Lost brake lights, jumpered switch power ok.had left brake light then that quit. tried everything i can think of. No good. 4 ways work, taillights, ok turn signals ok. What am i missing. 90 f350 dually 7.5

 

So the bulbs ARE still working? Sounds like a brake switch/sensor problem then. I know on newer vehicles it's right behind the brake pedal. Not sure about our era truck though and i don't have my handy book with me.

 

Have jumpered switch power ok

 

What is the white switch above with hose on it?

 

Still no brake lights, does anyone have a diagram of the wiring?

 

Here's the schematic for a 88 which should be the same as a 90. Color of wires may be different. Circuit 511 appears to be your problem.

From the brake light switch is a Light Green wire that goes to the turn signal hazard switch.

If you measured 12 volts at the brake light switch and jumped out the brake light switch, there must be a break in the Light Green wire some where between the brake light switch to the turn signal hazard switch.

I've seen the same problem on GM cars. The wire for some reason breaks at the turn signal hazard switch. Replacing the turn signal hazard switch cures the problem.

 

How bad is it to change that switch?

 

Not difficult just takes some time.

When I replaced mine, I pulled the whole column and did the work on a bench.

Disconnect the negative battery cable.

Unbolt the steering wheel pad and pull the steering wheel.

Unbolt one bolt under the hood that attaches the steering column shaft to the intermediate shaft.

From inside the cab, remove 4 or 5 bolts holding the base flange of the steering column to the firewall.

Remove the ***** from the headlight switch and wiper switch.

Pull the left bottom dash cluster trim off.

Remove one torx screw and pull the right bottom dash cluster trim off.

Unbolt two large bolts holding the steering column to the bottom of the dash bracket.

Rest the steering column on the seat and disconnect the electrical connector at the ignition switch and the electircal plug from the steering column.

Pull the whole column out.

A couple of screws hold the hazard and turn switch assembly in place. I marked the steering column wiring harness wires and pushed all the pins out of the connector so the harness could be pulled up from the column. To install the new switch I removed all the wires from the electrical connector, and pulled them down the column and then reinserted the wires into the connector.

 

Its not bad. I have no cruise control... well, no buttons on my steering wheel and no tilt wheel. With that said.. Pop off the steering wheel cover by removing the torx screws, take off the center nut holding the steering while down and use a puller to pop off the steering wheel. DO NOT FORGET TO MARK IT TO LINE IT BACK UP RIGHT! You will also need to remove some of the plastic shield cover things around the steering column in order to get to the t/s switch harness. This will just make it easier to snake it through everything the steering column "clamps" or whatever. The supports that hold the column in place.

 

Does it have that spring on steering wheel that i need a special puller for? I'm going to pull the covering around the column tomorrow and see if the wiring is ok first, it would be nice to get lucky once. thanks.

 

Just need a generic puller. Don't need a puller that compresses a lock plate. You don't need to compress any spring to remove the turn signal/hazard switch.

The steering wheel is keyed to the steering shaft so you can't put it back on wrong.

 

agreed.

Mine wasnt, and I made that mistake.

 

Found problem was at connector at bottom of column.Working now but need new connector. Where can i find one?

 

Which connector?
The one attached to the turn signal hazard switch or the end that plugs into it?

 

Actually both but the switch end is lots worse.