It can't send a signal if it has no power. Try disconnecting the IGN wire instead.
I searched through the FAQs for something like this but came up empty-handed. I have a M4-ATX PSU powered up on my workbench and for some reason it's not sending the shutdown signal when I kill the power. Luckily I wok at an electronics manufacturing company, so I have a transistorized adjustable linear power supply (TALPS) to play with. Currently I have it hooked up like this:
The TALPS is set at 13v, connected to power and ground on the M4. I have a jumper wire from the IGN terminal to the +12V terminal on the M4. I also have the "thump" harness connected from pins 6/7 on the M4 to the on/off headers on the motherboard. I have dip switch 1 on the power supply ON so it will delay 5 seconds before powering on, and wait 1 min after the ignition is off before turning off the 5vsb rail.
Everything seems to be working fine until I kill the power. I turn it on, it waits 5 seconds, starts the computer and it boots fine. When I kill the power, it isn't sending the shutdown signal. It just turns off like I killed the power on a normal ATX power supply. The instructions for the M4 don't tell me crap, so I'm at a bit of a loss.
Any ideas why it wouldn't be sending the shutdown signal?
its sounds like you have your ign wire and constant power mixed up....
or you may have the jumper setting in the wrong place. check and double check those things...
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