I have a 1998 F150 and when I bought it, it came with an alarm system. The brand is Karr. When I activate the alarm the locks go down fine. When I deactivate the alarm the door locks do not unlock but the alarm is disabled. Is there any way to fix this? Thanks in advance.

 

I just had this problem too. The power locks seemed to have enough juice to lock the doors but not enough to unlock. It eventually progressed till it would do neither.

Replaced both lock solenoids with parts from Rockauto.com and now everything works fine.