Put a fuse box in the engine bay? Instead of multiple inline fuses.

[anthony1956]

As will be apparent from techtalk/kr500-new-loom-quiz I (which is to say with one of our number who is driving to Switzerland to give me hand - thank you!) am about to replace my K Series Year 2000 R500 Engine loom, because the wiring, or more accurately all the connectors are failing one after the other (six breakdowns in a row, all failed connector based), and the solution often is to cut out long lengths of loom wiring (especially with the fuel pump) by a simple addition of a fused flying lead having cut the wire for the original failed circuit. 

As a result I have a snake pit of fused wires in the battery area, because these on-the-road type solutions always default to taking 12v direct from the battery, because we know it will work. The most recent for example was a fused wire from the battery to the the inertia switch cutting out the fuse box fuse which circuit (not the fuse) failed in an unknown location (maybe one day I will find why), then the inertia switch connector failed (it simply fell apart with age) so that wire was joined to the inertia exit wire; all this cut out miles of wire all of which from my current day with an old car point fo view, all represents exposure to risk of failure and more work to find the points of failure.

Long story short (I know, too late) I am thinking ONE wire from the battery with a nice 12v supply to a fuse box mounted say back to back with the one in the footwell, but inside the engine bay, next to the inertia switch would allow me to tidy the snake pit and formalise the roadside repairs. Also would avoid the back wrenching twist required to get at the original fuse box which I dread. Basically I want anything engine related fused in the engine bay, my back demands it - which also restricts the use of the progressively older MAIN wiring loom to instruments and lights and makes the engine component circuits easy to inspect. 

If I forgot to ask a question it is what fuse boxes best serve this purpose ? 

Anthony

[revilla]

I've got one that would be fine on my engine test trolley. As you know I've just sold the engine, so it's no longer needed. Good as new - you can have it if you want?

[anthony1956]

yes please.

[revilla]

I'll add it to the list. Will send you a picture when I get home.

[SM25T]

You know my 4-way one from CBS. Sure they do one with more fuses.

[anthony1956]

they do, but I can't cope with the variety! :-)

[anthony1956]

https://www.amazon.co.uk/KKmoon-Blade-Holder-Warning-Marine/dp/B01IVRC9RA

Looks as if it might do what I want, bus-bar and the LEDs are a bonus. Not sure about the damp-proofing.

And as someone reminded me, I should be taking the 12v feed from AFTER the cut-off switch, not direct from the battery which so doing cuts out the cut-out which is not the idea. 

Anthony

[7 wonders of the world]

Dont think it has a bus bar as standard though you could make one with a loop feed or split feed battery direct and ign fed.

[anthony1956]

I've ordered one of these: bus bar fuse box

[7 wonders of the world]

Must have mis copied my link first time..!

Nice box,

Assuming all your loads have the same power feed requirement..?

 

[SLR No.77]

Why don’t you just renew the faulty parts and take it back to original ... they’re pretty reliable.

Stu.

[anthony1956]

hi Stu, several reasons I will attempt to gather here:

(1) I desire to no longer have to keep bending and twisting and then looking up, to see my fuses, then hurting my fingers getting the fuses out to check them... etc, you get the picture. 

(2) I am replacing the old engine loom with a new shiny (really it is!) one. This is standard, except my new Brise alternator has it's own 4 wire loom. I'll leave the standard bits in place, but insulated/unconnected in case of future need.

(3) 2 above means I am not replacing the "Main loom" (no longer available), which has been responsible for five of the preceding six breakdowns. The exception is the most recent one being the alternator B+ broke at the connector, mostly, but appeared connected because of its covering. There seem to me to be two fundamental aspects in play, the engine bay and all components necessary to keep it running and "everything else", such as lights, instruments and .. can't think of anything else off hand. All the breakdowns have been failures of connectors, some more obvious than others. These long runs mean more connectors, which as I say are currently what fail - with one possible exception.

(4) The Main loom has long runs of wires simply to get to the fuse box, which as you read at (1) above I dislike intensely. No more are the days when I would happily lie upside down with my head under the dash while using my hands to work on something... Anyway, point here is heat soak. The R500 K generates a LOT of heat and fries everything, not least swmbo's feet. Frying times do vary of course and over the years I have replaced wires and added high temperature sleeving in places, though not enough places I now realise. Here's this point, the long wire runs in (3) mean all those wires are heat soak fried over time, they become stiff (reduced voltage), even if they still work time is against them, some call it bad luck, but I see it coming. Specifically this is all the loom wires that cross the bulkhead inside the engine bay, just behind the dry sump tower (itself a source of heat).  One of the failures MAY have been heat soaked wire, but I can't find the fault. In past years I have suffered breakdowns form heat soaked wires, years ago I wrote many screeds about the click of death and how to solve  or pre-empt it's multiple causes, now lost in the blatchat switchover.

