Hey guys,
I have used this forum in the past for problems and it has been very helpful.
Recently the turn signals and brake lights on my 1996 F150 stopped working. I checked the fuse #7 and #13 in the fuses block as well as #15 in the power distribution box and they all seem to be fine. Then I decided to check for voltage at those places and figured out there was no voltage at #7. There is voltage at the PDB #15. This leads me to believe there is a wiring problem between the PDB and the cab fuse block since PDB #15 feeds cab #7. My question is, is there an easy way to check the wires? At first glance it looks like a real pain to get a good look.

 

Use a jumper wire to fuse #7 and see if they work.

 

If you checked with the key off then it is normal not to have power at fuse #7.
If the key was on then more than likely a bad plug at the Ignition switch, if not that you may have a bad Ignition Switch.
Fuse #7 has nothing to to do with the brake lights or the Hazard system.

Fuse #13 in the cab fuse block is powered by fuse #13 in the PDB.
Fuse #13 in the cab fuse block powers the BOO switch, Hazard flasher & the brake pressure switch.
If fuse #13 in the cab fuse block is bad check for a bad brake pressure switch as this has caused a lot of trucks to burn up. Take it to a Ford dealer and have the Mod done for free.

 

Fuse 7 is used for the turn signals.
Fuse 13 is used for the Hazard and Brakes.

Verify if the High mount brake light works. If it does and the
hazards, turn signals and rear brake lights don't, the multifunction
switch coluld be bad.

 

I would bet it is the Pressure Switch on the Master Cylinder blowing the fuse and he had better get it to a Ford dealer.
Fuse #13 is used for the:
1. Brake Pressure Switch
2. RABS Module
3. BOO Switch
4. Hazard Flasher



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He could also simply unplug the brake pressure switch on the master cylinder to test whether or not it is blowing the # 13 fuse.

 

Thanks for the responses. None of the fuses are blown, they are all still good.
The high mount brake light does work, so I will look into the multifunction switch being bad.
I also forgot to mention that the ABS warning light turned on at the same time the signals and brake lights stopped working. I guess that means its probably something coming off of the #13 fuse. I just find it a little fishy that fuse #7 has no voltage with the ignition switch on or off.

 

Please post if you find out anything about this...one of my trucks, my '96 is doing the exact same thing...good luck!
Roger

 

Fuse #7 Diagram:


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I replaced the switch today and now the hazards and brake lights work but the left signal stays on all the time and the right one doesn't work when I move the lever up and down. Any ideas?

 

Verify no pins on the connector or multifunction switch are bent.


Are all the left side lights on (LH Dash indicator, LH front and LH rear turn signal bulbs)?
If not replace the bad bulb.

If the lights are all on and the lights don't blink.
Disconnect Connector C231 at the multifunction switch.
Turn the ignition On.
Verify you have 12 volts on the Light Blue wire.
This is the 12 volts from Fuse #7.

If that's correct, the flasher is bad. (Did you install a replacement)?

With C231 disconnected. Look at what pins on the multifunction switch the Light Blue wire,
White/Light Blue and Orange/Light Blue wire correspond to on the multifunction switch.

With an ohm meter.
You should measure zero resistance at the multifunction switch pins where the Light Blue wire
and the White/Light Blue wire go to when the turn signal switch is in the Right turn position and
infinity/open when the turn switch is in the off position.

At the multifunction switch connector pins you should measure zero ohms at the pins where
the Light Blue wire and the Orange/Light Blue wire go to when the turn signal switch is
in the Right turn position and infinity/open when the turn switch is in the off position.

If any of the measurements are wrong, the multifunction switch is bad.

Here's a list of some of the wires at the multifunction switch connector C231.

Pin 1 Light Blue turn signal flasher input
Pin 2 Orange/Light Blue right rear turn signal and brake bulb
Pin 4 White/Red Hazard flasher input
Pin 5 White/Light Blue Dash right side turn indicator and front turn signal
Pin 8 Light Green/White Dash left side turn indicator and front turn signal
Pin 9 Light Green from brake switch
Pin 10 Light Green/Orange Left rear turn signal and brake bulb

 

Thanks for the help. I tested the pins on the switch and the multimeter showed the left turn signal connection being made no matter if the lever is up, down, or middle. Looks like its a bad switch. I plan on exchanging the switch for a new one and seeing if that fixes it.

 

Update: I took the switch back to get a replacement and they were out of stock so I got a refund. I went home, checked the old switch with the meter and it didn't work. I cleaned the pins with terminal cleaner, tested it again and it seemed to work so I installed it. Now everything works like new. It was just a bad connection between the contacts.
Thanks everybody for the help.

 

I've got the same issue, except mine is when the rabs kicks in. It blows the #13 fuse and then no brake lights and shift interlock occurs. I took out the other rabs 30 amp fuse just to quit blowing the 15 amp one, so I could get home with brake lights. My cruise control has always worked just fine but I'm not sure if that is related or not since I've read about the recall for it. Never had any problems with this until the rabs kicked in last night on the ice. Anyone have any idea what the problem could be? It's a 97 F350 4x4 460. Thanks!

 

would this part also be suspect if when lights are on left turn signal doesn't work but high mount brake light becomes brighter?