I have a 99 XJ 4x4. Whoever I try to unlock the doors, either with the switches inside or with the key fob, they wont lock or unlock. You can hear them making noise, but no action. This goes for all the doors except the back hatch door. It locks and unlocks. Where should I start?. Thanks

start with one door (PS front), take the door card off..see whats going on. Have a test light, multimeter and FSM with circuit diagram on hand. Report your results

If they all make a noise, but wont work, that would suggest there is a voltage drop, meaning they cant get enough current to fully actuaute

So, the power locks system can be a nightmare. I spent many hours last summer diagnosing the locks on my Jeep for a very similar issue. Mine would intermittently click instead of lock, but sometimes would work fine.

The best advice I can give you is get a year specific factory service manual (FSM) which has all the wiring diagrams, properly color coded, and get to work. There is definitely a learning curve to diagnosing electrical problems but with the correct tools you can learn how to navigate between the manual and your Jeep pretty efficiently and narrow problems down to specific circuits.

I ended up finding a connector by the driver’s kick panel that was corroded and would intermittently lose continuity when it was handled. That fixed my problem for a short period of time. What finally fixed my locks issue for good was reflowing the solder on the circuit board in my door. Kinda wild because there were no visible cracks but I felt as if I had tried everything else at that point. Sure as poop, it worked.

The locks system is tied into several other systems (on my 99, at least). For example, you cannot lock the doors when the driver’s door is open. The system is connected to the door switch plunger. IIRC, there’s also something tied into the ignition cylinder, or maybe it was the headlights? Can’t really remember. I think the connector that was corroded was the door switch circuit.

[QUOTE=Justin Jackson;3560717 Where should I start?. Thanks[/QUOTE]

I add to my advice, maybe try the kick panels first, easier access

* search the archives..TONS of posts on similar issues

* find forum poster Cruiser54 website..some material you need is there

Solder reflow in switches fixed my problem.
Youtube it.

Just did another yesterday for a power window problem.
The factory solder gets old and brittle.