BXProject

stu · Post by **stu** » 13 Jan 2008

Has anyone else noticed how this section has more posts about XMs than BXs in it?

Driving up to visit my mate James today. Stopped for petrol, and when I turned the car back on the brake failure warning lamps failed to go out. I was half-way there, and he's quite good at fixing cars, so I opted to press on - especially as XMs are prone to lighting up warning lamps when there's not actually anything wrong.

On this occasion though, they were accurate. My brake lamps don't work.

Here's what we did.

Cleaned and tested the rear lamp clusters (because I've had intermittent failures on one side before, and that always helped temporarily), then figured out which connection on the connector block is which and discovered zero volts being delivered to the brake lights on either side. Incidentally, the tail lights were only getting 10 volts so there's obviously electricity bleeding out along the length of the car...

Checked the fuse - OK. Checked that there was power at the fusebox - yes.

Took apart the brake pedal to test the switch. There are 12 volts at the switch, and according to the multimeter the switch works.

So what the hell is after the switch that's causing the problem?

I don't have a Haynes manual so we rang James' Dad, who's had an H-plate SED for years. He had a look at the wiring diagram, and it seems that the lamp failure module is between the switch and the lamps. Looks like that might be our culprit!

Unfortunately, he couldn't tell us where it is, physically, in the car because his Haynes manual was wet, having been in the boot of his XM, and the pages in that part of it were stuck together. So... where is it? Are they known to fail in this way? Can it be taken apart, cleaned, fixed? Or am I looking at a new one? Are they available?

David - this is why I called you today! We'd reached one of those headscratching moments and thought you might have some input. I was driving home when you rang back, using my manual brake lights (otherwise known as rear fogs). The car is now parked up and will not be used again until I fix this - one rear-end collision in a year is quite enough, thank you...

David · Post by **David** » 13 Jan 2008

My knowledge and experience of XM's is limited... very limited. Yours was the first one I've really done anything on TBH, and that wasn't a massive amount of work. Plus I realise now I was really rather hungover that day! But:

Given that the lamp failure module is capable of detecting one brake lamp out, and knows which one it is, I would guess that it's also the point at which the single switched feed from the pedal switch becomes two separate feeds for the lamp clusters. Because of that, and the fact that the sides/fogs will be wired the same, I would expect the failure unit to be somewhere towards the back of the car, as that would save on wiring. Maybe in the side of the boot or between the lamp clusters? I remember my SD1 had a lamp failure unit and that was in the extreme rear of the car.

Once you've found it, it's a simple case of finding which cables are related to the brakes and then measuring to see if you have +ve at the input from the pedal switch, and then if you have +ve from the output to the clusters. Chances are what you'll actually find is a rather corroded connector.

Lamp failure units aren't known for failing themselves (in general, I don't know about the XM one) so if it has failed, or has a nasty amount of corrosion in it I would guess someone breaking an XM would be able to sell / give you one that both works, and they don't need to keep as a spare.

docchevron132 · Post by **docchevron132** » 13 Jan 2008

It should be in the back end in the rear O/S wheelarch area, viewable after peeling back the plastic things in theboot.
Thats where it was on mine anyhow.
Had hours of fun with that fucking thing..
Kept telling me all sorts of eronious things, which took me ages to work out was in fact a shitty earth on the lamp cluster.
Anyway, assuming yours is a S1 vaguely similar speced car to the one I had then you'll find it there, small little black (or green, could be either) box with a multitude of wires going into it, all of which I would imagine will have shite connectors by now, since they were already shite when they left the factory!

stu · Post by **stu** » 14 Jan 2008

That's interesting. I was told on club-xm that it's behind the dash, near the parking brake. It would be MUCH easier if it's in the boot.

Of course, I can't get to it until next weekend now because I'm never at home in daylight

charlie · Post by **charlie** » 14 Jan 2008

My XM has an electrical fault.

count yerself lucky

my electrical fault has got an xm attached to it

hope you get it sorted

docchevron132 · Post by **docchevron132** » 19 Jan 2008

stu wrote:That's interesting. I was told on club-xm that it's behind the dash, near the parking brake. It would be MUCH easier if it's in the boot.

Of course, I can't get to it until next weekend now because I'm never at home in daylight

I would bow to their supierior knowledge.
Mine was in the boot, but to be fair, my car was a real oddity.
Absolutley nothing was where it shoud have been.

It started life in 1990 as a 2.0Sei auto, then got modded to Exclusive spec at some point before I got it, then I put a 2.1TD auto unit in it, and everything worked on it by the time I blew the engine up!

Anyhow, good luck!

stu · Post by **stu** » 21 Jan 2008

David was down to visit today, and (typically) sorted everything in double-quick time. I'll have a go at diy jobs but it is humbling to see a professional at work. Ho hum.

The chap on club-xm who said the lamp failure module was near the handbrake lever was right - but unfortunately mixed in on a thread which gave three possible locations (and some really random rubbish, but there we go).

The hardest part of gaining access was buying a torx screwdriver - not easy in Lewes on a Sunday, especially when the spotty children in Halfords don't know the difference between a torx screwdriver and a torque wrench

There are a few electronic black boxes behind the plastic panel above the pedals, one of which was dangling about without its cables plugged in properly. David pushed the cables in and voila - two working brake lamps.

Jobbed

I wish they were all that easy...

mickey taker · Post by **mickey taker** » 21 Jan 2008

he is a gent that David and a genuinely nice guy to boot

( not that I am suggesting you should boot him of course )

David · Post by **David** » 22 Jan 2008

stu wrote:it is humbling to see a professional at work

It often can be. Why didn't you tell me you'd seen one? I'd have quite liked to watch too...