So it seems sensible and suits me to me to have engine related matters managed from the engine bay, given most of these now all have flying fused lead power sources in any case, as solutions to each of the connector failures. And using a fuse box with LEDs that light up on fuse failure is a bonus. Using a bus saves many wires to the battery (which will be corrected to downwind of the cut-off).

Therefore I don't like the standard design, it causes and has caused me too much grief and I want something accessible, easy to manage and robust (not multiply vulnerable). And having re-read your question I can add that I disagree about them being pretty reliable. Not in my experience they aren't. It occurs to me that many owners own their car for short periods (less than 18 years) and may see one problem or another, but not all of them to provide a longer term view. 

All of which reminds me the ECU fuse is in the cockpit fuse box. That now makes me very nervous.

All wires to this new box will be led further way from the engine, not sure how yet.. 

@7 Wonders 

Power, I guess you mean current since volts is always 12.. so yes the box does have an overall current limit, 150 amps I think, so I'll have to monitor that. But no, individual components can have varying current requirements as long as the bus and more importantly (since this bit is down to my wire choice) the feed wire which will have to be of the same ilk as the cut-out circuit. Is that somewhere around what you mean?

 

edit: it may sound odd, but down all the years I have always viewed my R500 as reliable. Sometimes it just needs extra attention and to be understood as having certain special needs because of heat and vibration and these days add the passage of many years. 2006 was a bad year (click of death) and now 2018 has been bad. I once had the alternator fail, outside the very Italian factory that manufactured it! It was a weekend of course. There was the clutch release arm that failed, but Minister had let me down there and I was real "unhappy" about that as it turned out it was a known weakness. So over 18 years that's not so bad in my book. Maybe my bad memory is a good thing.

Anthony

 

 

[SLR No.77]

Anthony, from my own experience I have to disagree that the route you are taking is better than keeping nearer to standard. I bought my SLR in 2007, it's a 1999 car and over the previous 8 years it had been heavily modified  by previous owners (1900cc, 244bhp) and electrically messed with - the Rover engine loom no longer existed as such. In the first couple of years of my ownership I had repeated electrical failures, all related to messed with electrics which left me stranded a number of times.

Then following an engine failure in 2010 I took the opportunity to completely re-create the engine loom as original with only carefully planned additions that fitted in with the "design" of the o/e loom, e.g. additional LT feed to run a twin coil pack to go distributorless at some point in the future, low oil pressure warning light feed etc. In doing this I sourced the correct colour cable from Polvolt so that the wiring now conforms with the o/e Caterham wiring diagram to make any future fault finding straightforward.

I also added an additional relay to the underdash relay stack to solve the K-click issue, this I wired in such that the only break point into the original loom (my new loom) was the feed out of the MFU, there's now a male/female 6mm connector into which the new relay cable is connected ... and the wiring to the additional relay is now routed with the main loom under the dash which dispels the myth that the K-Series click has anything to do with long cable runs.

All the connections were made with the correct connectors and tools keeping it o/e, again with a view that faults would be easy to trace, my poor experience with electrical problems in this car (which I had none of in my previous Caterham) meant reliability had to be at the top of the list. 

Since doing the work in 2010/11 electrical gremlins have been non-existent. Your concerns regarding getting under the dash to change fuses should be unfounded, I've not been there since doing the work ... no fuse problems, no relay problems, no dodgy connectors. And yes there's plenty of heat in my engine bay - I don't have the primaries wrapped. The wiring now conforms to the wiring diagram but it's not been needed!

Just my two-penneth :)

Stu.

[anthony1956]

Hi Stu,

That's an interesting read. 

I've never heard anything about long cable runs being anything to do with the cod/k-click, or anything else. I don't want them in my car when they are to take engine components feeds via the fuse box in the cockpit. edit: why? I suppose the many hours spent trying to trace faults that would have been easy with short visible cable runs; as well as bulk-head wire frying. I like things where I can see them. 

My failures are related to age, heat, vibration, not a modified loom - in fact the opposite, an unmodified loom. 

I agree about using the correct colour coding which I will be endeavouring to do. 

My brand new engine loom will remain standard except for having the Emerald and the Brise both of which have non standard wiring. I am not modifying my engine loom, but I am making sure that parts of it that interface with and go through the Main loom, no longer do so. Except the fuel pump feed to the pump and the associated earth. 

For the 18 year old Main loom I will be moving the fuse box (i.e. then having two fuse boxes) for engine components in to the engine bay to stop heat soak into those wires and to remove as many connections as I can, and make it all visible. Bear in mind when I say "moving", most of these items are already on flying lead inline fuses around the battery already, so a proper bus bar fuse box is just tidying up the existing reality.

All the connections will be made with the correct connectors and tools. 

The K Click issue isn't just one issue, it's several, but here isn't really for that well oiled discussion. I remember the (excellent) relay mod was presented as the only requirement to avoid the click.

