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Doug, ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 8608
Experience:  Mitsubishi employed and Factory trained ASE certified technician
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I have a 2002 Montero Sport. The rear cargo dome light will

Customer Question

I have a 2002 Montero Sport. The rear cargo dome light will not turn on. I pulled out the unit and connected a tester light and I am not getting power. All other interior lights work perfect. What am I missing?
Submitted: 1 year ago.
Category: Mitsubishi
Expert:  Doug replied 1 year ago.


All other interior lights.... the dome light and map lights all work fine?

When you checked for power at the rear cargo light did you check directly on the harness on the red/black wire and with a good solid ground?

Customer: replied 1 year ago.
Map lights, door lights and the dome light between the front and rear seats all work perfectly. When I removed the light in the rear checked off the red and black wires. Rear gate sets off the "open door" light on the dash and the front dome comes on but still no power to the rear cargo dome.
Expert:  Doug replied 1 year ago.

I don't really see any expectation here but a broken wire somewhere in the mix. Looking at the wiring diagram the power supply is a direct line from the same source for all of the interior lights without even any connectors in between or anything.
If you don't have 12V on the red/black wire, its going to be a long day or tracing wiring for a break.

Expert:  Doug replied 1 year ago.

It looks like there is one splice point you might be a little suspicious of, let me see if I can get a location on it

Expert:  Doug replied 1 year ago.

Yep, looks like we have splice S139 above/behind the drivers shoulder to worry about.... that is the point where the 12V to the dome lamp splits off to send 12V to the rear cargo lamp. That would be your only weak point to focus on since there are no connectors to be loose/corroded/etc.

Expert:  Doug replied 1 year ago.

What I would probably do at this point knowing the dome light works but the cargo lamp definitely does not have 12V would be to pop the trims off the driver side of the head liner and open up the harness there and see if I can find anything going on with the splice (it will be a bundle of tape that is hard in the harness). If the splice seems OK, then I would check it for voltage immediately after it leading rearward... if there is no voltage, I would make a new splice point; if there is voltage, then I would continue rearward in the vehicle until I found the point where voltage drops off preventing it from reaching the cargo lamp.
Again the 12V source is your critical indicator... if there is no 12V on red/black at the lamp, we know the problem is in between there.

Customer: replied 1 year ago.
Ok will start pulling down the headliner and looking. At this point of the harness in line does not have 12v then it will have to wait till another day. Now should this light or short affect the clock or the in mirror compass to not turn off after the key is removed.
Expert:  Doug replied 1 year ago.

The lack of voltage to the cargo lamp should have no impact whatsoever on the clock or compass operation. Just like the schematic I attached, the power source is straight off an existing known-good (dome light) source, and has no further service after that point except the cargo lamp.
If you are having issues with the clock compass up top then that may indicate you have something going on in the roof there that affects more than one thing (for example if you had water getting in that may have damaged multiple wires), but as to the power supply to the cargo lamp breaching between the dome light and rearward, that would not affect any other items.

Expert:  Doug replied 1 year ago.

If you need further help with this just let me know.