GM MDI Clone problem.
Posted: Thu Aug 12, 2021 5:38 am
Hi everyone.. I happened to see a gm clone MDI on aliexpress with wifi for just under $128 and decided to roll the dice.. I have a few clones already and my genuine MDI bit the dust after many years, it gets old fast remembering to bring it home, then bring it to work,etc so I gambled on this one..
Anyways.. it has a problem.. Pin 2 vpw fails.. It can read or sniff messages, or if you use the Data Bus Diagnostic Tool you can look at the voltages like an oscilloscope and it does see voltages and can see modules on the bus.. Problem is whenever it tries to send it fails.. With nothing on the bus you can see a little tiny rise in voltage, 0.00 volts to 0.010 volts, maybe.. Such a minimal change it damn near looks like noise except it only shows up as jitters when I try to send a command, I'll try to remember to get a pic if anyone wants to see it.. This makes me think it's making an attempt but the circuit that raises the voltage is messed up.
In any case my question is has anyone repaired one of these? specifically for the vpw write circuit? I'm assuming it uses some sort of transistor to raise the 'talk' voltage and that would either be missing or broken or the resistors/diodes/fuses,etc are also absent or broken.. Hopefully it's just a bad solder joint, these aren't exactly excellent examples of soldering and assembly, lol..
I do have another clone to take apart and compare, that will be my first task, maybe tonight or maybe sometime this weekend but I thought I'd throw this out to you guys and see if anyone's been there already..
Anyways.. it has a problem.. Pin 2 vpw fails.. It can read or sniff messages, or if you use the Data Bus Diagnostic Tool you can look at the voltages like an oscilloscope and it does see voltages and can see modules on the bus.. Problem is whenever it tries to send it fails.. With nothing on the bus you can see a little tiny rise in voltage, 0.00 volts to 0.010 volts, maybe.. Such a minimal change it damn near looks like noise except it only shows up as jitters when I try to send a command, I'll try to remember to get a pic if anyone wants to see it.. This makes me think it's making an attempt but the circuit that raises the voltage is messed up.
In any case my question is has anyone repaired one of these? specifically for the vpw write circuit? I'm assuming it uses some sort of transistor to raise the 'talk' voltage and that would either be missing or broken or the resistors/diodes/fuses,etc are also absent or broken.. Hopefully it's just a bad solder joint, these aren't exactly excellent examples of soldering and assembly, lol..
I do have another clone to take apart and compare, that will be my first task, maybe tonight or maybe sometime this weekend but I thought I'd throw this out to you guys and see if anyone's been there already..