791xv lock problems

Hello,

I've had this alarm in my 02 Ford F250 for about a year now. Just yesterday, I noticed that when I arm my truck, I hear them try to lock but don't. They make noise, but don't lock. The locks sound sluggish. I can use my power lock switch and they lock and unlock just fine. Any suggestions?

Vehicles with keyless entry, the lock wire is simple negative trigger. A ground problem would cause problems. If you send a ground into the green or blue lock wires exiting the 791 and the locks work, then add relays.

If it's not keyless entry then it's 5 wire reversal and relays should have been used. Sometimes they're incorrectly interpreted as positive trigger by the installer and blow the lock/unlock transistors in the 791.

so just add a relay to directly ground the lock wire?

thanks for the help

Yup.

Sometimes the ground will have resistance over time and cause a voltage drop to the point where the lock output is not really sending a true ground. In a worse case scenario, you can always add relays to boost the ground out of the security system.