Uploaded April 2026 | Updated September 2026, 2 weeks ago
These ELM 327 vehicle diagnostics modules are widely available online, and have very different functionality based on the quality of the software. The name comes from the company who wrote the original software (ELM Electronics), but were unfortunately ripped off. In doing so they have kinda become an iconic company, and have made vehicle diagnostic equipment much more available to the masses.
The bluetooth password for these devices is usually 1234 but can also sometimes be 0000.
I swapped the ISO standards in my colour coded pinout, The CANbus is ISO15765-4 and the K/L line is ISO9141.
This unit was a bit trickier to reverse engineer than usual, as it has cut corners by implementing a CANbus network driver with discrete components, but it's also a good thing as it lets you understand what would effectively be hidden by a dedicated driver chip.
But there's a flaw. At some point in the design/copying/manufacture it appears that a PNP transistor has been used where there should have been an NPN transistor, and that has a huge impact on the ability of the CANbus section to work. If the software hasn't been equally hobbled then the fix is easy - just replacing that transistor with an NPN one with the industry standard pad pinout.
This unit should still work with the older K/L-line network though, so it should still work on some older vehicles. I'm not sure how many vehicles use multiple types of network. I'd expect them to use just one of the three available on the port.
The dongles firmware only deals with communication with the vehicle's computer systems, and a phone or tablet via bluetooth. The work of interpreting the data is done by a suitable app. One of the most famous being Torque. It's absolutely worth getting the paid version of the app as it is very capable and has clearly taken a lot of time and effort to create. It's only $5 for the Torque Pro app.
Note that something like this can't compete with the diagnostic equipment used by professional garages for the deeper diagnostics, but it can definitely help point you in the direction of technical issues. The garage equipment usually carries a massive price tag and ongoing subscriptions to updates that only make sense if you are earning money full time in that trade.
There are different versions of these dongles with different software, and some can access more parameters than others.
This one came from AliExpress, but they are available from lots of sources with a wide price range and functionality.
If you want one of these to experiment with then here's a link to the item on AliExpress (not a sponsor).
This is an affiliate link, but that will not affect the price you pay.
https://s.click.aliexpress.com/e/_c4Sbyo2b
Supporting the channel with a dollar or two on Patreon helps keep it independent of YouTube's quirks, avoids intrusive mid-video adverts, gives early access, bonus footage and regular quiet Patreon live streams.
patreon.com/bigclive
Alternatively, for a single coffee contribution you can use PayPal:-
paypal.com/paypalme/bigclive
#ElectronicsCreators
These ELM 327 vehicle diagnostics modules are widely available online, and have very different functionality based on the quality of the software. The name comes from the company who wrote the original software (ELM Electronics), but were unfortunately ripped off. In doing so they have kinda become an iconic company, and have made vehicle diagnostic equipment much more available to the masses.
The bluetooth password for these devices is usually 1234 but can also sometimes be 0000.
I swapped the ISO standards in my colour coded pinout, The CANbus is ISO15765-4 and the K/L line is ISO9141.
This unit was a bit trickier to reverse engineer than usual, as it has cut corners by implementing a CANbus network driver with discrete components, but it's also a good thing as it lets you understand what would effectively be hidden by a dedicated driver chip.
But there's a flaw. At some point in the design/copying/manufacture it appears that a PNP transistor has been used where there should have been an NPN transistor, and that has a huge impact on the ability of the CANbus section to work. If the software hasn't been equally hobbled then the fix is easy - just replacing that transistor with an NPN one with the industry standard pad pinout.
This unit should still work with the older K/L-line network though, so it should still work on some older vehicles. I'm not sure how many vehicles use multiple types of network. I'd expect them to use just one of the three available on the port.
The dongles firmware only deals with communication with the vehicle's computer systems, and a phone or tablet via bluetooth. The work of interpreting the data is done by a suitable app. One of the most famous being Torque. It's absolutely worth getting the paid version of the app as it is very capable and has clearly taken a lot of time and effort to create. It's only $5 for the Torque Pro app.
Note that something like this can't compete with the diagnostic equipment used by professional garages for the deeper diagnostics, but it can definitely help point you in the direction of technical issues. The garage equipment usually carries a massive price tag and ongoing subscriptions to updates that only make sense if you are earning money full time in that trade.
There are different versions of these dongles with different software, and some can access more parameters than others.
This one came from AliExpress, but they are available from lots of sources with a wide price range and functionality.
If you want one of these to experiment with then here's a link to the item on AliExpress (not a sponsor).
This is an affiliate link, but that will not affect the price you pay.
https://s.click.aliexpress.com/e/_c4Sbyo2b
Supporting the channel with a dollar or two on Patreon helps keep it independent of YouTube's quirks, avoids intrusive mid-video adverts, gives early access, bonus footage and regular quiet Patreon live streams.
patreon.com/bigclive
Alternatively, for a single coffee contribution you can use PayPal:-
paypal.com/paypalme/bigclive
#ElectronicsCreators