Maybe I should have watched you while you were cooking....

t'was indeed a good weekend.... well, aside from the journey there that is. Over four bastard hours to do a 130 mile journey. Clearly ridiculously slow considering it took me 130 minutes to do the same 130 mile return journey just over 24h later. An interesting blend of motorway, dual, single and country lanes.... not forgetting the UK's twistiest bit of road (zig-zag hill)

.. and how lovely it was to have a "morning after" fry-up that was quality food from an independent butcher. I never get the chance to buy like that, but I really wish I did.

The oiks in Halfrauds were indeed a complete and utter joke. Every time I go there I think "it can't be that bad", and every time it is. We ended up getting what we needed in Focus DIY in the end!

One quick tech question, aimed mainly at you Doc as I'm fairly sure you will know the answer off the top of your head: What is the correct torque-converter stall speed for the XM 2.0i auto? Stu was making mention of odd changing and sluggishness at pull-away. The fluid is clean, doesn't smell burned, is topped-up perfectly to the hot-max level and the car seems to drive well, but the stall speed was surprisingly high at 2400rpm when I tested it. The only other thing I noticed was that some of the gearchanges weren't quite as smooth as I would have expected. Not violent in any manner at all, just not as silky smooth as might be expected.

smiffy · Post by **smiffy** » 22 Jan 2008

Sounds like it might be running dexron III toilet cleaner in the gearbox. try changing it for dexron II transmission fluid, which gives a much smoother change!

john s

stu · Post by **stu** » 22 Jan 2008

David wrote:It often can be. Why didn't you tell me you'd seen one? I'd have quite liked to watch too... Mr. Green Maybe I should have watched you while you were cooking....

You flatterer. I'm a good home cook but no pro - it was embarrassing to see you whip through the XM's wiring about 10 times quicker than James and I managed it last weekend with lots of headscratching and "well that *should* mean the problem isn't there."

docchevron132 · Post by **docchevron132** » 24 Jan 2008

The stall speed should be no higher than 1900RPM.
Could be any manner of things, including DIII, but DIII would also give "flaring" when changing from 3rd to 4th, and generally make the box slippy.
If it does have DIII in it, then get it the fuck out pronto if it isn't too late already.

It could of course just be low line pressure, easily sorted by adjusting the kickdown cable.

Changing the oil filter can work wonders too, since they NEVER get changed, EVER.

David · Post by **David** » 24 Jan 2008

docchevron1472 wrote:The stall speed should be no higher than 1900RPM.

I had a feeling that might be the case, as I've never heard of a stall-speed higher than about 2000 before now.

The only other symptom that Stu mentioned was an "indecisiveness" in the gearbox under certain conditions where it changed up and then down again, and then up again when going up a slight gradient. I dismissed that as I've had autoboxes do exactly the same before now. A small change in power removes the problem completely.

As for the fluid in the box... it's clear, almost crystal clear and surprisingly difficult to read the level on the dipstick. It also didn't smell of anything at all. I was expecting a red-ish fluid with the characteristic smell of ATF... any guesses?

It was almost a shame that we found it to be at the correct level. With a stall speed of 2400rpm I was hoping to find the level low.

docchevron132 · Post by **docchevron132** » 28 Jan 2008

Clear fluid, no smell..... AWOOGA AWOOGA IT'S DEXRON III...
Get it the fuck out! replace with DII, run for 500 miles, do the same again, and keep doing it till the fluid that comes out is as red as the fluid going in.
Oh, and change the filter too. Pronto. Otherwise the box will blow itself to pieces, if it isn't too late already. DIII will cook the brakeband in about 3 seconds.
It would also go some way to explaining the high stall speed.

The indecisiveness will almost undoubtedley be down to the kickdown cable requiring adjustment. Given the high stall speed aswell it's clear the line pressure is too low.

stu · Post by **stu** » 18 Feb 2008

docchevron1472 wrote:Clear fluid, no smell..... AWOOGA AWOOGA IT'S DEXRON III...
Get it the fuck out! replace with DII, run for 500 miles, do the same again, and keep doing it till the fluid that comes out is as red as the fluid going in.
Oh, and change the filter too. Pronto. Otherwise the box will blow itself to pieces, if it isn't too late already. DIII will cook the brakeband in about 3 seconds.
It would also go some way to explaining the high stall speed.

David, are these bits your friendly motor factor could get hold of? I may feel a trip westwards coming on, if that's ok with you?

David · Post by **David** » 23 Feb 2008

stu wrote:
docchevron1472 wrote:Clear fluid, no smell..... AWOOGA AWOOGA IT'S DEXRON III...
Get it the fuck out!
David, are these bits your friendly motor factor could get hold of? I may feel a trip westwards coming on, if that's ok with you?

Yes, and yes.

(I wish all questions were as easy to answer)

stu · Post by **stu** » 24 Feb 2008

David wrote:
stu wrote:
docchevron1472 wrote:Clear fluid, no smell..... AWOOGA AWOOGA IT'S DEXRON III...
Get it the fuck out!
David, are these bits your friendly motor factor could get hold of? I may feel a trip westwards coming on, if that's ok with you?
Yes, and yes.

(I wish all questions were as easy to answer)

Orsum. I'm hoping to get some well-deserved time off in March or April and visit my Grandma, so we'll make a plan when I know I can get time off (we're ridiculously short-staffed at the moment and my boss is leaving at the end of the month so FSM only knows when that'll be).

Can you find out how much it'll come to?

Oh, and if he can get a thermostat housing too that would be good.. the bleed screw thread seems to have stripped. It's not losing water, but it just turns and turns!

Surprise surprise. My XM has an electrical fault.