires down the column then reinstall the connector.

Attachment 203745

Attachment 203746

skucera 05-31-2010 07:38 PM

That makes sense! It explains the diagrams showing which color wires go to each port on the switch.

Well, time to go shopping for a new switch....


F150xlt 05-31-2010 08:34 PM

Looks like there is enough wire to solder them back to the hazard switch.
If not just add/splice on some more wire.

Unplug the C305 plug at the base of the steering column. Remove two Phillip screws and a small hex bolt. The switch assembly can be pulled up. This should give you enough slack to resolder the wires.

I'll post a picture in a couple of minutes where the wires go.

F150xlt 05-31-2010 09:35 PM

3 Attachment(s)
1st and 2nd pictures show the turn/hazard switch so you can get a view of how the wire harness is positioned inside of the steering column.

Attachment 203742

Attachment 203743

It's hard to tell what the color of the wires are in this picture.

The picture shows where the Light Blue wire goes show as #1.
#2 is where the Light Green wire goes. There are two Light Green wires at that connection point.
You can't see the second Light Green wire which is underneath the first one.

Attachment 203744

TorqueKing 07-05-2010 10:23 PM

1995 F-150 hazard light relay flasher

I'm throwing those tags out there so the robots "google, bing, etc..." can find this if some other poor soul is trolling the universe to find a definitive answer on WHERE THIS THING IS!

For the 1995 F-150's out there:

There is a second flasher in the hazard circuit, and it is in fact a #550 that looks just like the one on the fuse panel located on the dash, below and left of the steering wheel. It is directly behind the turn signal flasher, ie, on the flip side of the fuse panel! I looked for hours for mine, but I wasn't going to find it because the old one was missing!

If your hazards are not working but the turn signals are, just look on the back side of that fuse panel and replace the flasher (or install one if there isn't one!). It's a $3 part and it will help you pass a State of Hawaii safety inspection.


skucera 07-05-2010 11:46 PM

Just to bring a little closure, and a more rounded search result in the future, I ended up buying a new turn signal switch a few weeks ago. With the hints that F150xlt gave me, I had the new one installed within an hour of getting home. It fixed both turn signals and brake lights... and as a special bonus it fixed my cruise control too.

Thank you all.


aindelli 09-19-2011 11:58 AM

1999 F150 Turn Signal Switch
I am trying to find the steering and turn signal switch wiring diagram for a 1999 F150. I have the part and have already removed the old switch, but when doing so, it kinds crumble in my hand and therefore I have no idea what wire goes where in the new switch. Can someone help?

skucera 09-19-2011 09:09 PM

Um, you'll want the "1997 to 2003 F150" forum. The wiring is utterly different on your truck than on our trucks. You have a multi-function turn signal switch like a modern car; we have a turn signal switch design like the one first used on the 1960 line of Ford cars.


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