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2020 Chevy Bolt LT
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38 Posts
Discussion Starter #21
I'm thinking the second speaker got added into the 2020 model year, but it's def not part of the 2017. I have a copy of the 2017 and a shitty copy of 2020 service manuals. 2020 references the Front/Rear speakers as P48F and P48R, the 2017 manual only references P48 in front of the vehicle as you mention. See below for a screenshot of the same schematic I pasted for the 2020 as found in the 2017 manual.

Though now that I look at it again and compare to the 2017 schematic below, I realize I've misinterpreted the schematic in the beginning. The module itself doesn't actuate any relay in response to gear fwd/rev, BCM is doing that, and the PASCM & relay are just tied to the same ground point. I totally ignored the whole BCM blotch in schematic :oops:

2017 pedestrian alert sound control module schematic here:
30490


I'm less sure now what differences exist between 2017, 2018-2019, and 2020 control modules, and I still have no part number for the 2020 馃拃

Oh well, the CAN bus Pi hat I wanted came back in stock the other day, so I ordered one, picked up a 2017 module, part # 42547472 off ebay, some Delphi Micro 0.64 terminals, and female harness connectors for now to start off poking around with.
I'd still like a 2020 to match my own car for funzies, but maybe if ever I have something to swap in-place, I could pull my own later and analyze for functionality differences?
 

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2 goals:
  • Jetsons car sound instead of the existing ethereal sound.
  • Additional horns for gentle notifications.

I'm going to go at this another way. No CAN bus. No Arduino or Raspberry Pi. Just simple Adafruit. Runs WAV or OGG files. 20w amplifier.

Buttons for the additional horns but the GND trigger for the pedestrian sound will be voltage based via a relay(?). Additionally, I plan to have a power button instead of the train horn for constant sound. Inspired by this video

My part list:
鈥 Adafruit Audio FX Mini Sound Board - WAV/OGG Trigger 16MB Flash $20 Adafruit Audio FX Mini Sound Board - WAV/OGG Trigger 16MB Flash
鈥 Stereo 20W Class D Audio Amplifier - MAX9744 $20 Stereo 20W Class D Audio Amplifier - MAX9744 spec sheet MAX9744 20W Stereo Class D Speaker Amplifier with Volume Control - Maxim Integrated
鈥 Factory Pedestrian speakers or PA Speaker 8ohm 25w $15 Amazon.com: All-Weather Mono Trumpet Horn Speaker - 5鈥 Portable PA Speaker with 8 Ohms Impedance & 25 Watts Peak Power - 180 Degree Swiveling Adjustable Bracket for Easy Maneuverability - Pyle PSP8: Car Electronics
鈥 Green power button $8 Amazon.com: ESUPPORT 16mm 12V 3A Car Green LED Light Power Metal Push Button Toggle Switch Socket Plug Latching Black Shell: Automotive/
鈥 Red horn button $8 Amazon.com: ESUPPORT 12V Car Auto Red LED Light Momentary Speaker Horn Push Button Metal Toggle Switch 19mm: Automotive/
鈥 Green horn button $8 https://www.amazon.com/gp/product/B0748DWRW4/
鈥 Hard wired 12v -> 5v power converter $12 https://smile.amazon.com/dp/B00BMIVFK8/
鈥 Add a fuse wire adapter $9 https://www.amazon.com/10-Pack-Add-circuit-Adapter/dp/B01DYQM6EO/

Thoughts?

Anyone know the impedance of the speakers? I have a 2020 LT with 2 speakers.
 

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2020 Chevy Bolt LT
Joined
38 Posts
Discussion Starter #25
I just reached out to, and got word from GM Parts Direct, the 2020 model year pedestrian alert sound control module part number is 42731430, $67.90. Ofc I'm gonna buy it, for my experiments.

As yet I still haven't setup my test bench due to lack of motivation during a global pandemic and better things to do at work, but I'm gonna order the part anyway and hope I get around to it sooner rather than later :)

re: speaker impedance, I'd be interested to know this too if anyone pulled theirs already and can check with their multimeter, but since I'm attacking the concept from the opposite direction I won't get around to working with the real speakers right away 馃槄
 

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2017 Premier, Arctic Blue - Oct 2020
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66 Posts

This is the sound i want, is the intro starting and looping, before the vox enter. :eek:D
 

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4 Posts
I'm thinking the second speaker got added into the 2020 model year, but it's def not part of the 2017. I have a copy of the 2017 and a shitty copy of 2020 service manuals. 2020 references the Front/Rear speakers as P48F and P48R, the 2017 manual only references P48 in front of the vehicle as you mention. See below for a screenshot of the same schematic I pasted for the 2020 as found in the 2017 manual.

Though now that I look at it again and compare to the 2017 schematic below, I realize I've misinterpreted the schematic in the beginning. The module itself doesn't actuate any relay in response to gear fwd/rev, BCM is doing that, and the PASCM & relay are just tied to the same ground point. I totally ignored the whole BCM blotch in schematic :oops:

2017 pedestrian alert sound control module schematic here:
View attachment 30490

I'm less sure now what differences exist between 2017, 2018-2019, and 2020 control modules, and I still have no part number for the 2020 馃拃

Oh well, the CAN bus Pi hat I wanted came back in stock the other day, so I ordered one, picked up a 2017 module, part # 42547472 off ebay, some Delphi Micro 0.64 terminals, and female harness connectors for now to start off poking around with.
I'd still like a 2020 to match my own car for funzies, but maybe if ever I have something to swap in-place, I could pull my own later and analyze for functionality differences?
I鈥檓 actually working on this project. I鈥檝e ordered an audio indicator that can be programmed with a 30 second clip that will repeat itself as long as voltage is present. The schematic you posted looks pretty simple.
 

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2020 Chevy Bolt LT
Joined
38 Posts
Discussion Starter #28
I鈥檓 actually working on this project. I鈥檝e ordered an audio indicator that can be programmed with a 30 second clip that will repeat itself as long as voltage is present. The schematic you posted looks pretty simple.
Nice! I'm glad this research helped, as I've only bought the parts going into endless projects throughout this pandemic but never found the motivation to actually start doing anything... I'm excited to see what you come up with!
 
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