Hi 1990 Bronco E.B. 5L MT.
The turn signals do not work. I replaced the turn signal switch & the flasher but still nothing this past week.
So before I changed the switch with the headlights on, brake lights on, flip the turn signal and they would go from bright brake light to dim running light and not flash. Now a week later on the new switch im back to square one.

 

Still sounds like the flasher, or something related to that. On my 89, the hazard flasher is over near the pass door under the glove box area. The tursignal flasher, is it over on the driver's side?(I can't remember).

Anyway, once you find the correct flasher, you should be able to pull it and not affect the hazard operation(just to make sure you have the right one). Once you are sure you have the correct flasher, with the key in run, engine can be running or not running, take the flasher out of it's socket, and take a testlight and probe the socket of the flasher. One side of the flasher socket should have power. If it doesn't, then I would check the fuse box for the correct fuse and see if it's good.

Here's a diagram, it looks like it is fuse #5.

http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=57171

 

Okay since you didn't mention it I'll ask...did you check fuse #5?

 

Funny story haha, after reading the replies I did check fuse #5 and that was the culprit. However after a couple days of driving the fuse blew again leading me to believe possible short in one of the tail light sockets?

 

The rear taillight turnsignal portion is shared with the brake lights. The brake circuit actually runs through the turnsignal switch, the switch decides if the brake signal will go through or the flasher signal will go through. In other words, the wiring to the rear and the bulbs in the rear for the turns are the same for the brakes. I say this, because you would think if you had a problem in the rear, that you would eventually burn out the brakelight fuse also.

So I think I would look over the front turn wiring first. That is also connected to the turn lights in the dash.

 

I picked up a replacement turn signal socket and compaired the ohm reading(1 ohms) of the new socket to all four corners of the bronco. The back sockets were identical at 2.4 ohms. The front passenger socket was 2.6 and the front driver socket was 6.4 ohms. Im hoping that the front driver socket is the culprit as to why my fuse keeps blowing?

 

Update:
I replaced the front driver side turn signal socket and everything was fine untill i put the park lights on and turn on lefr and right blinkers. Park lights on + right turn signal =fuse poped.
Strange thing that i didnt notice before. The radio went dark for a second then came back on. Sonow that is poonting me at a shorted headlight switch as the root of the issues?

 

First check for a bad ground connection on the right side.

 

I would not mess with the headlights. If the turnsignal fuse popped again, that is the circuit you need to stick with. If the fuse blew when you went to the right side, I agree with the previous poster, mess around with the right side front socket and wiring/bulb.

 

Update:
With a volt meter i tested the battery voltage with vehicle running, 14.56 volts. Then took the bulb out of the front right socket, turned on the park lights and turn signal and tested the accual voltage at each contact in the socket while having the volt meter attached to the ground strap in the socket. The turn signal contact my volt meter coyldnt keep up with it voltage, bouncing all over. The park light voltage was 14.06. Yet the grounding point on the top of the core support that is shared with two other grounds was the full 14.56 volts.
I think its an internal short in the front right socket. I ordered a replacement socket up and in a couple days we shall see.

 

I think we won the battle through attrition against the savy whit of the electrical gremlins!! Both front turn signal sockets were changed out and a fresh round of bulbs with fresh dielectric greese to back them up. And should the need arise there will be fresh sockets and bulbs as reinforcements bringing up the rear to lay seage against the nasty darkness of burnt out signal lights.

 

Another update:
Didnt last long.... Going to say screw it & replace the rear taillight sockets to, see if that helps, starting with the right one.

 

So i replaced the taillight sockets, took out the trailer wiring harnnes, and ran a test ground wire from the right rear socket (the front two turn signal sockets are replaced) to a grounding point with no paint or rust. It worked ...for a minute and got my hopes up. then the fuse blew. So I took test leads and ran them from the turn signal wire up to the front floor boards were my handy dandy multimeter was. I did a resistance test of the turn signal wire (orange w/blue strip) from the turn signal switch conector under the collum (with the contecter disconected) to the socket, it read 1.2 ohms. I did read an article that if the wire reads 5 ohms or greater, its an open wire/ground.

I did notice that when I would hold the right turn signal on without it being clicked on it did not blow the fuse. Only when it was clicked all the way over then did it blow the fuse almost instantly.


My next question is: Were are the grounding points for the turn signals in the factory harnnes?? Does each turn signal socket have its own ground? Or do they share a single common gound?
Or could the turn signal switch be faluty out of the box....




P.S. On a related note. after I changed out the rear sockets. I was doing a walk around and the 4-ways didnt work at first. with 4-ways on I pressed the brake a couple times and the 4-ways started working....

 

Grounds are not your problem. You have a wire somewhere that is touching ground. You have messed with all the sockets, so apparently none of them are the problem. Hopefully you can get it to consistently blow the fuse.

I am going with the previous diagnosis, you said when you press the brake the fuse does not blow, only when you do the signals. I still say that points to the front wiring/lights. I would follow the harness around up front, and see if it comes to a common plug somewhere near the firewall or on the inner fender. If it does, I would unplug the whole lighting harness that goes to the front, and see if it still blows the fuse. If it doesn't, then you know the problem is from that plug forward. If it still blows the fuse, then you know the problem is from there to the turnsignal switch.

P.S. Scrap the idea of unplugging the plug. I just noticed it feeds everything to the column, front lights and rear lights. So it would not do any good to unplug it and run a test. But I am going to leave the next post so you can see what is going on and get under there and check the wiring around the column.

 

This diagram in this link is for a 86. But I bet it is very similar to your 90.

Turn, Stop, & Hazard Lamps - ???Gary's Garagemahal

If you go to page 77 in the link, look at each front turn lamp, and follow the wire away from the lamp, each side goes to a connector "305". If you go to page 78, in the connector location list the say connector 305 is located beside the steering column.

In the above link it said connector 305 is shown in figure 139-2 on page 139. Here is the link for page 139. Looks like it's under the dash.

Speed Control - ???Gary's Garagemahal