Pondering a little lighting modification.
Are the front fog lights driven by a relay or a mosfet in the BECM?
If its by mosfet, does the BECM recognise when a bulb is blown, or does it just remain blissfully ignorant of the condition of the front fogs?
Probably from a mosfet but they don't have bulb monitoring. One of mine fills up with water so the bulb blows regularly but the dash never tells me, I have to use the traditional method of getting out and having a look.
This is what I found (let's see if this works)👍
Marty's back in the next few days, so once he's un-jetlagged himself he'll be able to give you the definitive answer to what switches the fogs...
Separately fed too... I didn't consider that, though I suppose if they meant to have bulb monitoring, that would make sense. Lack of monitoring makes it slightly easier for me though. I could have gone out and unplugged one to find out, but, surprise surprise, it's still raining.
They are MOSFET driven, yes. And they should have bulb monitoring on the circuit. Mine will tell me if one has blown...
Bit strange that Gilbertd's one doesn't throw up an error... Though some vehicles with a Low Line BECM (older ones) didn't have the fog light MOSFETS, and the wiring was added afterwards to control the fogs separately through a relay, which won't have lamp monitoring on them...
I am back now... yay.... o a different note.. noticed that the security LED isn't flashing on the RR anymore :( so I think that I'm going to be replacing the main battery! Will have to investigate that today... guess 9 weeks was too long for it, even with the MK3 receiver!
Welcome home Marty! <br>
Back to the welcoming embrace of your P38, which is obviously craving your attention as soon as you walk in the door.... <br>
Gilbertd's is an ex Police vehicle IIRC so might have a different wiring fit.
Orangebean wrote:
Gilbertd's is an ex Police vehicle IIRC so might have a different wiring fit.
Not sure if it's that different, I've taken most of the spurious extra cabling I found in it out. It's got a high line BeCM and no extra relays for the front fogs that I know of. Unless there's some extra wiring I haven't found yet so they could flash the front fogs along with the blues and twos.
Well I'd hoped to use a relay or two to wire the fog lights up to come on with main beam - when flashing or on constantly. I have done on other cars before (without any fancy monitoring) because it puts a bit more light on the ground, and because I can. I'd use a 5 pin relay to switch the feed to the lamp itself to a separately fused supply, with the relay coil triggered by the high beam wiring.
I suppose I could still use 5 pin relays on each lamp and I wouldn't get any nagging from the message centre unless the fog lights were actually turned on when I flashed / put main beam on, seeing as the monitoring only happens when the light in question is turned on. That said, does it monitor constantly, or only for a short period after turning the lamp on?
I wonder if the UK Police setting in the BECM disables the monitoring?
With police vehicles it's the same as policemen themselves: they are above the law...
Sloth crossposted by a few minutes.
Speaking of law, over here fogs only may be on in combination with dipped beam, if you wire them combined with high beam you will have a problem using them in case of... fog!
Whether BeCM only monitors dipped beam is easy to check, unplug the extra high beams and switch on, no message no monitoring.
I'm not worried about monitoring of the high beams - the fogs will be powered through a separate feed from the battery via a relay. But the load of the fogs presented to the BECM will appear to drop to nothing while my relays are energised, as if both bulbs had blown. It would just be annoying if, in actual fog, I then put the high beams on too, and the message centre beeped at me complaining my fogs had mysteriously both suddenly appeared to have blown, as my relays would energise switching the feed to the fog lamps from the BECM to a new feed...
In the UK, the last time I checked, highbeam was pretty much a free for all in terms of lighting. If high beams from the factory are going to cause significant glare to oncoming traffic, there isn't much point defining exactly how it does it. The fog lights will otherwise continue to function as they normally would on the button. If my MOT tester got funny, I'd just pull the fuse from the new feed and they would cease to come on with highbeams :)
I think I see what you are getting at. Using a 5 pin relay so with dip and the fogs on the feed to the fogs would be via the normally closed contact in the relay so would work as normal. When you switch to main beam, the relay would operate so the fogs would come on as auxiliary lights. It shouldn't cause a problem though because normally as soon as you switch to main beam, the supply to the fogs is cut so there would be no current to monitor anyway. You're right on the law. Dipped beam headlights must be no greater than a total of 110W (or the equivalent if the car has HIDs), front fogs may only be used with dipped beam as the theory is that if the fog is light enough that you can use main beam without blinding yourself with the glare, you don't need fog lights. But main beam is as much light as you can chuck out of the front as you like. There's no restrictions on number of lights or total Wattage.
Maybe turning off the bulb monitoring is another of those odd things that the Police spec setting in the BeCM does so they can wire the front fogs to flash along with all the other lights. It's never really bothered me to be honest, I've spent most of my life having to look at the reflection of my lights on the garage door or the back of another car to see if all the bulbs are working, that the monitoring is just a bonus (or, in the case of a dodgy front sidelight bulb holder, a pain in the arse, all that beeping to tell me a light I would never use on it's own isn't working).
That's what I'm after yes :)
Just been out to replace the mirror I managed to smash on the way home (narrow road, oncoming car, tree jumped out of nowhere) and played with the lights. On mine, with full/main beam on, the fogs stay on too.
I will unplug one at some point to see if the BECM notices. If it does, I can get around this with another relay. When the original fog feed is on, have the other relay disconnect my feed to the first relay coil from the main/full beam. Thus, when fogs are switched on via the button, operation of the full/main beam does not influence the source of the power to the fogs. That has the advantage of saving on contact wear in the relays I suppose - especially when flashing the lights. Which I suppose in fog you're unlikely to be doing, but hey.
