Electrical gurus - help rewiring clutch start cancel switch

Hey yall - so I'm finally getting around to putting in my Meso switch panel and wiring in some more light switches.

Part of this task, and the one I've been dragging my feet on, is rewiring the stock clutch start cancel switch to use a ch4x4 small switch that can fit into the new panel.

I have the ch4x4 switch, and I found the wiring schematic for the factory switch in an old thread, but I really don't know where to go from here. I was hoping the wiring would match up and be easy peasy, but not so sure now.

Here's the schematic for the factory switch.


What I see here are -

Pink = IG (Ignition?)
White/Black = E (Earth?)
Beige = +S (Switched positive?)
Yellow = -S (Switched negative?)

And of course, the ch4x4 wiring:



Anyone with a decent background in deciphering electric diagrams that can tell me roughly how this might match up? Or is there a lot more going on in the stock button than what the ch4x4 is capable of?

Thanks!!

 

Oooh thats gonna be interesting. There is some circuitry in that clutch start cancel switch that allows it to self-shutoff once you've started the truck. Making that work with a regular, non-momentary on-off switch is going to be a hack at best.

You might be able to do it without the self disable by hooking up the Beige -> Green and Yellow -> Red 1, but no guarantees on what happens when that switch stays closed while the truck is running.

@caribe makaira might have some better ideas.

 

The way it looks to me is basically a latching relay with transistors. So you have voltage when the key is on, the switch is momentary, when you push it, it completes the circuit allowing terminal 2 and 4 to be connected until the ign is turned off.

so I would think a momentary switch between beige and yellow would allow you to use clutch start cancel but you would have to hold the button. Or get a latching switch and remember to turn it off. You wouldn’t need ign or ground

but I could be off track

 

Yeah this isn't a simple switch. I'd be stoked go get a small going myself, did a little hunting but I don't think Toyota makes this switch in a small for any other vehicles.

The black arrows with a line are diodes, saw blades are resistors, the coils are inductors and the parallel lines are capacitors. Getting the switch to return to impressed after ignition starts seems like the hardest part?

 

If you're down for a dissection project, and you could get your hands on a momentary switch, you could probably steal the circuitry from the original switch and wire it up to a new switch.

 

I suspect functional loss is worse than having one large switch. It is for me, maybe not OP though. A momentary would be easy but wouldn't be as convenient for single hand use. A pushbutton would be less safe for anyone unfamiliar with the truck if you forget to depress.

 

I think one of those inductors holds the switch in? So perhaps some metal on the faceplate? Might be possible to relocate the internals but that's pretty detailed surgery on small plastic parts. It would be badass though.

 

I agree with your reply to me. But I don’t think the switch is physically “held in” or “released” at least I don’t remember mine doing that.

 

That would put a damper on it. I forget how heavily cost engineered this stuff is. If you could take it apart, add a couple wires to connect the new switch, and put it back together, then wrap it up and stuff it behind the dash, that might work.

 

A mechanical latching relay could easily be installed with a aftermarket momentary switch and bypass the pcb based electrical latching switch

 

Ah, yeah it lights up but the engagement is internal. Even harder?

 

And the relay double pole so you get an indicator light back to the momentary switch? This sounds like the way to go

 

Exactly, and probably the easiest solution

 

I guess you wouldnt need a “latching” relay.... you could just use a regular relay. Not sure why I got stuck on the latching part haha

Ign - one side of relay coil
Other side of relay coil to switch
Switch to the W/B wire
The NO relay beige
And COM to yellow

 

Well you want the relay to hold itself up once you press the momentary switch, but I think that could be accomplished with a regular relay as well, maybe a diode. I need to draw a picture.

 

If it makes a difference, the ch4x4 switch I have is not a momentary, but it's instead an on/off type. Given that, can't I wire it in so when it is depressed, clutch cancel is permanently engaged? I don't really care about the auto return to disable that is built into the stock switch. I rarely if ever use this feature as is, but I'd at least like to retain use of it if needed.

 

Thanks for all the comments by the way, I am still catching up. I am very mechanically inclined but when it comes to electrical I know just enough to be dangerous.

 

Yeah, you could move the switch to the ign power side and loop the second pole back to the coil. The pole of the relay for the power for the light in the switch.

 

you might be ok with just the switch you have. Push it on, start truck, turn off. NP. But idk what would happen it it was always connected. Prob nothing haha

 

It’s just less safe. Think of partners, valet, car wash, etc. greater chance of lurching forward given how unfamiliar most are with MT. I wouldn’t feel comfortable with that. I believe any on/off can be changed to momentary. But momentary isn’t much more convenient than the clutch unless you’re outside the vehicle (long reach) or you have an ankle injury (in which case you probably shouldn’t be driving an MT)