Hi guys, had to post this here as an absolute last resort. My father has a 2009 Ford F-250 Superduty with the 5.4l V8. Two days ago, he frantically woke me up from a nap because he could not get the truck out of park nor are the brake lights turning on when the pedal is pressed. I instantly thought Shift Interlock, did a quick google search and found that it can be the shift interlock or brake light switch on the brake pedal. I have since then replaced both to no avail as well as checking all fuses. I put a multimeter to the brake light switch connecter and am getting a steady 10.2v.
I am aware there is a bypass switch but that doesn't address the fact that he has no brake lights.
Can anyone provide some insight? Rather not take it to the dealer or an indy as I am a mechanic myself. Thanks guys. I really appreciate it.

 

Ignore the shifter; Just get the brake lights working. Brake lights are simple, you know all that. They don't even run through the ignition switch.

I think you ought to identify the fuse with some degree of certainty, inspect that, and then jumper the brake light switch. If the truck has cruise control expect that it might have two brake light switches.

if that doesn't solve the problem, you may need a wiring diagram after that.

 

I'm not fixing a '98 rusted out civic here, rather do things the right way.

 

Which wire and under what conditions?

That is not a valid value, it should be full battery voltage (12-14 volts).

Go check fuse F13 in the under-hood fuse box. If not blown, verify that full battery voltage is present on both fuse test points. If not, there's a problem in the fusebox. If valid voltage, then check for same voltage at gray-red wire at the brake switch, both with the pedal up and depressed. Repeat on the violet-white wire. Report results.

 

Did some proding around today. Put the multimeter to F13, showing 12v and when the pedal is depressed, it jumps to 20v showing that the brake switch is not the issue here. Put it to F12 which is Brake On/Off Relay Feed and it's showing 10.2v, and does nothing if i pump the brakes. Now what? This is making me mad >.

 

You need a new multi-meter, yours is defective. Any readings taken with it are unreliable.

 

Is it possibly it is the GEM (General/Generic Electronic Module)?

 

Good luck finding one of those in an 09 SD!

Go get a different meter and start over.

 

Still dealing with this problem, my dad got pulled over for no seatbelt and the officer didn't even notice his brake lights don't work lol.

Does the shift interlock need to be installed in a certain way? Put it in neutral, etc, etc.

Or could it be a pressure switch/sensor on the master cylinder? I am referencing this thread for this Message "Trailer Brake Module Fault" ?? - Ford Powerstroke Diesel Forum
He gets the trailer brake module failure all the time now as well.

 

Have you followed up on any of the previous advice?

See attachment.

No, there isn't one on an '09 SD that is part of either the stop lamp circuit or the shift interlock circuit.

The TBC module does require a valid BOO signal as one of its inputs. You're really need to pull the fault codes from the TBC module to know for certain why it's squawking.