A little bit overkill for a bit of light on the ground, but I have an abundance of relays, and its a bit of fun with zero cost.
Well, the battery was totally dead on the RR... showed 1.8V when I put a meter on it... so a new MF31-1000 should be delivered today, and I'll get that installed and see if the old girl actually still likes me when she starts up...
Re lamp monitoring... As far as I know (I will check though to be sure once I'm up and running again!) Police mode in the BECM does not change anything to do with the lamp monitoring on any of the circuits. I know that my BECM is set to 'Police' (was like that when I got it officer...) and again, pretty sure it tells me if a front fog lamp has blown...
In regard to your question Sloth, the monitoring is constant all the time - it's actually done off the status pin of the MOSFET, so if it is driving a lamp, and it then blows, then it the MOSFET will suddenly register no load on it, which will activate the lamp failure message. So if you have a separate relay operating the front fog lamps, then turning the fogs on from the switch will most likely throw an error up.
It's on the back burner at the moment, but I am looking at making a 'bypass' for the lamp monitoring to allow being able to use LED lamps in the indicators/stop lamps etc - without load resistors. At the moment if you try to do it, the MOSFET will drive the low current LEDs, but you get the bulb warning - so I am hoping to be able to modify a BECM power board to bypass the lamp warnings altogether. But it's quite a way down the list of things to look at... The 30 door latches sitting in bits on my bench waiting to be cleaned and rebuilt are the first priority at the moment as I've got a list of latches I need to try and get done for people!
Oh dear, not much chance of coming back from 1.8!
I think I'll go the multi-relay route then. I think one for each lamp, and one to disable my main/full beam trigger will do it. I think I have enough connectors left from the old car to make it a plug and play loom rather than cutting anything, bar a little splice for the trigger.
Yeah, it got a new MF31-1000 battery put in... still - the one that came out was a MF31-750 and lasted just over 4 years, which I think in a power hungry P38 which is left sitting idle as often as mine get left at home alone, is pretty good.
Was so nice to get out and drive again last night though... been 9 weeks since driving anything, and hearing the V8 again was just lovely :)
Just got to get the LPG all working happily again now... I remembered getting a whiff of gas under the bonnet before I went away so have bought leak detector spray, and a few new bits of hose and clips etc to hopefully get it narrowed down and then I get try getting the gas tune done!
Interested to hear how the extra relays/wiring goes!
4 years with long periods of sitting around isn't bad at all,
I may have cut out my centre section of the exhaust recently, which has increased the smiles per gallon no end. I've been driving it almost every day for the last month or two, as on LPG it isn't costing me that much more than my old 530D, and while I'm going everywhere far more sedately... it's far more enjoyable!
It's a shame there is something down underneath that makes a bit of an unnerving noise when it gets hot that detracts from the rumble at idle. It's either cats, flex plate, torque converter or worse bearing related, but I can't put my finger on it. Over 1k rpm its gone, it doesn't sound like something trying to make a break for freedom, and it hasn't changed in 3-4k miles since I noticed it. Pretty sure it must have been done it since before I bought it, I just didn't notice, as you can't hear it inside the car unless you really listen for it. I pulled the sump off when I first heard it and wiggled all the big ends and while not very scientific, they all seemed tight when given a good wiggle. I think I'm going to keep one of the old blocks just in case I need an core for exchange down the line!
I saw on another thread you've got the LPG running well now, that can only help! I need to replace a split hose on my parent's red one soon, then hope that it works. LPG has to account for a lot of P38s still being on the roads at least in the UK these days.
Hoped to sort this little fog mod today, but one of the 'cute' little rabbits decided at 2AM, it would start stamping over, and over, and over again... for no reason. It's done this a number of times recently, and as well as being annoying, pretty embarrassingly I'm sure it must have woken up the neighbours. So today was spent sound proofing one of the hutches in a rabbit-friendly (ie, not readily edible) fashion. If this doesn't work, I'll prepare a pot instead.
Cat rattle would be my bet- a few large self taps in the right place is an easy short-term fix. <br>
A few large self taps in the right place would solve your bunny stomping (or rather stomping bunny) problem too :-)
It sounds a bit rythmic which is odd :/ You'll hear it on the weekend. If it is something bottom end-y, it hasn't changed at all, so I'm not that worried about it at the moment.
Anyway. Stopped raining and the sun came out last night so off with the bumper!
This is the main side of the loom. One relay disables the main beam feed that triggers the relays that swap the power source to the fog lights. The other is one of the two aforementioned power swapping relays.
This be the other side minus the coil trigger, as I cut it to length on the car:
For now, the relay sockets are held in place by some handy M6 captive nuts. I'm not entirely happy with the placements, but for now they will do. These two areas seem to keep fairly dry even in heavy rain, and I don't plan to go wading through anything deep to be honest either!
This is getting a bit out of hand... I've ordered some hydraulic crimpers to crimp all of these feeds together and fit a universal fuse box, but typically they still haven't materialised in the post.
Works perfectly! No error messages with or without the fog lights on, main beam or flashing. The relay positioning could be better, and I may redo them if I lay my hands on some sealed / water proof relays and sockets, just for peace of mind.
Fusebox is definitely needed at this point, which brings me to a question for those with MF31-1000 batteries - how much space do you have to the left of the battery when fitted? Between the inside of the wing and the side of the battery? Currently I have loads of room there with the little battery that I have, but if/when that fails, I'll be sticking an MF31-1000 in and want to make sure I keep enough room.
