I have an 01 Bonneville SE and have had problems with the interior lamp fuse. The interior lamp fuse would blow intermittently. Sometimes a new fuse would last a week or two and other times it would blow the next day. I switched out the relay and the problem seemed to go away. After several weeks the problem came back. The fuse now blows immediately every time I plugged a new one in. I tried a 15amp fuse instead of the 10amp and it no longer blows the fuse immediately (at least for the last week). I have checked all bulbs and ohmed out all wires for connectivity. What else can I try? What would make the current increase to blow the 10amp fuse? Any ideas would be great.

Sounds like you have a intermittent short. This will be hard to find with a multimeter. Using a higher rated fuse you are risking a fire. You will need to inspect as much as you can.

possible grounding issue... check the grounds and clean them too

have you made any mods to the car lately? stereo, switches, anything that could be shorting out

Can you elaborate on exactly what you did when you "ohmed out all wires for connectivity"? While it is possible a poor ground could in theory cause this to occur, this is an extremely unlikely scenario in the 2K+ Bonneville. Grounding has been accomplished quite differently than in pre-2K Bonnevilles. This sounds more like a short to ground, not a poor ground connection.

You had what sounds like a probable intermittent short to ground causing the fuse to blow. Probably, replacing the relay was a coincidental interim solution. Your intermittent problem sounds like it'* now become permanent. Although frustrating, this is actually a good thing. Finding a constant short is almost always easier than finding one that'* intermittent.

As previously asked, are there any aftermarket additions or modifications? Anything that'* changed recently? If you replaced the relay and it seemed to temporarily fix the problem, look very closely at all the wiring underneath the rear seat. Check for any pinched wires or sections of harness. Screws that may be penetrating the wiring harness, etc. These are things that may have been shifted while you replaced the relay causing a "temporary fix". There is wiring running underneath the back seat that is all part of the interior lighting circuit.

Just to clarify, all the instrument panel backlighting is okay?

By ohming out the connections I meant that I made sure that I had 12 volts at the proper terminals at the rear fuse box and checked the wiring for shorts in the wires. I also ran through a relay test procedure that I found online and everything checked out.

I have no aftermarket mods.

The 15 amp fuse that I had used for interior lighting blew today.

The instrument panel lighting is fine and when the fuse is working all interior lights are operational.

Is there an easy way to test whether a wire is shorted to ground other than through inspection?

I will inspect the wiring underneath the back seat and around the fuse box. I have had the seat out many times recently working on the interior lighting and to troubleshoot/replace the battery. It may be possible that a wire got pinched. I will let you know what I find.

If you've been working around the seats. That'* a good place to start. You may have something pinched. Try to follow the wires looking for anything that might be pinched.

Can you please post the specific relay you tested and the procedure you followed so I can better understand what you've already done?

Interior lighting wiring is very widespread throughout the car. I am going to suggest you try and isolate where the problem is. The first item to eliminate from the equation is all the overhead wiring (partly because it'* the easiest). This includes the reading and map lights. To do this, you can unplug the headliner wiring harness from the main body harness. Remove the trim panel covering the LEFT 'C' pillar. There is a Lever Lock style connector at the base of the 'C' pillar. Unplug this and see if you notice any change. I would strongly recommend reverting back to 10A fuses. This will eliminate a short to ground in the vanity lights (we've seen problems here before) and less likely, the overhead courtesy and reading lights.

If this fails to reveal the problem, we can continue from here.

I have an 02 SLE. My interior light fuse would also blow, next day or next week. Talking with the dealer indicated a known problem with the sun visors (they also have lights in them). I played with them and finally got the fuse to blow. Changed both visors and haven't blown a fuse in almost 2 years. You might try unplugging the visors first to see if that works.

Keith Z.

This would work as well. There are advantages and disadvantages to both approaches. I usually divide the car into more broad sections to start. Generally the roof and headliner, left half of the body and right half of the body. I'll isolate each region and then leave it disconnected until such time as I narrow down where the problem is. By using this approach, some of the really difficult problems can be found a little easier by knowing that the wiring is physically disconnected and there is no further need to check that section of harness.

I do suspect that if the problem is in the headliner it is most likely internal to one of the sun visors. This would only make good sense because there is wiring that is flexed every time the visor is moved.

I went back to the 10amp fuses.

The short is back to intermittent. The relay test I performed was at this link www.autoshop101.com/forms/hweb2.pdf. I performed the continuity check and the operation check with voltmeter. Just to make sure about the relay, I swapped it with another identical relay and the fuse still blew.

I will visually inspect around the back seat for pinched wires and will remove the rear fuse box to look at the wires. I also am going to disconnect the connector in the pillar to disconnect overhead lighting. Since the short is now intermittent, I believe that I am just waiting for it to blow again. Before I disconnect the wiring, I flexed the visors several times to try to cause the short and blown fuse. I was unsuccessful. I will let you know what I find.