XYZ switch

[lewy]

perhaps a dum question but what does the XYZ switch do.I know the electrical parts talks to the computer but what about the mechanical part [spline into the gearbox]is its only job to engage the park mechanically and the gear selection is left to the electrical side.why i ask this is can the electrical side be bypassed and switches put inside the cab somewere.

[rick130]

perhaps a dum question but what does the XYZ switch do.I know the electrical parts talks to the computer but what about the mechanical part [spline into the gearbox]is its only job to engage the park mechanically and the gear selection is left to the electrical side.why i ask this is can the electrical side be bypassed and switches put inside the cab somewere.

It acts as an inhibitor switch, ie. if the 'box isn't in Park or Neutral it won't let the car start, as well as telling the electronic box of tricks exactly what gear + park and neutral has been mechanically selected.

[lewy]

It acts as an inhibitor switch, ie. if the 'box isn't in Park or Neutral it won't let the car start, as well as telling the electronic box of tricks exactly what gear + park and neutral has been mechanically selected.
So the functions D,R 1,2,3 of the XYZ switch could be moved to say a rotary switch inside the cab,but the cable is needed to put the box in park which is a mechanical process.

[Slunnie]

So the functions D,R 1,2,3 of the XYZ switch could be moved to say a rotary switch inside the cab,but the cable is needed to put the box in park which is a mechanical process.

The cable selects all of the gears and the XYZ needs to reflect that for the starting inhibitor, transmission computer control and the dash read out. I suspect if you substituted the XYZ for a switch in the dash you would just end up throwing loads of faults.

Why would you do that? It wouldn't end up being full electronic control like the ZF 8HP by doing that.

[Tins]

It's also a fair bet that such a modification could render the vehicle unroadworthy, with consequent impact on insurance etc.

[LuckyLes]

You already have such a switch in the cab, cleverly disguised as a gear stick.

[sierrafery]

The electrical side of it can be emulated hence the compushift thing: Compushift – Ashcroft Transmissions (https://ashcroft-transmissions.co.uk/product-category/compushift/)

[johnp38]

perhaps a dum question but what does the XYZ switch do.I know the electrical parts talks to the computer but what about the mechanical part [spline into the gearbox]is its only job to engage the park mechanically and the gear selection is left to the electrical side.why i ask this is can the electrical side be bypassed and switches put inside the cab somewere.

The XYZ switch combines the function of the old school neutral safety switch that is in hydraulic shifting boxes as well as the function of signalling to the Transmission Control Unit (the separate auto trans electronic control unit) and I think the engine ECU (too lazy to check the circuit diagrams) what position the auto trans lever is in (ie P R N D 3 2 1)

The 'spline into the gearbox' as you refer to it also moves a piston and re routes fluid in the valve body , so what you are driving at, which is to do away with the mechanical shifter and use electronic control in the cab to change gear selection, will work better by using a servo motor of some sort or a linear actuator to still move the 'spline going into the gearbox' while having a rotary switch or other electronic setup in the cab which controls the servo motor/ linear actuator but leaving the XYZ switch where it is.

A Compushift replaces the factory transmission control unit, but still needs the XYZ switch or an equivalent (ashcroft has a replacement for the xyz switch that works with the compushift) to tell it what position the "spline" is in (ie P R N D 3 2 1)

Can I guess you mean 'I want to get rid of the shifter and look cool with a rotary or push button selector how do I do it'

[lewy]

'I want to get rid of the shifter and look cool with a rotary or push button selector how do I do it' That's it you have caught me out,i am 68, short, fat, bald, I want to look cool again.or perhaps i don't want to get under the disco ever again to change that bloody xyz as here in Darwin anything electrical simply don't last in the Humidity or the 1200mm of rain we drive through every year.but thanks for the reply it has made it pretty clear as to how it works,might look at the ashcroft offering.

[johnp38]

i don't want to get under the disco ever again to change that bloody xyz as here in Darwin anything electrical simply don't last in the Humidity or the 1200mm of rain we drive through every year

Ok, i see the practical reasoning now, well actually to get rid of the XYZ from below you need to look at the internal electrical function and just duplicate it at the other end in the centre console so it still changes as you move the selector lever. It would be a pain in the butt to be moving the selector to drive then having to also move a dial or switch separately to make sure the transmission computer knows whether you are going forward or backward.

The compushift still needs the XYZ down below or its own sliding potentiometer setup in the same place, still copping the wet you are trying to avoid.

I haven't had the XYZ screw up (yet) so no practical experience with it but surely there would be a few tips on the forums on rebuilding it a bit more watertight ?

Can you extend/modify the pivot pin on the selector and hang it off there instead ? Not sure how you go for space.

I recall some of the previous vehicles I had, the switching was in the console and just rod and lever down below.

But to reiterate a compushift will not eliminate the issue down below.

At least you didn't mention ugly (oops I mean appearance challenged) so you're still up on me [biggrin]

[rick130]

I agree it's in a **** of a spot, and the LH AC drain drips onto it, too.

I stripped and rebuilt mine back in December and it had bugger all moisture inside, but enough to stop the car starting. The joys of lots of causeways here and lots of rain. And an AC that runs all year round. I think we're the second wettest part of the state? (no where near what Tully, Nth Qld or Darwin cop though!)
It used to regularly throw trans faults/limp mode/3rd gear whenever I drove through a causeway, too. <_<

I used a nice smear of silicone grease on the O ring and packed the cable entry, too. How long it lasts before playing up again = how long is a piece of string?
You will still need that cable and lever to move the internal piston to manually change gears on the trans, but how much mucking around is there to move the micro switches to the shifter area?
Anything can be done with time and $$, I've just never thought about it.
I suppose it's the compromise that happens when you convert a fully hydro-mechanical trans to electronic vs a clean sheet of paper ECU controlled 'box.

[Slunnie]

but how much mucking around is there to move the micro switches to the shifter area?
Anything can be done with time and $$, I've just never thought about it.
I suppose it's the compromise that happens when you convert a fully hydro-mechanical trans to electronic vs a clean sheet of paper ECU controlled 'box.

Sounds like a Td5/8HP conversion. :lol2:

[rick130]

Sounds like a Td5/8HP conversion. :lol2:

😂