hobbit
Well-Known Member
While I've got things apart [again], I thought I'd check out the functionality of VESS control which
isn't provided with a switch in the US market. Behind the block of buttons near the driver's door,
referred to as the "left crash pad" in our doc, there's a connector into the switch block, and it was
an easy matter to backpin the appropriate green and grey wires and have a play.
At startup VESS defaults to on, with the LED output on. I hung my "noid box" off it so I could audibly
tell when the state changed. The green wire sources a little over 3V with a maximum current of 1 mA,
so grounding it is perfectly fine and seems to be what an installed switch does anyways. The VESS
state toggles on a rising edge above about 1 volt, i.e. when you let go of a grounding button.
From this I thought "hmm, what if you held the disable input near ground for some time at startup",
i.e. toward a passive VESS-disabler consisting of nothing but a largish capacitor to ground. The
disable line would take some delay time to charge that past threshold. It actually works, but also
needs a discharge path to drain fully when off. Using a 500 uF cap in parallel with 100K, I powered
up and heard the noid box for about half a second. It took several seconds to discharge after power-
off, so fully passive might not be reliable for rapid operation sequence.
So in general, an auto-disable would only need to hold the line low at power-up for a little while and then
let it up. No fancier pulse stuff needed.
Frankly, it's still easier to pull the speaker connector up front. It's a little fiddly the first time because the
latch is hard to press, but I snipped the latch tab off mine so it's easy to put the connector back for any
"compliance" purpose that comes up, and pull it again later.
_H*
isn't provided with a switch in the US market. Behind the block of buttons near the driver's door,
referred to as the "left crash pad" in our doc, there's a connector into the switch block, and it was
an easy matter to backpin the appropriate green and grey wires and have a play.
At startup VESS defaults to on, with the LED output on. I hung my "noid box" off it so I could audibly
tell when the state changed. The green wire sources a little over 3V with a maximum current of 1 mA,
so grounding it is perfectly fine and seems to be what an installed switch does anyways. The VESS
state toggles on a rising edge above about 1 volt, i.e. when you let go of a grounding button.
From this I thought "hmm, what if you held the disable input near ground for some time at startup",
i.e. toward a passive VESS-disabler consisting of nothing but a largish capacitor to ground. The
disable line would take some delay time to charge that past threshold. It actually works, but also
needs a discharge path to drain fully when off. Using a 500 uF cap in parallel with 100K, I powered
up and heard the noid box for about half a second. It took several seconds to discharge after power-
off, so fully passive might not be reliable for rapid operation sequence.
So in general, an auto-disable would only need to hold the line low at power-up for a little while and then
let it up. No fancier pulse stuff needed.
Frankly, it's still easier to pull the speaker connector up front. It's a little fiddly the first time because the
latch is hard to press, but I snipped the latch tab off mine so it's easy to put the connector back for any
"compliance" purpose that comes up, and pull it again later.
_H*
