Love ’em or Hate ’em, Fuses Are Your Friend!

In 1992 Jon Spurlin, the DOA Technical Director, approached Stephen Wynne, then co-owner and Senior Technical advisor of DeLorean One, to provide a list of the top technical questions posed by DeLorean owners of the day. Not surprising, questions about the fused circuits at the fuse box ranked number two in the list. The rest of this great Tech Notes article can be found in DeLorean World Volume 9 #2.

We all know that fuses help prevent car fires when an electrical component experiences a problem. This is when the ‘Fuse is our friend’. For some reason, Fuses blow at the least opportune time – and they don’t feel like friends at that moment, but we must always remember – a blown fuse is our chance to fix a problem we can’t see.

This Tech Note addresses a related and increasingly common problem…

Fuse Box Melt Down!

One of the most alarming experiences for a DeLorean owner, is the sight of a fuse box with one or more fuse positions melted and burnt. Often the fuse itself is also deformed. 

Shown here at fuse #7 is a perfect example, but also notice the 20A fuse 3 spaces below has started to deform from heat.

Fuse Box melt downs result from excessive heat build-up at the junction between the female contacts in the fuse box, and the fuse blades. But how does this happen? Aren’t fuses designed to prevent this very thing?! Actually, fuses are designed to ‘blow’ when they experience too much current, but they have no ability to ‘blow’ in the presence of too much heat.

Y­­­ears of exposure to normal changes in humidity result in surface oxidation on most metallic surfaces. Surface oxidation means increased electrical resistance in a wired circuit. So, as the fuse box contacts and fuse blades become oxidized (even though there is very little space between them), the increased resistance of the circuit eventually generates sufficient heat to melt and burn the fuse box.

Maintenance of the fuse box and fuses is the simplest solution, and can easily be done at home. All of the contacts in the fuse box should be cleaned annually (even every 2 to 3 years is better than never!) The fuse blades should also be cleaned (or better, replaced) at the same time. Simply remove each fuse, one at a time, wire brush, file or sand both to bare metal, and re-install the fuse. Also, leaving the fuse box lid ajar or completely off will allow heat to dissipate more easily. There is rarely a problem of too much current it’s usually just too much heat!

 

With LED fuses available, replacing the fuses is an interesting option. These fuses, called ‘Indicator Fuses’, makes locating the ‘blown’ fuse easy! When the fuse ‘blows’, current in the wire stops, and the LED turns on – which means a quick and easy fix.

Often, if the circuit still ‘sort of works’, the most expedient (and inexpensive) fix is to jump past the affected positions with external, ‘inline’ fuse. Just be sure to use a fuse of the same rating.

In the case of a severely damaged fuse box, you may want to consider replacing it. Although you will be proud of the finished repair, this is not for the faint of heart. DMC offers a new reproduction fuse box (P/N 106913) that has better quality terminals for longer life and a modern plastic housing material that is rated to a higher temperature. There are reports of people finishing the fuse box replacement in 4 hours, while other people take several days to make sure it is done without error – but most people say it’s best to take out the passenger seat to make the work area accessible.

Take a moment to clean these critical components of your amazing DeLorean! It will save you the frustration of a ‘blown’ fuse when you’re trying to have fun! Below this paragraph, you’ll find a handy fuse box chart and a list of the fused circuits for a stock DeLorean as originally published in DeLorean World Volume 9 #2.

Please patronize my information resources for this article: DMC Knowledge Base at www.DeLorean.com and DMC#10515 at www.DMC10515.com

Cheers,

Gordon Carpenter, DOA Membership Director