Jeep Repair: power door locks, grand cherokee, door switch

Question
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Followup To
Question -
The power door locks on my 95 Grand Cherokee will only work to unlock the doors, they will not lock. This is true for both front door locks.  What are the usual causes of this?  Thanks in advance for your help.
Answer -
Bad switches!

All of them at the same time? It seems unusual that all the switches will unlock but not lock.  Is there some type of relay (located where?), or something in the computer that would cause all of the switches to act this way.  Thanks again!

Answer
I would start by replacing the driver's door switch, the one that locks all the doors at the same time. You also might was a broken wire in the driver's door harness, it's common since this is the door that opens and closes the most and bends the wires the most causing them to eventually break.