I've had the HDC warning lamp on intermittently since I've owned my 2000 Disco II. I was getting these 2 codes. So I set out to replace my interior passenger fusebox.

101:Brake Light Relay Drive Short to Supply

081:Brake Light Relay Short to Supply


I traced every connector, every wire per the diagrams. The wires and connections all checked out OK --and the fault points to a problem with the "HDC relay/brake lamp relay" which is integral to the passenger compartment fuse panel. Ie - not replaceable.
Check out what I found in my fusebox (from sunroofs leaking, which I've corrected). OUCH










BTW for 99-02, the interior fusebox part #'s that work are YQE103320 -> YQE103830 -> YQE000110 -> YQE000250 -> YQE000410. NOT YQE000251 which is off 03/04.

I was able to buy a replacement fusebox YQE000250 off an 01 truck off ebay for cheap that looked good, albeit a roll of the dice. The fusebox on my 2000 had a 1999 date stamp and was the oldest of the 5 valid part #'s in the range.



After researching with the wiring diagrams, I think the HDC / brake lamp nonreplaceable relay is *maybe* the small one labelled NEC JAPAN on the back, bottom left of the 4 relays(?). But not 100% sure. Very tough to figure out. And it's clear to me that the relay may be bad but the reason it went bad would have been the corroded circuit board (and the relay may not be bad after all!).



I prised it all apart to see if I could fix the bad fusebox but decided it was hosed.Everything works perfectly now, no more intermittent HDC warning lamp.

A few more reference pics of the work in process that may help someone.



Bad fusebox

ooh cool the mysterious amazing IDM






The rear connections

DO NOT SHUT THE DRIVERS door with this panel down...will crack something (either the panel or the door speaker pocket)

Safety first-battery neg disconnected!

One final point: when you replace the fusebox, which contains the IDM (Intelligent Driver Module(?)) that is pictured above, there is some re-sync process that happens between BCU and the fusebox's IDM when you reconnect the battery.. It's automatic, there is no intervention or Nanocom required. In my case, the Disco wouldn't start, I got a bunch of flashing lights/security system weirdness, and general odd behavior. At first I thought I had a bad (new/used) fusebox or I'd mistakenly not seated a connector. While I was looking at diagrams, it seemed to all fix itself. After about 10 mins, everything worked. So there's that . PS online I read "leave the ignition on for 10 mins" or "turn the key this way" -- I turned off the ignition off and went inside to my laptop, so I'd believe this re-sync process happens irrespective of the key / ignition status once you connect the battery and turn the ignition on.

 

Hi there fellow PDX Disco Owner! Thank you so much for this post. I'm chasing down some of my own Amigos issues, and the occasional solo HDC Warning Light is the most common of them. I really, really appreciate how thorough this post is and the photographs provided. I'm getting the same codes you were getting with the HDC light on. I'll have to go out and check my own fuse box for corrosion.

I've already done the Option B fix, which has fixed most of my Three Amigos codes. When I was in there I found all of the insulation to both Shuttle Valve Switches had crumbled away and left both wires bare.

Again, this post is great. Thank you.

 

HEYO! I am so glad it helped. I wished I had this when I was doing mine so... !

 

+1, Nice write up!

 

Great job!

 

Follow question regarding the Fuse Box part numbers. My 2000 Disco has SAI. I see a couple compatible fuseboxes on eBay, but they are listed as coming out of Non-SAI trucks. Do you know if they would still be compatible?

 

I don’t think it matters. The SAI pump uses fuselink FL2 and relay R6.

 

You can see water issues on steel reinforcement just above fuse box. So, replacing fuse box may have repaired issue. But, it will most likely happen again...unless...water infiltration issue is addressed.

Excellent write up and pictures, though.

 

YES, I fixed the water leaks... !

 

Well, as mentioned above I had the same problem with a Brake Light Relay shorted to the supply. I sourced an appropriate fuse box off of ebay and installed it. It's been a little over a month since then and I have not had any instances of the HDC amber warning light appearing. Before the fusebox swap I got it maybe 30% of the time I drove the Disco. Thanks @nashvegas for doing the legwork on this!

Now I just need to exorcise my occasional outlet valve shorts and I should have the Amigos pretty much squared away.