New to forum & I tried to search previous threads but didn't find anything...

Noticed that my High Mounted Brake Light and Cargo Lights were not working.

The bulbs were ok but I did find the fuse (15A #10 position) was blown. I replaced the fuse, but still have no lights.

I found a relay for the High Mounted Brake Light (#22 I believe) and swapped it with another (either the left or right turn and brake light, #23 I believe). Still no lights.

I checked for power at the fuse box (#10), both with the dome light switch rolled to the top & while pressing the brake pedal, and have none. Also checked position #9 and did have power so I think my method of checking for power at the fuse box is sound.

I don't have a wiring schematic so not sure where to go. Any advise is much appreciated.

 

Does the third brake light work? If not, check the plug that connects to the cargo light/brake light assembly. Check the bulbs again.

 

third brake light doesn't work either. IPulled the light assembly & checked for power at the plug. Have none.

 

I know there are several things that make the cargo light come on like unlocking the doors with the keyless entry, rolling the dome light switch to the top, opening the door, etc...

But the only way to make that brake light come on is to apply the brakes.

I'm guessing that the fuse for the cargo light (#10) is also the fuse for the third brake light. And I have no power to the fuse.

Anyone know where the power to fuse #10 comes from?

 

Check the YEL/GRN wire. It runs from the high mount stop light to main harness behind radio, then out to stop lamp relay.

 

Thanks, I'll check that wire.

 

I plan on chasing wires as JC8825 suggested but any other suggestions are welcomed.

The problem has to affect both the high mounted stop light and cargo light as both are inop. Also, I have no power to the fuse (#10).

Can anyone summarize the operation of the high mounted stop light and or cargo light?

i.e. does power go from the fuse box to the high mounted stop light and pressing the brake completes the ground?

or does power go from the fuse box to the brake pedal switch and pressing the brake completes the circuit allowing power to the HMSL?

The normal brake lights work, only the HMSL and cargo light are inop.

Thanks again

 

You have no power to fuse 10? I am looking at a wiring diagram and it looks like fuse 10 controls all lighting, upfitter switches, clockspring, adj pedals, sunroof, message center, 4x4 switch, traction control, parking aid switch, power sliding window switch. Are you really getting no power to the fuse? Are all of those things inoperable?

 

Only the HMSL and cargo lights are inop as far as I know. I haven't tried to use th adj pedals, power sliding window, or upfitter switches.

Fuse 9 is for interior dome light and it works. In fact I put a new fuse in #10 and it was no help so I swapped 9 & 10 to make sure the new fuse was good. When fuse 9 is removed, no interior lights, when 9 is installed, interior lights work. I also have turn signals and regular brake lights.

My wife said she noticed the cargo light inop about the time my batteries went dead (3 weeks ago). Someone told me there was a battery saver feature on the truck. I wonder if that could be related as my batteries went from good to not even enough power to turn the dome light on over night.

Thanks again for digging into this.