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The following write-up addresses an issue with the OEM Fog Light switch on our XJs. This may apply to you if your Fog Lights won't work despite the following:
Bulbs have been inspected and are good
Fuse Relay is good
There are no visible wiring issues/corrosion near the Fog Light assembly
The switch was “touchy” for a while before finally failing
The problem with the OEM Fog Light switch is that the internal contacts get corroded, creating electrical resistance and eventually a bad switch. Additionally, these switches were designed for infrequent use and thus can overheat fairly easily, damaging the internal components. There are two light bulbs in the switch - one to illuminate the switch itself (has a gel cover) and another that serves as the “on” indicator, which does not have a gel cover. The indicator light gives of a significant amount of heat and sits in the center of the switch. This is what causes the overheating. Both issues will be addressed and resolved in this write up:
-Phillips Head Screwdriver
-Petroleum Based Solvent (ex. WD-40, etc.)
- Q-Tips (2)
Remove the plastic trip that covers the radio, climate control and switches (there are no screws, so give it a little elbow grease and it should pop right out. Set this aside.
With the console trip/cover taken off, remove the three screws that attach the switch board to the dashboard. Once the screws are out pull the switchboard away to expose the wiring harness.
Disconnect and remove the switch from the switchboard.
To open up the switch to clean it you will first want to remove the two bulbs from the housing. There is one on the top of the switch and one on the bottom. Remove these by using your thumb to unscrew (they are not in tight) and set aside.
There are two clips that hold the switch in place – the switch slides right out. You will notice that some of the components are warped from heat damaging the plastic. This is caused by the indicator light. The switch will still operate fine with moderate melting, so don’t get discouraged!
Note the corrosion in the switch housing – clean this using a Q Tip and some WD-40 (or equivalent).
Also clean and remove the metal piece from the switch and gently stretch the spring out by a few milimeters or so. This will compensate for normal spring wear and extend the life of the switch by ensuring strong contact/connection.
Now put everything back together, but DO NOT REINSTALL THE INDICATOR LIGHT BULB (the one without a gel cover that site on top of the switch) to prevent future overheating.