What goes wrong with license plate lights?
1. I can't register my 4Runner until I pass the
California DMV Brake & Lamp Inspection
2. I failed due to a few things, one of which was license plate lights
3. What normally goes wrong with the license plate lights & how did you debug?
a. I already replaced both bulbs with brand new Sylvania T194 bulbs
b. All fuses are good in the engine bay & under the driver side left dash
c. All outside lights work, including the tail lamps
The license plate light almost certainly is wired to the tail lamp wires so it's not surprising that the fuses are good.
Either the license plate light ground is bad or the license plate light power is bad.
But when I checked power from each lead to the license plate screw, there was nothing.
Likewise when I checked the resistance between the license plate screw and the two leads, there was 700Kohms (which makes no sense unless it's just a terrible ground point.)
It's really hard to find a good ground within the three feet of the leads of a DMM though.
(It's parked around the block so in the morning I'll wire a ground from the battery to test again because those results are strange.)
I need to debug from the point that the license plate light wires branch off the tail lamp wires to the bulbs (which are in parallel) and then to ground.
Have you ever had to debug the license plate lights?
Do you have any idea WHERE the wires meet the tail lamp wires?
In the door perhaps?
Do I access that junction of the tail lamp wires to the license plate wires from the outside or by removing the door inside trim?
Or is that junction of the tail lamp wires and license plate wires NOT in the door but in the interior of the 4Runner somehow?
Any hints to focus my debugging efforts would be appreciated as these little bulbs are holding up my registration.