(Intermittent) Dome Fuse Blowing
 

Hello,

I am looking for help to determine what causes my dome light fuse to blow. I have read some other posts for similar issues and troubleshooting. However, my problem is intermittent (2 days, 7 days, 3 weeks) and therefore cannot use the voltmeter to find a short. So, I would like to start isolating wiring bundles/components. I am hoping someone is familiar with the dome light circuit and where I can disconnect wire connectors for a couple weeks at a time (ex: is there an easy way to unplug the keyless entry/security ecu?/where).

Here's what I know:
1. If I put in a new 10A fuse everything will work (keyless entry, dome and courtesy lights).
2. Problem doesn't affect the radio as others have reported with their issues.
3. I checked the visor lights doesn't seem to be the issue.
4. I thought it had something to do with rain, but then it blew after being dry for a while.
5. It can blow the fuse while the car is sitting after being locked at night. In other words, something happening while the car sits locked... for example, I locked the car one night using the remote. Car beeped it's normal "I'm locked". Next morning,remote unlock didn't work, had to unlock with key, fuse was blown. I have locked/unlocked the car using the remote to try and reproduce the problem to no avail.

Please let me know your thoughts. It would be so much easier if it had a dead short. Argh!

2003 V8 Sport 2WD

Get the wiring schematic out and start isolating circuits. For instance, pull the dome light or pull the connector that tells the door it's open. This will slowly point you to the problem area.

I don't have the schematic in front of me so I can't offer more details at the moment.

Hi. Unfortunately, this is easier said than done. I have looked at the wiring schematic. I was hoping that someone is familiar enough with the wiring they can tell me the location of the plugs for each branch of the circuit...because it is tied into so many things. Also, if I take one bulb out at a time, it will literally take 1 year to figure this out. I need to narrow this down to a specific part of the circuit and then further isolate from there. For example, is there an easy to access plug somewhere that feeds power to the alarm/keyless entry module (which I think is in the rear pillar)? Is there a plug that powers all the components in the headliner/overhead area? Etc.

Dome light is tied into body ECU, Courtesy lighting, dome lighting, alarm and interacts via relay with other components.

take the dome and map lights out and check the contacts. might have just touch the body panel. if you need to take out the dome assembly and map lights assembly and check for body contact. also did you switch to leds?
loose wire for the visor can cause this too. you can take it out and confirm, only a few screws.

Yes, I checked the visor. Dome lights have been turned off for a while. I think it may be the dome relay. The other night I went out to wiggle wires under the dash and doors, play with remote, etc. At one point the fuse blew again, but I wasn't touching anything (both front doors were open). I put in a new fuse... Bam! Fuse blew. Went to Oriellys in a different vehicle to buy package of 25 fuses and two new 194 bulbs for the doors. Tried to put new fuse in, blew immediately. Then another and another blew. Then it took one. Replaced both door light bulbs. It was okay for a couple days but blew fuse again. Going to order new dome relay and try that.

anything installed in the truck? aftermarket alarm? aftermarket led bulbs inside?

Attachment 342338
do this test

Hi riceandpho,

Thank you. The link you sent is a great way to test for a dead short. However, I don't have a constant dead short which is making this difficult to figure out. I don't know for sure if I am getting a short or drawing too much power. At this point I am leaning toward the latter. I think I have a faulty body ecu or alarm ecu that is causing an overcurrent. I looked at the wiring diagrams and the dome fuse powers interior lighting and the key less entry/alarm module. I was asking about where some plugs are that could isolate the circuit. But, there really aren't any connectors that only have the lighting circuits. For example, the wire bundle that feeds the overhead lighting also feeds the side curtain air bags. I did replace the dome relay and that wasn't the problem. I am going disconnect the alarm module next and see how that goes - again, the problem can occur when the car is sitting and parked. So, I think it is most likely something that happens after the lock button is pressed on the remote - which then triggers the dome monitoring and the timer for all the lighting through the body ECU. I do have an aftermarket stereo but it is hooked up well and was also replaced in the midst of having this problem (for unrelated reasons). All the bulbs are standard. I haven't seen on any diagram where the radio could cause the dome fuse to blow although that seems to come up in some other threads.

on aftermarket radio, you might have used the wrong dimmer wire, its the orange, i would just cap that off. some use orange as positive and theres a orange negative.

aftermarket alarm, check how the dome wire is hooked up, its a ground signal, not a positive signal.

If it powers interior lighting why not pull all the bulbs and see if it still pops?

If it doesn't put one by one back.

At least you can eliminate the bulbs. I don't have a wiring diagram so cant help.

*edit
Well I found a wiring diagram see if I can find anything

Update on What I have tried to no avail. In no particular order:

1. Unplugged the keyless entry module in the rear pillar.
2. Left the two dome lights turned off.
3. Replaced the dome relay.
3. Replaced front door courtesy bulbs.
4. Exercised door switches repeatedly.
5. Inspected trunk hatch wiring.
6. Inspected visor wires and and exercised them.
7. Wiggled wires under the dash, engine compartment, tailgate, doors, etc.
8. Unplugging the backseat stereo controller thing.

The only clue: It happens after shutting the doors and/or locking the car either using the remote or manually. In other words, I notice the fuse has blown again when I return to the car and open the doors (at night) or turn the car on (or start it) and the gauges are all wacky and clock is reset again. The only exception to this was one instance where I experienced a dead short when replacing the fuse after messing with bulbs and wires (as mentioned above. That was prior to replacing the relay btw).

What I will try next:
1. Unplug all the door courtesy lights; then remove visors if not the courtesy lights. I really don't think these are the problem but it is a good suggestion and I will give it a try next.

Thanks,
Ugh.

SOLVED (mostly)
 

Well, I found the problem...
1. I was able to isolate the alarm module and that did not solve the problem.
2. I was able to isolate the keyless entry system and that was not the problem
3. I replaced the Body ECU just for fun ($80) and that wasn't the problem.
4. I removed all of the interior dome circuit bulbs, still not the problem.
4.1 I replaced the interior lights with LED bulb kit from Amazon just for fun. They offer plenty of illumination, pretty sweet.
5. I removed the both visors completely. THE FUSE STOPPED BLOWING AFTER I DID THIS. YES, FINALLY!.
5.1 I tested the visors out of the truck for shorts and no matter what you do (hit them, wiggle them, etc.) they won't test bad.
5.2 I eventually put both visors back in and they haven't blown the fuse...yet. I suspect when I was messing with them out of the truck it moved the wires enough so that it's not shorting at the moment. I had them out of the car for a couple weeks and didn't blow the fuse, so I am confident it is one of the visors. I suppose it could have been one of the visor sockets and re-installation of the mirrors moved something, but that is unlikely due to all the movement available to the visor.

:usa2:

Update: still good to go!

I'll try your solution as I've done everything else you've tried. Here's my thread:

Dome light fuse blowing intermittently