Wiring Diagram

I'm hoping to flat-tow our 21 4R. I've confirmed the steering won't lock with the trans in N and manual transfer case in N. It doesn't like the fact it doesn't detect a key in this state (dinging, warnings, etc.) but I'll work through that (probably carista).

What I'd like to do is tap into the wiring loom under the fuse box (remove foot cover first). Lots of plugs there . . . . Need to identify turn signals and running lights (brake lights will work off the EvenBrake). I'll need to insert diodes to keep from back feeding. All I can find is generic wiring plans, nothing specific.

Does anyone have a pin-out of those plugs? or at least color codes for the wire bundle?

There are other options, but using the vehicle's lighting is the preferred one.

TIA,
- bob

 

In the absence of wiring diagrams, and knowing the 4Runner’s sensitivity to wiring changes, I’d tap into the wiring back at the tail lights to avoid interacting with any modules.

As an aside, you no doubt know more about flat towing than me, because I know nothing, but Toyota says not to do it.

 

Yes, I know all about Toyota's ultra conservative "no dinghy" policy, which they apply across all models, automatics, manuals, AWD, 4WD. It's such a small market they don't want the potential liability that goes with it. The 4WD T4R transaxle can be put in Neutral with the steering unlocked without the engine running (although it squeals constantly for me to put it in Park so it doesn't roll away). I've sorted out auxiliary braking and lastly trying to figure out rear lighting. The rear combo brake/tail lights have 5 wires running to them! "Old" incandescent lights use 3.

Which wires do I tap into? Yes, I'll use blocking diodes to prevent back feeding. Why do I need to rip apart all the panels front to back when the wires are right there next to the driver? Knowing how the tail lights work . . . . otherwise I'll be sticking tacky magnetic lights on the roof :-(

This is why I need a wiring diagram, better yet a schematic with wire coding and plug identification!

Flat towing . . . . it's a whole different thing.

- bob

 

What about the towing connector under the dash - yours doesn't have that?

 

The under dash tow connector doesn't have anything to do with turn signals or running lights but supplies power and controls a brake controller (like Curt, Redarc, Tekonsha, etc) when towing a trailer w electric brakes.

I'll be using that connector to power the EvenBrake system, a crude but effective box that pushes on the brake pedal when the tow vehicle (motorhome) starts braking (transmitter -> receiver in 4-Runner). The tow connector also supplies a brake light signal to the EvenBrake - when EvenBrake pushes on the brake pedal lights are activated but the EB needs feedback that the brake pedal is actually pushed.

https://www.etrailer.com/Tow-Bar-Braking-Systems/Roadmaster/RM-9400.html

But I still need to activate the turn signals and running tail lights. I'd like to do it by tapping into the harness (with diodes for safety) just before it enters the sub-floor panel. Pulling wires all the way back and over to the right side seems like a LOT of work! I just need to know which wires . . . .

- bob

 

Okay, thanks for the correction on the brake controller harness - I did use that connector for the under dash Curt brake controller which, after some finessing, worked well. The only thing I can contribute here is that (and I get that it’s a relative thought) it’s not “a lot of work” running wires front to back. Pop the bottom door trims and run multi conductor cable front to rear (did it several times on each side of vehicle). Should you ever have to “penetrate “ the firewall the easiest way I found was to heat up a pointed punch and create a small opening in one of several large pass through harness grommets. I know I haven’t answered your t/s circuit questions but perhaps may help with future projects? Good luck.

 

Any update on this issue? I too am in need of a wiring diagram or instruction from a knowledgeable member on how to tap into the tail lights for flat towing? Thanks in advance.