Toyota FJ Cruiser Forum banner
  • Hey everyone! Enter your ride HERE to be a part of September's Ride of the Month Challenge!
1 - 20 of 93 Posts

·
Registered
Joined
·
1,066 Posts
Discussion Starter · #1 · (Edited)
I thought using the key to lock the doors in order to open the rear window was nonsense, so I added a button under the dash for this purpose.

Stock, it operates like this:
  • The rear door has an ecu. It is the orange box shown in the attached pics. This controls all of the functions in the rear door: locking, window release, wiper, and I think the high brake light and license plate lights (didn't investigate the lights yet).
  • There are 3 wires connecting the lock switch in the rear door to the rear door ecu (indicated by the red arrow in the first pic).
  • Turning the key to the right connects 2 wires (blue and purple between the plug at the ecu and the plug that connects the switch). This signals the rear door ecu to send a lock signal to the body ecu. The body ecu then locks all of the doors.
  • If you hold it for 2 seconds then the rear door ecu sends 12v to the window latch to release it. It bleeds the voltage down slowly to allow the latch to softly return to normal position rather than slamming back into place. More on this later.
  • Turning the key to the left connects red and purple (the purple is common to lock or unlock), signaling the rear door ecu, which in turn sends a signal to the body ecu to unlock the doors.
Now, when adding the remote button up front, there were a few ways you could do this:
  1. The button would perform the same function as turning the key to the lock position in the rear door (connecting the blue and purple wires). I didn't like this because then I'd have to unlock the doors after I used the button.
  2. The button would send 12v directly to the release latch. I didn't go this route for a couple of reasons. One was that you would have to add a diode to keep the 12 volts from your switch from returning to the rear door ecu. (I tried it, don't do it. Luckily I didn't pop anything.) The other reason is the soft return that I referred to earlier. (A third reason would be that you would need a relay if your switch wasn't strong enough to handle the current. The switch I used would not have needed a relay.)
  3. Hack the rear door ecu and separate the lock function from the window release function. Even though the circuit board in the ecu is not very complex, I don't have a diagram for it so this would be difficult or impossible.
  4. Disable the lock/unlock function of the rear door lock switch altogether and use the button to connect the blue and purple wires. This was the best scenario in my opinion. I don't need the lock function on the rear door anyway. If I'm at the back of the truck with my key in hand, I can just push the unlock button on the fob. If my key fob fails, there are still 2 other places to manually unlock the doors, the driver door and the passenger door.
Disabling the locking functionality was easy. Using the wiring diagrams, I identified which wire sends the signal from the rear door ecu to the body ecu. It's the brown/red stripe wire in the smaller of the 2 plugs in the rear door ecu (green arrow in the first pic). I chose to remove the wire from the plug rather than cutting it, so that I can replace it in the future if needed.

Now you just have to add the switch. I used a small momentary switch (Radio Shack part #275-644). All you have to do is make it connect the blue and purple wires. I removed the blue and purple pins from the plug and soldered my wires to the pins, then replaced the blue and purple pins into the plug. This way I didn't cut anything and I can always reverse the procedure to return to stock.

I ran wiring to the front of the truck and mounted the switch under the lower left corner of the dash. This switch requires drilling a 1/2" hole. (Tip: drill the hole smaller and use a Dremel to open the hole up to size, the edges will be neater.)
Motor vehicle Yellow Vehicle door Vehicle Car Vehicle Car Auto part Vehicle door Automotive exterior Auto part Automotive exterior Bumper

Now I can use the button or the key in the rear door to release the window latch, and using the key in the rear door will not lock or unlock the doors.
 

·
Registered
Joined
·
1,066 Posts
Discussion Starter · #2 · (Edited)
More pics

Close up of lock/unlock signal wire after I disconnected it. It's the brown/red stripe one turned back on itself and taped back into the loom.
Wire Cable Electrical wiring Yellow Close-up

Close up of 3 wires from door lock switch. My 2 wires to the switch are already connected here but one is hidden in the pic.
Wire Yellow Electrical wiring Electrical connector Cable

My wiring running to the dash. They're the gray wires attached to the main black loom. Each gray wire has 2 wires in it. I ran an extra set for future needs.
Vehicle Motor vehicle Yellow Car Vehicle door

Oh and another tip for the switch. If you use the switch I used and mount it in the same location, solder the wires to the switch instead of using plug-on connectors. There's not enough depth for the connectors and I broke the terminals off of the switch the first time when I put the dash back together. Had to replace the switch and then solder them instead.
 

·
Registered
Joined
·
1,066 Posts
Discussion Starter · #5 ·
SoonerFJ said:
How difficult was it to remove the lower panels and lining in the rear? I have been wanting to dynamat the rear cargo area.
Easy. But they've already put some dynamatting in it. You may want to do more, I dunno.

Rear door: There are 2 bolts in the panel near the top, behind pop-off covers, the rest is clips.

Rear cargo: Remove the screws from the threshold plate. Remove the screws from the cargo hooks on the driver's side wall. Subwoofer side will be more complicated but you can probably figure it out, I only worked on the driver's side. Remove the cargo hooks from the floor. The seats got me at first. To remove each seat, unsnap the cover from the back of it, it's all clips. Then remove the bolts from the hinges and take the seat back off. Leave the hinges attached to the body. Remove the 14mm bolts from the lower attachment points of the seatbelts. Everything should snap out from there. The floor mat just comes out, the side panels unsnap. Oh you have to remove the door thresholds before taking out the side wall panels.
 

·
Registered
Joined
·
1,132 Posts
Thanks. That will give me something to do this weekend. I am always afraid of breaking something, but your instructions are crystal clear. Great mod, BTW.
 

·
Registered
Joined
·
39 Posts
Great post... well thought out plan, clearly described, and seemingly worth the effort. I don't even have my FJ yet, but I can picture myself popping the window at a moments notice.

Thanks.

Mike
 

·
Registered
Joined
·
87 Posts
Nice modification! So do you need to hold your dash push button in for about 2 seconds like you described with the key?

Now, which button closes it again? :)
 

·
Premium Member
Joined
·
2,888 Posts
Nice mod - but for those of us with rear ladders its a moot deal - window can't be used !!!:eek:
 

·
Registered
Joined
·
1,066 Posts
Discussion Starter · #12 ·
ruebarb said:
Impressive, seeing I still need to go back their to lift the window open I don't see this saving any time. Nice work though.
But you don't need your keys. I hate when I'm working on it or cleaning it, I have the keys in the ignition to listen to the radio, and then I need the window open, I have to take the keys out of the ignition to open it. Or the keys are in the house, truck's unlocked, but I still need to go get the keys to open the window. I suppose you could just mount the button in the rear door panel instead of up front. Dang, why didn't I think of that sooner? I might add another button back there.
 

·
Registered
Joined
·
563 Posts
Very cool and useful especially if the car is running and someone needs to place something in the back without opening the entire rear door. Nice feature.
 

·
Registered
Joined
·
153 Posts
wow, that's great, ridge! nice, detailed instructions and photos.

i never even open my back window because it is such a hassle...

nice job! :)
 
1 - 20 of 93 Posts
Top