pcmhacking.net

I am getting errors trying to connect to my PCM for the first time. Here's what I have done so far.
Ordered OBDX Pro using the link provided on this site.
I'm using a Dell Latitude e5430 laptop with windows 10, 2 usb ports and a 15 pin serial port
Downloaded PCM Hammer 021.2 from this site.
Read the faq section on this site. Watched a few different youtube videos on setting it up.
Got a 2005 PCM from a Avalanche with flex fuel vin z.
Made a bench harness using a plug/transformer with 12v 1A output. Tested it with my voltmeter and it was putting out 13.8-14 volts and to verify which side is power/ground.
Connected the ground to pin 1 on the PCM and pins 4&5 on the odb port. Connected the power to pins 19&20 (installed a switch on 19) and then to 16 on odb port. Confirmed switch is on.
Connected purple wire on pin 58 pcm to pin 2 on odb port.
I hooked up the ODBX Pro using the supplied usb cord to my laptop. Initially I got unable to connect to com 5 error, then found that I need to hook up the odbx to my laptop, then to the pcm and then power it on. Then start pcm hammer. After doing this it gives this error once I select "Read Properties"
[12:00:02:198] PCM Hammer 021.2
[12:00:02:211] Friday, June 13 2025 @12:00:02:21
[12:00:02:844] Device Found: OBDX Pro VX
[12:00:02:885] Device Successfully Initialized and Ready
[12:00:07:583] VIN query failed: Timeout
I also did a search on this forum and found a post where someone suggested going into device manager, selected hidden items, selected ports (com and something else??) and then right click to delete. Then restarted computed and started all over again.
Anyways, please let me know if I'm missing something. It's late and I have been reading and searching for a several hours. I appreciate the help.

The interface is working. Check your bench wiring, pins, power and ignition signal to the PCM.

I will go through the harness and make sure all the connections are tight. I'll try plugging the pins directly to the pcm. I am using the aluminum block with the plastic pin cube as it came from the factory. I made the harness prior to ordering the obbx. I appreciate the reply.

Blue or green connector?
Might try pin 59 for data as well, that works as well..
There's another battery feed and ign feed but I don't believe they are needed.

I'll try later tonight just plugging the pins directly in without the aluminum/plastic block. If it doesn't work I'll try pin 59. I don't remember what wires were where. I just pulled them all out and started fresh using schematics from others. I watched a few videos where everyone used the pins I mentioned above. The only difference was some didn't bother with a switch on 19 and others did as sometimes you have to cycle the ignition off when reading/writing. I know I had to do that when I tuned my truck with a diablopredator, so I figured it wouldn't hurt. Thank you for the reply.

Try as per the image here. It works for all PCMs with this type of connector. viewtopic.php?p=92138#p92138

If your confident about the wiring and connections try another power supply or a car battery. Some power supplies are electrically noisy and cause problems. Battery is clean power. If it works with battery then either always use battery or source another power supply.

You dont need ignition switch to flash but you do to change vin as the change is written to flash in the seconds after ignition off and that doesnt happen when you power the whole thing off together