This is my last weekend to prep the Subaru before heading to Davis to pick up the RV on Tuesday. I had one remaining task: installing the ReadyBrake DL100 brake indicator wiring from the Subaru brake pedal to the front of the car so I could have an indicator light in the RV cab when the Subi's brakes get applied.
(Aside: ReadyBrake includes the DL300 brake indicator light
with the ReadyBrute Elite package, but this only indicates that the ReadyBrake brake arm is being actuated, not that the toad's brakes are being applied. I would feel a lot better getting an indication of actual toad braking, even though it's more of a pain to install.)
Step 1: locate the wire connecting to the brake pedal switch that carries 12V only when the brakes are applied.
Problem 1: there's no room to work. I'm 6'2" with proportioned hands. Lying on my back in the driver's footwell, I can get one hand at a time up to where the brake switch is located. If I wiggle around I can get the other hand partially up there. I'm really glad I was alone when I did this because I said things about Subaru engineers that don't need to be repeated in polite company. Just getting the switch disconnected from the pedal socket was a challenge.
Problem 1, corollary 1: finding the right wire. I have a 12v probe tester, but with the socket unplugged from the brake switch there's also no current delivered to the wire. I found the always-on 12V supply wire easily enough, but there are three other wires going to the socket and no indication of which one might be the right one. Looking at the wiring at the actual brake lights didn't help, none of them appeared to match the color of the ones at the socket.
I was planning
to perform a real wire splice -- cut off some insulation, poke a hole through the strands, stick the new wire through the hole and twist then cover with tape/shrinktubing -- until the whole "no room" thing sunk in. I could hardly get my fingers to even reach the wires and I'm going to try some delicate manipulations? Hardly. At that point, some kind of parasitic tap is the only viable option. I tried to get posi taps but no one had them so I settled for t-taps.
I tried one wire by random selection and manhandled the t-tap into place by force of will. 33% chance, right? Yeah, didn't pick the right one. Get the t-tap off again (insert more kind words for Subaru engineers at this point) and pick one of the remaining two. 50% chance! This time I got it. My 12v probe lit up only when the brake was applied. Hallelujah. So now I've got a t-tap on the correct wire from the switch. That probably took about 45 minutes to an hour for something that should be 10 minutes tops. That should give some indication of the tight quarters. For future Subi users, I think the wire was the green and white wire, but I couldn't see all that well. Here's a shot of the t-tap (the blue plastic thing). If you can't see the wire color well, at least you can see the other wires and possibly the location.
Problem 2: routing the wire through the firewall. Starting from my existing tow plug, I pretty easily routed the wire along the frame, up behind the battery, back to the firewall and ready. There's a fairly large grommet on the driver's side firewall where much of the wiring goes through. That seems like a decent place to send the wire through.
Problem 2, corollary 1: there's no space again. For those following in my footsteps, you're going to want to slice a small hole and send the wire through at about the 4- or 5-o'clock position on that grommet in order to be able to get an angle on it from inside the footwell and pull it through. The problem with that
is that there so much stuff in front of the grommet that, once again, you're going to have a heck of a time angling tools a the right spot.
Here's a shot of the wire coming through the grommet into the footwell.
I should note that as delivered, the wiring included has a red wire and a black wire. The keen-eyed observer might have noticed that only the red wire appears in the photos. The original DL100 installation calls for running the wiring from the brake switch, through the firewall to the front of the car where you zip-tie a small, two conductor plug to the front of the car. On the RV side, there's a longer run to go from the back of the RV to the front where it'll go to the indicator light in the dash. They also include a short length that you plug in when the toad is hooked up to the RV. The idea being, you only have to plug in that extra cable between the RV and the toad to get it to operate. Great. But I already have a larger cable going between the RV and the toad to pass the RV's light indicators back to the auxiliary bulbs I installed. Why should I have another plug to deal with? Why not borrow an unused lead in the existing plug? And, if I do that, I really
only need to send the red 12V positive lead across since I can borrow the common ground already shared between the RV and toad.
So, that's what I did. Split the cables, discard the black, run the red. At the front of the Subi, I popped out my existing 6-conductor round socket and borrowed the unused center "auxiliary/electric brake" lead. Check with 12v tester and it lights up when I pull the ReadyBrake cable! Plugged the 6-round to 7-blade cable (another aside: please tell me the connection at the RV side is 7-blade) in and found the right conductors on the 7-blade side and tried it out... it works!
I plan to bring my 12v probe when we take delivery to verify the wiring at the RV before that first plug in to ensure I read everything right. Then I suspect I'll be able to borrow the wiring from the Tiffin-installed brake controller that's run from dash to tow connector to complete the circuit. I guess we'll see.
Hope this helps someone in the future.