98 xj
replaced master power window/ power door locks. Everything worked for 6 months. Power locks started to work intermitently. When inop you could hear a relay? clicking. Now no power locks

 

It it will be the solder joints on one of the master switches driver or passenger side. Maybe the fuse but then I'm not sure if the relay would click.

 

As weird as it sounds, at least to me, my understanding is the passenger side switch operates the locks.
Sounds like I was having the same problem as you.
My locks in my '00 would work 98% of the time. When they did not I would hear a click coming from the passenger side.
When they did not work it would only last for a short period of time. Stop to go in a store, they would not work, come out 15 minutes later, and they would..
One time they did not work for about 3 days though. This went on for years.
One day I decided to see if I could fix it.
Having extra parts I took a passenger side switch apart thinking I would try to solder it like guys do to the driver's side one.

You can solder what you see in the picture but I really wanted to get underneath and solder the connections where
the relay goes into the board. Problem was I could not really figure out how to get at it without destroying the switch.
Seemed to me that the board was glued to the plastic.
So I threw in another used switch I had. Lasted about a month before they would not work one day again
Threw in another used switch. Thinking that was 2 years ago and have not seen the problem since.
Yet. LOL.

 

How did you go about removing the switches from the clear plastic pieces? Like you I took my extra switches apart to investigate and went in from the back. I didn't have to deal with glue, just six screws and the clips on the plastic housing. When trying to remove the switch caps I broke a couple and deformed the plastic piece that protrudes and gave them a peak that would be uncomfortable on your finger. Also, from my understanding it is very possible that the wires going through the driver door boot have probably broken. Does anyone know what color insulation the power lock power wire will have in a '99 and/or '01?

 

You talking about getting the black cap off so you can separate the housing to get at the circuit board?
I have gently been using a door panel tool. Getting at it from underneath.
But even then pretty sure I have broken or deformed a cap or two.

 

​​​​​Yes, that is what I was wondering. I've heard the door panel tool before and I was thinking I'll try repairing my switches for free by soldering but if I ruin them I'll have to settle for buying new ones.