Anything wire under the hood that shows 12V when in drive/reverse and not park?

[snovvman]

Related to this thread:

My on/off switchable PWS mod "for off-road use only"

I'm not here to debate the good, bad, should, or shouldn't of PWS disabling. This is for off-road use only, at your own risk. I am not encouraging, suggesting, nor condoning this mod. I am simply sharing a technical solution for those who wish to, under specific circumstances, disable the PWS...

teslamotorsclub.com

I realized that I could use a relay to auto switch PWS to off when in drive or reverse, and allow the speaker/PA to work while parked. Does anyone know of a wire under the hood that is 12V energized when in drive or reverse, but not park?

Again, off road use only, yada yada... Not a discussion of opinions of good or bad to disable PWS, please.

Thanks.

 

[snovvman]

Bump. In case someone knows...

 

[NZGUY]

I'm looking at doing the same thing, with a relay connected to the reverse light wiring to disable the annoying UFO sound while reversing.

The closest wiring in the front of the cabin, and that's in a big harness. It easily splits off the further rear you go, which isn't ideal since the PWS speaker is all the way up front.

I need the speaker to be automaticlaly switched, and not completely disabled, since my '23 Model 3 only has the "superhorn" i.e. the PWS speaker makes ALL external sounds because there aren't any physical horns installed.

So I can't just do the normal PWS disable/resistor mod, as I won't have any horn at all!

Look here for the Model Y schematics and connector reference tool, I'm sure they're pretty much identical to the Model 3. Very useful info.

 

[snovvman]

Look here for the Model Y schematics and connector reference tool, I'm sure they're pretty much identical to the Model 3. Very useful info.

Been there, done that, have not found a solution yet.

 

[NZGUY]

Been there, done that, have not found a solution yet.

There's a 12v line which runs from a harness in the front of the cabin all the way to the rear. This could be tapped into for powering a relay to disable the PWS speaker.

The harness runs from the Right Body Controller, down under the door sills, and then up to the rear lights.

 

[snovvman]

There's a 12v line which runs from a harness in the front of the cabin all the way to the rear. This could be tapped into for powering a relay to disable the PWS speaker.

The harness runs from the Right Body Controller, down under the door sills, and then up to the rear lights.

But if the rear lights are CAN bus-controlled, then you still have to find an analog signal. The ideal solution is to sniff the CAN bus for gear status. I know it can be done--build a CAN bus sniffer for specific data, then the sniffer will show 12V when in reverse (and drive, in my case). This can be used to trigger the relay. I just don't have the knowledge to build a sniffer. I had a similar discussion in another thread where someone pointed to a CAN bus sniffer project, but it was not out-of-the-box.

 

[snovvman]

Here is the thread: Any wire under the hood that shows 12V when car is in...

 

[NZGUY]

But if the rear lights are CAN bus-controlled, then you still have to find an analog signal. The ideal solution is to sniff the CAN bus for gear status. I know it can be done--build a CAN bus sniffer for specific data, then the sniffer will show 12V when in reverse (and drive, in my case). This can be used to trigger the relay. I just don't have the knowledge to build a sniffer. I had a similar discussion in another thread where someone pointed to a CAN bus sniffer project, but it was not out-of-the-box.

The rear inner tail lights aren't CANbus controlled, only the headlights are (and maybe brake lights). That's unless something has changed in the past three months.

There are discrete lines running from the body controller to the tail light assembly. They're all "power in" for the fog, reverse, and tail lights, instead of a "lin" which indicates CANbus control line.

 

[snovvman]

The rear inner tail lights aren't CANbus controlled, only the headlights are (and maybe brake lights). That's unless something has changed in the past three months.

There are discrete lines running from the body controller to the tail light assembly. They're all "power in" for the fog, reverse, and tail lights, instead of a "lin" which indicates CANbus control line.

In that case, your problem is solved, right? Trigger off of the reverse and tap the 12V for the relay?

 

[NZGUY]

In that case, your problem is solved, right? Trigger off of the reverse and tap the 12V for the relay?

Yes that's what I'm going to do, and that's what you can use too, unless you've found another solution?

 

[snovvman]

Yes that's what I'm going to do, and that's what you can use too, unless you've found another solution?

I have not found another solution. I will have to double check, but I believe the U.S. cars also makes a noise while in Drive/foward when below a certain speed. This is why I wanted to disable the PWS in both Reverse and Drive.

In any case, if you try to implement this, please document the process as much as you can (photos are great) and let me know how it works out. Best of luck!

 

[snovvman]

Btw, ideally, the 12V power source is only "on" when the car is on. The relay would be wired such that PWS is enabled by default. This way, there is no parasitic drain from the relay.

 

[NZGUY]

Btw, ideally, the 12V power source is only "on" when the car is on. The relay would be wired such that PWS is enabled by default. This way, there is no parasitic drain from the relay.

I'll be sure to do a write-up of what I'm doing. I'm currently getting a list of parts together for it.

My goal is just to disable the reverse sound because it's simpler to do, and the forward sound isn't as noticeable so I can live with that.

I'd still rather not have the speaker fitted at all though! I was going to install the normal horns, but since there's no voltage going to the blanked off connectors, that complicates that plan..

 

[snovvman]

I'll be sure to do a write-up of what I'm doing. I'm currently getting a list of parts together for it.

Have you made any progress on this project?

 

[NZGUY]

Have you made any progress on this project?

@snovvman, I have all the parts required to tap into the reverse light wiring, but I'm just needing some time to figure out the tidiest/best way to do this and leave no traces of anything being tapped, since the car is still under most of its warranty.

 

[snovvman]

@snovvman, I have all the parts required to tap into the reverse light wiring, but I'm just needing some time to figure out the tidiest/best way to do this and leave no traces of anything being tapped, since the car is still under most of its warranty.

@NZGUY, thanks for the update. For the wiring bundle that goes to the reverse light, do you know where the most forward (toward the front of the car) accessible point is? If it's under the dash somewhere, then we just need to find a route through the firewall into the frunk. I do have the free subscription to Tesla's factory manuals, which includes the wiring diagram. I haven't looked to see if I can find the wiring location. That might be a good place to start.