Home made lx470 AHC over ride (1 Viewer)

[BullElk]

So, I am a little confused. There are 2 wires to connect to (pin 4 &17), right? Why do you have 4 wires on your switch?

After making the cut he is splicing long wires into the four ends. Then attaching the four ends to the four prongs on switch. Basically putting a switch right where the wires were cut. But which wires to which prongs??

 

[tzyz]

So, I am a little confused. There are 2 wires to connect to (pin 4 &17), right? Why do you have 4 wires on your switch?

So you cut the 2 wires and extend the 2 wires originally going to the ahc to the switch and then you run another 2 wires back to the AHC connector. You're basically breaking 2 circuits. This is a double pole (2 circuit) single toggle switch(meaning that you toggle 2 circuits with 1 switch instead of having 2 switches for the 2 circuits)

 

[FxFormat]

I can't find any round based switches with 4 prongs, only see squared ones, anyone have any luck?

 

[1gr8FoSemty]

So you cut the 2 wires and extend the 2 wires originally going to the ahc to the switch and then you run another 2 wires back to the AHC connector. You're basically breaking 2 circuits. This is a double pole (2 circuit) single toggle switch(meaning that you toggle 2 circuits with 1 switch instead of having 2 switches for the 2 circuits)

Makes sense...thank you for the explanation. Excellent work.

 

[J1000]

Is there a switch(es) where I can control each corner independently?

Can probably use a potentiometer or something to modify the signal from one sensor at a time to possibly get that effect.

 

[BullElk]

Perhaps...???

Amazon product ASIN B079R7Y5RH
Or...anything like this should work drilling a round hole.

1 Pcs Heavy Duty 20A 125VAC ON-OFF DPST 2 position 4 Terminal Toggle Switch Car | eBay

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[ramangain]

When searching for switches the magic acronym is DPST. Double pole single throw.

 

[tzyz]

Perhaps...???

Amazon product ASIN B079R7Y5RH
Or...anything like this should work drilling a round hole.

1 Pcs Heavy Duty 20A 125VAC ON-OFF DPST 2 position 4 Terminal Toggle Switch Car | eBay

Find many great new & used options and get the best deals for 1 Pcs Heavy Duty 20A 125VAC ON-OFF DPST 2 position 4 Terminal Toggle Switch Car at the best online prices at eBay! Free shipping for many products!

www.ebay.com

That switch will not work because it is a DPDT(double pole, double throw), you need a DPST. Here is a link to the switch I used

Amazon product ASIN B07MV52SRM

 

[craaaazzy]

Subscribing for future project. Thanks!

 

[uHu]

Is there a switch(es) where I can control each corner independently?

No. The AHC doesn't work that way. Left and right are on the same hydraulic circuit, can't do anything to lift one side more than the other. Only when cornering at speed, the left to right crossover valve will close to reduce roll/lean.

 

[SHIfTHEAD]

So, I am a little confused. There are 2 wires to connect to (pin 4 &17), right? Why do you have 4 wires on your switch?

You have two coming in and two going out so it can turn on and off, else it's just Off.

 

[ramangain]

No. The AHC doesn't work that way. Left and right are on the same hydraulic circuit, can't do anything to lift one side more than the other. Only when cornering at speed, the left to right crossover valve will close to reduce roll/lean.

Who needs the fancy Mclaren suspension when we have AHC!!!

 

[BullElk]

You have two coming in and two going out so it can turn on and off, else it's just Off.

Any pics of splicing into the two wires?

 

[OwnerCS]

Is there a switch(es) where I can control each corner independently?

Citroen DS had something like that where an owner could lift one side of the car, then insert a jack post, then lower the suspension to contract the wheels up for changing a flat tire.

 

[LndXrsr]

Can anyone more electrically savvy than me explain why we need to splice into two separate wires to break the speed sensor circuit (i.e. why do we need a dual pole switch)? I'm not good enough with electrical diagrams to figure out what wires 4 and 17 do. Hoping maybe interrupting just 4 or 17 could do the trick. An OEM Toyota style single pole switch would be a really snazzy way to integrate this mod.

 

[midniteRNR]

Here's what I understand of this mod, in MSPaint form. You need a DPST switch because Pin 4 and 17 aren't connected to each other. The switch is there to interrupt the signal to both wires at the same time. When the switch is flipped to OFF, it disconnects both wires/circuits simultaneously, so the AHC system cannot function. With the switch flipped to ON, it is as if both wires are connected as normal, which returns normal function.

Disclaimer: I'm a mechanical engineer (not an EE) that hasn't done this mod on my own vehicle. If this is not how it works, I'll delete later.

 

[LndXrsr]

You're exactly right, that's how the switch works. It's basically two switches controlled by one toggle (or throw), hence the "dual pole single throw" terminology (DPST)

However, my question is more: why do we need to interrupt two separate wires if the intent is to interrupt the speed sensor feedback to fool AHC into staying at any height? Assuming only one speed sensor, what data is flowing through two separate wires?

My question is purely cosmetic. I'll buy a universal DPST switch if need be, but I'd really love an OEM look with a Toyota single pole switch accomplishing this task.

 

[Lalalx470]

If you want to use the Toyota switch you could wire the switch to a double pole relay and use the relay to make and break the pin 4, pin 17 connections. Adds a bit of complexity, but if it's all about looks, that's one way to do it.

 

[midniteRNR]

You're exactly right, that's how the switch works. It's basically two switches controlled by one toggle (or throw), hence the "dual pole single throw" terminology (DPST)

However, my question is more: why do we need to interrupt two separate wires if the intent is to interrupt the speed sensor feedback to fool AHC into staying at any height? Assuming only one speed sensor, what data is flowing through two separate wires?

My question is purely cosmetic. I'll buy a universal DPST switch if need be, but I'd really love an OEM look with a Toyota single pole switch accomplishing this task.

From PADDO in another thread:

These two wires are the wheel speed signals passed through from the ABS ECU. Red/white to pin 4 is front right (FRO) and red/yellow to pin 17 is front left (FLO). Normally these signals tell the AHC ECU that the vehicle is moving and the firmware commands an up or down height signal to get back to N as a function of speed. Remove this signal (by opening the double pole switch) and the AHC ECU doesn’t know the vehicle’s moving and allows it to stay at L or H as if you were parked in your driveway.

My understanding from this info and from how Techstream monitors sensor data, the AHC needs to correlate FR and FL wheel speed to verify that the vehicle is actually moving and not just in wheel spin or sensor failure. So both need to be interrupted to create an "all normal" feedback. If just one is interrupted, I would imagine that the system will default to a limp mode type setting. Again, not an AHC or wiring pro.

 

[LndXrsr]

Copy that, makes sense, two sensors = two wires. Thanks for finding @midniteRNR. and of course thanks to @PADDO for always having the details when it comes to AHC.

@Lalalx470, definitely like the sound of that plan, but I'll have to do some more reading on finding an appropriate relay and how exactly to make it work. 12V wiring is not my strong suit (not that household AC is either).