I'm installing an aftermarket TPMS monitor on top of the dash of my '08 Screw. While the monitor is powered by a rechargeable battery inside, connecting a charging cord to the power port would be a bit of a nuisance. A fused cord for permanently wiring to a power source is also provided. The two locations with possible sources of switched power (power that is on only when the ignition key is switched on) I see as being easiest for me to reach (I'm handicapped so I'm limited to where I can reach) is either the Diagnostic power connector under the dash or the wiring harness under the driver's door (the easier location to reach). Is there a switched source of power in either of those locations (I do not want any power being drawn when the truck is parked and the engine isn't running) and, if so, which wires?

 

If you're referring to the data link connector where a scan tool connects, that one has only an "Always Hot" power feed and doesn't meet your criteria.

If your truck is equipped with remote keyless entry, it should have the vehicle security module mounted to the inside of the cabin wall behind the panels behind the rear seat on the driver's side. There's a wiring harness bundle that runs through the door sill (under the scuff plate) that *should* include a white/blue wire that is the "Hot in Run/Start" power feed to the VSM. That one should do it for the power feed. You'd still need a solid ground, that would best be attached at the grounding stud that is behind the kick panel on the driver's side.

Good luck!

 

What about the radio wires? The Red/Black is switched power and the Black is ground.

 

Yeah, behind the radio might be accessible enough, the radio is pretty simple to pull.

Just to note, it's a pink/black wire for the switched power feed to the audio unit on this particular vehicle, not red/black.

 

I must've been looking at the 2007 diagram. That aside I think we're both wrong because the 2008 diagram shows a Blue wire coming off the acc/delay circuit, unless the blue wire is only when there is a navigation system installed.

 

How do you pull the radio?

 

Look at the 2008 F150 diagram, not the F250. Look for the circuit fed by fuse F1.

Dang, you having a rough day or something? Attention to detail, as my old drill sergeant from decades ago would have said.


Pop off the bezel, remove four screws, then pull the radio out enough to disconnect the electrical connector and antenna.

 

So I can use a flat blade screwdriver to pry off the bezel around the radio (it's the 6 CD changer, which needs unjamming or replacing anyway)?

 

The manual is not specific about any particular tool, so that usually means that almost anything should work. Pry carefully and take measures to avoid marring the visible finished surfaces.

if there is anything connected to switches, etc on the bezel, you'll also need to disconnect those.

 

Thanks for replies, guys!


Someone on another forum suggested that the power wire for the driver's side door power window (blue/black) would be suitable. I have no clue how I can easily get to that wire (keep in mind I'm a handicapped senior citizen) but I'm wondering if the same color combo wire for the rear driver's side door power window would run under the opening for the front driver's side door and be accessible by prying off the scuff plate on top of the floor of the door opening? I assume any nearby black wire would be usable for the ground (black) wire.

 

Thanks!...........

 

That circuit is on the accessory delay relay output. While it would technically work, it wasn't what you specifically asked for.

FWIW, it's a LIGHT Blue /Black wire which is a different color code than blue/black.

You'll have to determine what your capabilities might be, we can't tell anything other than what you report. You may want to simply take it to a shop to have the work done if the actions needed are beyond your abilities.

Good luck.

 

Actually, the accessory delay circuit would also work for what I want. I just don't want the circuit to be hot at all times to avoid running down my battery. I'll try to check it out tomorrow morning when it's cooler outside.


Thanks!

 

Well, I finally found the wires I needed inside the sill and got the wiring routed and connected. I'm too tired to post everything here (old age is for the birds) but if you want to see the blow by blow with pictures, you can see it here.


Thanks for all your help, guys, including the advice concerning the radio (that was an unexpected bonus)!