I post primarily in the X308 section but, I’ve worked on a ton of X100’s as well as other jags. However, this post applies to all the X100/X103 vehicles as well. I’m just trying to make you all aware so we can continue to preserve these beautiful cars for many years to come.

I’ve had 3 different customers with an X100/X308 variants come in with potential alternator issues within the past 6 weeks. I always start by the visual inspection of the alternator, starter, bulkhead connector on the P/S, mega fuses in trunk and battery. It’s becoming increasingly common that the mega fuses in the trunk are getting loose and causing concern for a fire. Vibration, added electrical load and deteriorating braided battery cables are most of the issues related with the mega fuses burning up due to added resistance. Years ago I had a car get towed in because there was no power from anywhere when turning the key on. The issue I found was a bolt on the backside of the mega fuse holder got so hot that it melted out of place and grounded against the spare tire well that it was bolted to and charred the metal in that area. I’ve seen blankets, shop towels and other flammables around the spare tire before and a risk of fire was always high if this were to happen. I *highly recommend* taking a 10mm, 13mm wrench and 20 minutes of your time to disconnect your battery, removing all cables at the mega fuse holder (take a picture with your phone of the cable orientation) that’s located to the left of the battery just ahead of the spare tire. There’s 2 10mm nuts that hold the mega fuse holder to the body. Once that’s off, take the 2 mega fuses out, gently but firmly tighten the 13mm nuts that holds the bolts to the fuse holder. If the fuses themselves are not charred, you can take a fine grit sandpaper or wire brush to clean any corrosion off. After you reinstall the fuses, gently but firmly tighten the nuts that hold them inside the holder. Reinstall the fuse holder in the trunk and battery cables.

 

 

Great stuff! Thank you for the information. I will be sure to check that on mine. I haven’t read reports of issues with these on the X100 but it may just be a matter of time.

 

It’s kinda like a spare tire, it’s out of sight and mind until it’s needed.

 

Good info - thanks!

 

Thank you for this. I have periodically checked the tightness of the mega fuse block's exterior bracket bolts with a socket wrench while installing a new battery in the trunk, but I have never disassembled that fuse block to the point where your photos show it.

 

OK, dumb question: after disconnecting the battery, how does the mega fuse cover come off? Is it just a snap-on cover? I can’t tell from burying my head in the trunk, but I’m old and mostly confused! The exterior of my cover looks pristine if that’s any indication of the health of the fuses. No sign of stress/duress on the 4 wires going to and from the block.