Like yours my relay mod breaks the feed in one place only, though yours sounds neat whereas mine isn't. I don't want my starter circuit going via the main loom any more than necessary and definitely not in the cockpit. 

Your re-made loom is ten years younger than mine (granted I am not clear if you replaced the wiring, but it's the connections that are the main issue). Put another way mine is nearly twice as old as yours. Mine was fitted in 2000 and yours in 2010/11 . Ten years ago mine was all fine and dandy. So mine as it is, has lasted twice as long as yours. I was thinking your car doesn't generate as much heat, but that BHP would suggest otherwise, then I note your wires are half as old. Check them for stiffness, esp the D+ to the alternator gets missed. A lot of this may be related to the shape of the primaries, if you have 10cm or more gap to any wire the problems are significantly less.

My concerns about going under the dash remain. I find them well founded. I can count my fuse/relay failures on one hand, but whenever there is any issue, the first step is check the fuses. In this case inspection is the issue, not failures. I want them where I can see them and some LEDs to boot sound like just the ticket, forewarning every time I take the bonnet off, which is very frequent for oil checks every two minutes.

Thanks for focussing my thoughts. :-)

Anthony

 

 

 

[SLR No.77]

I can see your reasoning. Whichever way you decide to do it, bear in mind that the engine bay and especially the engine side of the bulkhead and heater tray will get pretty wet in a downpour, the underdash area will remain dry. I've mounted my emerald on the three posts as per original MEMS, I've seen aftermarket installed ECU's fill with water when the heater tray gets flooded and they've not been mounted in an elevated position. IIRC the o/e R500 ecu is mounted flat on the heater tray without any weather protection, my guess is it's substantially more waterproof than the others.

Stu.

[anthony1956]

Yes, damp. Something I have under consideration owing to said bag of spanners. Yes the MBE was on the heater tray, which drains on to my legs rather than flooding. So is the Emerald, so I should evaluate that position. You remind me of the FB tour when a member broke down because a relay was fitted upside down in this area, and filled with water. Still amazes me he diagnosed and fixed it, but illustrates the wet that can ingress there.

Anthony

[rj]

Stu,

No problem to troubleshoot a custom loom if it's well documented. If it was I'd never be able to do my next loom. (In fact as long as you put effort into getting the colours right it makes everything a lot easier).

One benefit from shortening the wires is that you can actually drop a few kgs, which matters, especially to honour the Superlight spirit.

[anthony1956]

'cos they're not reliable like I said (or at the least implied) before, I think where we differ is the passage of time.. And another thing, I want easy roadside diagnostics and fixes. I much agree about waterproofing. Thinking hard about that.

edit: here's a thing; there is a fault (0 volts no continuity) in the yellow/green between the inertia switch and the fuse box. I have no idea where and run out of ways to search, given the wire is buried inside the Main loom, which I am not about to dismantle. Hence "shorting" that circuit with an inline fuse. That was before the inertia switch connect also failed (literally fell apart with age etc) so shorted that circuit too pending parts which await at Redline pending their general rescue package shortly. This is the only instance where it may in fact be an actual wire that has failed and not a connector; however, experience so far indicates IF there is a connector in there somewhere, that is likely to be the culprit. 

I think except the inertia switch (econoseal) and alternator (B+ ring terminal) the failed connects are each spade terminals. It feels like many, but on reflection probably just a few, but one is bad. The first was the purple wire power feed, which is still disconnected, that one I may probably replace with the new loom version. I think I need to sit by the car and write some notes. What was, what is and what I'd like to be. Getting rid of the purple wire spade connection is a certainty.

I can't help wondering what we will find when we take the existing loom to bits - like finding where purple wire's fault is - the connector caused two break downs.

Ant 

[Tony Whitley]

Get rid of the fuse box (so last century!) and do the job properly with a Life Racing PDU-10.

Not cheap mind you.  In fact, eye-wateringly expensive

[anthony1956]

it certainly is! I think I'll just add a bit of lecky tape as extra sealant.

[rj]

For some reason all PDUs are horrendously expensive. Never understood why. 

[7 wonders of the world]

My original loom is in the corner of the garage.......my previous car which I built form a kit had more loom related problems than I care to remember, dry joints, badly fitting pins, endless redundant cable taped back - pretty shocking really.

So when I rebuild my current car I started with rolls of thin wall cable, bags of connectors small fuse box and fused relays, and a couple of rolls of Tessa tape.

Once you draw out what you need its reasonably straight forward, my car is totally LED no wipers, screen heater etc front indicators are integral with headlights.

Started making a front loom and rear loom with the cables loose under the dash (scuttle off) then made the Emerald and engine loom, then the remaining loom, key loads have individually fused relays, headlight, fuel pump cooling fan etc, remaking items have feeds from fuse box either constant (side lights) or ign feed as required.