What could be wrong with a power lock on a 2003 Jeep Liberty that does not work even though the fuse is okay?

Answer 1

Lots of possibilities, switch, actuator, connectors, relay... Unfortunately you'll just need to get a wiring diagram and go through the whole troubleshooting process. You can usually get a little help from the dealer, but don't expect them to spend much time with you. Usually it's just copying some pages out of the shop manual, and even then they only do that for you if you're nice to them. Good luck. ==Expanded Answer== A wiring diagram is nice to have but not necessary as it does not genrally tell you HOW to troubleshoot. The key is knowing what the components are, what they look like, and how they work and interact with each other. A wiring diagram does not do that, and EVEN SERVICE MANUALs are sometimes inadequate in providing photos or sketches allowing one to know what he's looking for and where it may be located. I guess they assume that the user already knows all the basics. You said that the "fuse is okay." You did not say HOW you determined that. Fuses can be deceiving when VISUALLY trying to acertain whether they are good or bad. Some fuses which are open [will not carry current] can look perfectly normal. This occurence is not especially common, but it does happen. Visual determination really only works to CONFIRM a "blown" fuse, which by the way indicates that a short circuit occured [that's what causes fuses to blow], AND SUGGESTS a potentially serious fire hazard problem. Do NOT ever replace a blown fuse without first troubleshooting the affected circuit for the source of the short which caused the fuse to blow. Then CORRECT the fault BEFORE replacing the fuse. And NEVER use tin foil, or a "jumper" in place of the fuse, or an "oversized" fuse. All of these "cheaters" will probably result in overheating of the wiring, and a fire! To truly confirm that a fuse is good is to check it for continuity with a METER, or with a battery powered TEST LIGHT. If the meter, set for Ohms, indicates current flow [NOT a zero reading], or if a powered test light turns on, THEN the fuse can be concluded to be good. If either or both of these show the fuse to be open, even though it "looks good," it is NOT good! Also, you used the singular term, "...a power lock...that does not work..." I cannot tell from your question if you mean the power lock "system" which is singular, even though there are two door lock assemblies, or if you mean ONE of the two door locks is not working. That distinction makes a big difference in the analysis of the failure. IF BOTH of the door locks are not working [assuming a KNOWN good fuse], then that condition suggests an OPEN circuit[for example, a connector pulled apart]between the fuse and the master switch cluster(usually on the driver's door), or a defective master switch assembly]. If, however, one door lock is working, and one is not, that condition suggests the problem is in the master switch for that door, or the wiring harness, or the actuator, or the acutator ground connection. You do not necessarily need a wiring diagram, IF you understand enough to identify the parts described above, and to "trace" the wiring/harness from point to point looking for a cut, "parted," or burned component. Basically, with any such system, the wires run from the fuse block to the master switch cluster[wherever it is], and then to the doors having the power lock acutators. Troubleshooting means visually checking for obvious failures, and using some test equipment and elimination procedures to identify the fault. It is not really that difficult, but neither is it easy. And, it is certainly tedious and possibly time consuming!