1990 Silverado, 5 wire door locks

Hello! I have a 1990 Chevy Silverado K1500 2dr truck. I have a 5 wire relay system for my door locks which were working great until the other day. It will unlock the doors, but it wont lock them now. I went back into the relay wiring and checked the lock relay. I unhooked the alarm wire input, which is the negative trigger on my Compustar alarm, and grounded it to the truck and it sparks like there is a short or something. When I connected these relays on installation, the relay would lock when I touched the trigger wire of the relay to ground on the truck. Now it just sparks! I have tried swapping the relays. Same problem. I have replaced both relays. Same problem. Any ideas out there??

Anybody have any ideas?

hey there i dont know if you know this but chevy trucks are positive trigger lock and unlock any questions on how to do this email me at Teamsolow_37

2 door models are 5 wire and 4 door models are (+) trigger.The output for the locks should rest at 12 volts but go to ground when activated by the remote. If your having troubles with the CPU, go back to the place that you bought it from and have them look at the installation and have it replaced. You have a lifetime warranty on the system if it was installed by an authorized dealer. Jeff

Velocity Custom Home Theater

Mobile Audio/Video Specialist

Morden, Manitoba CANADA

So you think the alarm CPU maybe giving me the problem?