Hello all,

I'm new to the forum and have a 2004 Disco 2 that's not starting. I was driving and heard a strange sound under hood, a 'sizzling' sound like something was melting. It lasted less than a minute then went away so I kept going to my destination a few miles away. An hour later, when I went to leave, the truck wouldn't start. Lights, dash lights, etc. all come on but I only got one click that sounded in the firewall somewhere on passenger side, about where BCU lives. No crank, nothing. New starter, new alternator, year-old battery putting out 12.8 volts according to multimeter. Tried the screwdriver across the terminals of starter and the solenoid spins. Had it towed home and it now sits in the driveway where it's been for over a month.

I found no evidence of anything 'melted' in the engine compartment or in firewall behind interior glove box and don't have any idea what produced that sound I heard while driving. When I looked at fuse box in engine compartment, I noticed that the 30 amp fusible link labeled 'SM' was blown. I replaced it with another 30 amp FL and it blew again. A short somewhere, but where, I can't tell. Then I removed fusebox from engine compartment and could not see any visible damage. Cleaned battery connections to fuse box, ground leads, etc. Pulled 'SM' relay and bench tested it and it worked.

Is it possible the fuse box in the engine compartment has gone bad inside? I removed the functional piece of the box from its plastic container and can see no damage to the conducting circuitry on the bottom. But this thing has sandwich layers and I don't want to yank it apart any farther. Anybody have any experience with this sort of thing? Is it worth replacing this fuse box with a used unit? I have a hunch this might be what made the 'melting' sound I heard but I don't know how to confirm that without possibly destroying it by taking it apart further.

Thanks in advance for anyone who might have some insight here. I'm okay with turning wrenches and scraping my knuckles but this electrical voodoo has me flummoxed.

 

Which fuseable link is blown? They are numbered, 1 thru 13, SM does not compute. It must be FL12, starter relay fuse. Other four 30 amp wouldn't affect starting. Sounds like you have a direct short to ground, l'd check harness running down to starter, there are several areas that become damaged with age...especially along alternator bracket and cooling tube.

 

Thanks for that! Hadn't thought about that end of the harness, but it makes sense there could be damage, intrusion of oil, water, etc. And yes, it is FL-13 that keeps blowing (..I've attached pic of inside fuse box cover, where I saw the 'SM' piece in big letters before the 'FL-13' - my old eyes!..) Should I be more concerned with connection points as opposed to a short within the bundle? I ask because the bundle of wires is sheathed in that flexible black plastic housing where you can't see the individual wires. I didn't suspect a short in one of the individual wires inside because of that plastic housing, but I suppose I should?

Inside cover of engine compartment fuse box for '04 Disco 2

 

Odd, normally F12 is starter motor fuse, according to Land Rover Discovery Electrical download. Anyhow, SM would represent starter motor...so F13 would be your main issue. Since you already pulled engine compartment fuse box, which would have been my first thought too, since l've had issues with wires rubbing underneath on inner fender metal. And you see nothing, so l'd be looking at the harness and large cable that runs from battery to starter, etc.

From fuseable link, current runs to relay (R2 starter relay) then to starter motor through harness. Try pulling the relay and installing new fuseable link...if it blows, then short is between fuse and relay inside fuse box...if it doesn't...short is down stream somewhere in harness.

 

Thanks again, Deputy! This is a a HUGE help in trying to zero in on the culprit here. I'll try your suggestion re: pulling relay, and see if this doesn't narrow it down and report back with the results. If it turns out to be the fuse box, I'm guessing I'll have to find a used replacement online.

 

I'm speculating a bit here as I've not had your specific problem. I'd check that wiring harness that runs vertically up and down that's "zip-tied" ... where these red arrows are. These harnesses deteriorate in this area and if you see bare wires (give it a jiggle, move things around, see if your plastic wire conduit is gone). This could be where your short to ground is (if not the underwood fusebox etc). I see a ton of cars in the salvage yards with very poor / damaged harnesses in this area.

 

Thanks for the insight. Yep, I took a quick look at those harnesses tonight and they do look kind of shaky. Especially that little bundle you pointed out in the second photo unsheathed from the black plastic housing - mine were coated with grime. Looks like I'm going to have to get in there and disconnect what I can for a better look. Gotta be one of those harnesses or that under-the-hood fuse box. I'll test the box as the Deputy suggested and if it's good, then time to start disconnecting and pulling what I can of the harnesses. Will report what I find. Thanks again!

 

I had this exact same issue on the harness where nashvegas showed in the pictures. I had a wire to the starter solenoid that got melted on the exhaust manifold and blew the FL13 fuse.

 

Thanks Robert. Funny you should cite that wire that clips onto the solenoid of the starter as I noticed the same thing myself. The insulation was melted in one spot where it must've come in contact with the exhaust manifold or something else.

It was one of the first things I found when digging into this, and thought it might be the issue. So, I bypassed that wire by running a new one from the starter solenoid to the fuse box, connecting it to the same pin the original wire ran to (mine was brown with an orange stripe, I believe). That didn't fix the problem and the fusible link for the starter, FL-13, still kept blowing.

Unless that original wire had some internal splice in the harness that I can't see, it seems this should've worked. In theory at least. Since it didn't, I guess I'm still looking at fuse box or harness issue.

 

I didn’t bypass it, I just taped it to prevent any further shorting and then replaced the fuse. It sounds like you’re on the right track though.