Adding 520T & 507M to Clifford 570.6X

You got this reading while the system was armed? That's the only output that is GWA, so you don't have any outputs the same as it. Must have exceeded the (-)500mA rating or spiked it and fried something internally.

Yes, I put the DMM leads on H1/1 and H1/6. Unarmed it was reading 0.1v and when I armed it it read between 0.4v and 0.5v. Not sure if I did this correctly, but H1/1 reads +12v when grounded to the vehicle.

Then the NPN Switch has failed on the board. You got 2 choices fix it or replace the brain if you don't want to live without it. If there still using the same package as the 18 PIN version of the 5701 viper it will look similar to this. And will be connected to the main ground plane on the bottom of the board. I don't have any newer units to look at in case the are using a SMD package or not in the newer units. IF your going to test it disconnect it from all wires and then open it up by removing the 4 screws on the bottom corners. You can check it like a diode for continuity. The legs connected to ground and GWA Should test Open or high resistance with probes both ways. And the Non ground pin should only test 1 way to each of the Ground and GWA legs.

Here is the NPN on a 5701, it will usually be close to the GWA output pin.

Wow. Thank you so much for all the useful information, Lurch. I certainly would not have been able to figure this out on my own. I'll try to get this fixed this weekend sometime, not sure if I'll replace the part or the whole brain, but I'll post back to let you know how everything turns out.

Ok No Problem.