Hey guys! Currently, we are working on another project on our Suburban. We haven’t had any working dome lights in this vehicle since we got it. I thought I would try tracing the power wires going to the dome lights and see what could be the problem. First off, when it comes to working on any electrical problem in any vehicle, you check the weakest point in the electrical system first.
The first item to check is always the fuses in the fuse box(s). These days on the newer vehicles there may be multiple boxes of fuses to check. So I started with the fuse box under the hood. This fuse box is the main power box to power most everything on the vehicle. I started checking each fuse with a test light for power on either side of each one. A 12-volt test light works the best. If you are not getting power out of one of your fuses from your tester, You may have to pull them out with a pair of needle-nosed pliers. If the test light shows that the test is good but you are still not getting power to that item then the best thing to do is to pull it and look at the condition of the fuse.
Look for any burnt marks on the contacts or if the filament looks good try testing it with a continuity tester for the best results. If there isn’t a power problem here then it could be another fuse in one of the other two fuse boxes. I turned my focus to one of the boxes that are at the end of the dashboard hidden by the left front door. In this fuse box, I looked to see which one was for the dome (or) interior lights. I’m still using my test light at this point I did find one bad fuse for our lights.
But, still, we have NO lights. Now I have to dig deeper. The next step in the process is to trace all wiring from the headliner dome lights to our fuse box and or body control module. Now we start down to the wire harness for the interior lights. First I started pulling down the window pillar located on the drive side first, wires existing underneath there, and testing for any voltage coming through them with my test light. This came back as a dead end because there was no power existing in these wires.
Next step I pull out my continuity tester to test small increments of the wire to be sure there isn’t a broken wire (dead space) anywhere inside the insulation of the harness that may be causing power loss. Using the continuity tool I tested from the window pillar to the dome light in the headliner. It showed a good current flow. Then I tested from my sun visor down to the body control module plug for my lights.
After reaching the body control module with the tester I had adequate flow from the harness plug to the sun visor so I moved on to the wires in the body control module to see why I’m not getting any power at that point. After looking at the cover I found other slots that weren’t being used but had power well suited for the dome lights. One of these slots said vanity on them so we used it.
Once I had this adapted, I tested my harness going up to the dome light in the headliner and we have POWER!!! My buddy I got this truck from was shocked to see dome lights in the ‘burb working since they had been out about 8 years.