Ever since I started digging into electrics of Waggy I was amazed at lack of relays in FSJ, among other questionable decisions (due to cost cutting I guess)
be it headlights, power windows or locks, which are all driven by switches. For some reason they decided to use relay for fog lights, I guess thanks for it at least (but not for headlights that draw almost the same current). Between undersized wiring (mostly applies to headlights, which are wired with 16 gauge wire) which definitely does not get better with age, switches that suffer corrosion from moisture (hello, power windows and tailgate) and burnt contacts from high currents - all that adds up to crazy voltage drop by the time power finally reaches consumer, be it light bulb or window motor.
I already took care of headlights couple of weeks ago and I'm still amazed how big the difference is. I can finally drive Jeep at night! I also rebuilt power windows/locks/seats switches in front doors cleaning enormous amount of green/black gunk from them and it also paid off - both seats that I thought were dead came back to life, windows started rolling (well, most of them
), locks are now locking and unlocking... half of the time and on front doors only (but you can't always get everything at once, huh?). I even regained 75% of my power mirrors (driver's side does not move horizontally, but new mirror is waiting), and I must say that mirror switch was my least and most favorite at the same time. It's real pain in the rear end to take apart without losing anything and then put it back together, but amount of engineering that went into it...
Anyway, after cleaning up one more switch (now tailgate) I had enough of it, especially because in some time I'll probably have to open them up again to clean burnt contacts again and again. So it's time to put relays, relays everywhere! I must say that after cleaning switches my windows were rolling at acceptable speed, tailgate was struggling a bit - but overall it was not terrible. So my main goal was to take load off switches and make that part of electrical system more sensible and if I get things moving faster - couldn't hurt.
did a great job covering his relay journey with windows
, but I didn't want to have have dozen of relays somewhere in the cab and add bunch of wires. Why not put relays in the doors or in the tailgate? That way I can keep new wiring to a minimum and wire relay in right before the motor, leaving old wiring to carry low amperage signals only... I also wanted to keep original wiring as intact as I could (within reason of course) and to be able to revert to original scheme if I have to - think of failed relay and not having spare to replace it, exactly when you need to open the tailgate of course. Unlikely, but possible.
I needed something compact (space is at a premium) and waterproof (water can in doors), so after thorough searching I found relay box from GEP that takes two micro ISO relays and is waterproof. $80 for pre-wired on amazon, ouch (apparently amazon doesn't carry it anymore, can't find it there). I can wire it myself, save money and have some fun in the process. So after week of waiting I finally got all the parts:
Base, cover (I already put mounting tab on it), two SPDT relays, MetriPack 280 pins, cable seals and plugs, TPA (terminal position assurance) clip (that blue plastic thing in the middle), crimper and good 12 GA GXL wire. Hour later I had this ready:
Today was installation day, I decided to put first box into tailgate. There are six wires going out of relay box:
* 12V power
* 2 inputs
* 2 outputs
Power and ground are obvious and both are easily available inside tailgate, yellow t-tap is on "always hot" 12V wire and there is very convenient ground point right next to it:
Inputs/outputs may need a little explanation. Relay box is wired into 2 wires going from switches to motor that I cut and added connectors:
"Motor" side with male connector in the pic above would be connected to "output" side of relay module, while "switches" side with female connector is going to be "input" for it. I also decided to splice box in before safety switch to keep it's function - if I did it after it would only work for direction. Here's connected box, ready to test:
After confirming that everything works it's time to mount the box permanently and tidy up wiring a bit
There's enough clearance inside, so window shouldn't hit anything when going up or down
I also positioned the box so I can easily remove it if I had to replace relay - undo 1 screw and it's out (plastic holder stays inside)
last look before closing up
There were couple little things I wanted to do while I was in there. I was missing one rubber glass stop and the other fell off maybe a decade ago and was so dry I couldn't put it back on. Time to use 3D printer again (mounting plate for relay box was also printed) and now I have those
While I was printing I also quickly designed a plug for access holes I drilled earlier
Fits a little loose, but should be OK when it's squished by carpeted panel. I like it way better than my previous solution
Next step would be power windows (almost the same as tailgate) and power locks, locks being a bit trickier because of different wiring.