Hi all

Yesterday, I had a strange and new experience with the Disco.

I parked up and stopped the engine, left the family in the car, as I was only very briefly stopping in a shop. Was away from the car for 4-6 minutes max. The car had had a "proper" drive previously (of some 30+ miles), and was properly warm - with no previous ill effects.....

When I came back in started the car, she missed the first time. Took the key back round to start and did it again. She started. Moved her in D, and pulled away.

She seemed slow to actually start moving, although I didn't immediately notice this as anything really untoward. When I say this, I mean, that she just seemed slower to react to the throttle than normal.

Pulled onto a single carriageway, and then noticed that the green "S" and "M" lights were flashing on the dahsboard. I know that one is "Sport" mode, but didn't know what the other one was. I looked down and the "D" lights on the auto-box itself was also flashing - and I became more than a little concerned!

I couldn't safely pull over for about half-a-mile, but she made this ok. I pulled up, shut down the car, removed the car, locked and then re-opened the doors (to simulate a full shut down), and then restarted.

She was fine - no repeat of the behaviour at all, and nothing since. No flashing lights, and no further problems.

Whilst I don't want to go looking for trouble as it were, I am concerned as to what this might be indicating as a problem, and if this is something that does need addressing, I would like to - it's the family transport and I would rather not have it leave my wife/children abandoned somewhere!

If anyone knows what this problem indicates / could lead to, it would be very much appreciated!

Common problem mate, do a search there are loads of answers / comments on here. With mine I had to switch off and all was OK again, also something to do with loose connections below gear shift.

Some one will put ya right. But do a search first.

There are many reasons for your cars autobox to go into limp home mode - the only way to find out with your car is to hook it up to Testbook and read the codes.

Sometimes many electronics need a second or two to reset i.e. capacitors to drain to earth, often a quick on/off/restart does not give the electronics a chance to get themselves ready for a restart.

If you wish to put the car on testbook for peace of mind then go ahead but do not be surprised if 'no fault' is returned, this happens quite a lot not just on landies.

regards

Dave

Dave 2000 said:

Sometimes many electronics need a second or two to reset i.e. capacitors to drain to earth, often a quick on/off/restart does not give the electronics a chance to get themselves ready for a restart.

If you wish to put the car on testbook for peace of mind then go ahead but do not be surprised if 'no fault' is returned, this happens quite a lot not just on landies.

regards

Dave

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Thats fair comment - but the EAT ecu will have logged a fault,most likely a CAN message missing,low battery voltage on boot up will cause this,as will loom wires shorting on the AC comp,cyl head,or the top of the transfer boxor a WXYZ switch falling over or full of water.If the battery is old then fair enough,but if its young and healthy I'd still get it checked out,planned repairs are always cheaper/easier/more convenient plus driving in limp mode is not kind to the box.Any decent indy should read the faults for around £30.

I had the same fault, and phoned an indy. They said common fault, most likely gear selector switch, and probably about £200 to fix. He did also say, if it doesn't happen very often, just turn off car to reset, then restart. No other problems should occur. I did notice that mine did it, when i used the sport button.
Jon

eightinavee said:

Thats fair comment - but the EAT ecu will have logged a fault,most likely a CAN message missing,low battery voltage on boot up will cause this,as will loom wires shorting on the AC comp,cyl head,or the top of the transfer boxor a WXYZ switch falling over or full of water.If the battery is old then fair enough,but if its young and healthy I'd still get it checked out,planned repairs are always cheaper/easier/more convenient plus driving in limp mode is not kind to the box.Any decent indy should read the faults for around £30.

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Hi Dave and Eightinavee

Very much appreciate your input - thanks!

The battery is probably knocking on a bit. We've had her for a couple of years, and the battery is the same as was in there when we got her. Is this a possible cause?

She's never failed to start, or turn over or appeared in any way weak or lacking in capacity - always a very reliable start even on the coldest of mornings.... The only real bother we've ever really had was with the suspension compressor, but appreciate that this is a pretty common fault too!

It's also been suggested as being the XYZ switch on the auto-box... Likely do you think?

hue said:

I had the same fault, and phoned an indy. They said common fault, most likely gear selector switch, and probably about £200 to fix. He did also say, if it doesn't happen very often, just turn off car to reset, then restart. No other problems should occur. I did notice that mine did it, when i used the sport button.
Jon

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That's interesting - thanks Jon. Mine was also in Sport mode when it happened.... Is it something you just left and reset when you needed to?

As mentioned earlier, faults or rather 'odd happenings' can be caused by a battery that falls below a certain threshold during cranking.

If the battery is a bit long in the tooth then replacing it should be done sooner than later.

regards

Dave

Hi
Had the same problem for a while on and off. Looked at every thing and in the end simply replaced the XY switch on the side of the gearbox, awkward to get to but easy to sort out. Took about 1.5 hours to remove and replace, hardest bit was realigning the switch to the sensors but take your time and be logical. Cost from the main dealer was £126 ouch! Dreams like a dream now and no issues which is great.

climber said:

Hi
Had the same problem for a while on and off. Looked at every thing and in the end simply replaced the XY switch on the side of the gearbox, awkward to get to but easy to sort out. Took about 1.5 hours to remove and replace, hardest bit was realigning the switch to the sensors but take your time and be logical. Cost from the main dealer was £126 ouch! Dreams like a dream now and no issues which is great.

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Hi Climber

Thanks for this - this is the 2nd time someone has suggested the XYZ switch... I am presuming that if this part is at fault, that a nanocom or professional fault diag tool would report this?

£126 for the part is indeed a big ouch! I do hope it's not this.... Never had any problems with the gearbox (apart from the oil being a little thin and needing replacing a while back, which meant that it was very slow to change upto top gear until the engine was properly warm!)

This initial problem described at the top and the bloody rattle from the handbrake are the only real glitches. Oh, and the bloody window leaking air/water, and a and a yada yada.... It's a bit of heap really when I think about it! (only joking)!

Hi
I was told that nanocom/test book would pick up this but as I didn't have access to this and would have to pay the dealer I chose to go for the obvious. Everything else was checked including the battery and this was ok despite sitting around unused for 5 months. I searched for another supplier but in Guildford there was no one, the main dealer had 6 on the shelf and he confirmed that just about all the SM faults are caused by the switch. 2 10mm bolts and 13mm on the cable and then wriggle off. Poor clearance between gbox and exhaust and getting the electric connector off is the biggest source of swearing!!!
REplaced mine and enclosed in a tesco freezer bag to try and protect from the road crap and air con discharge pipe right above.
Have fun

Steven

rjsdavis said:

Hi Climber

Thanks for this - this is the 2nd time someone has suggested the XYZ switch... I am presuming that if this part is at fault, that a nanocom or professional fault diag tool would report this?

£126 for the part is indeed a big ouch! I do hope it's not this.... Never had any problems with the gearbox (apart from the oil being a little thin and needing replacing a while back, which meant that it was very slow to change upto top gear until the engine was properly warm!)

This initial problem described at the top and the bloody rattle from the handbrake are the only real glitches. Oh, and the bloody window leaking air/water, and a and a yada yada.... It's a bit of heap really when I think about it! (only joking)!

Click to expand...

It may be the XYZ switch but I wouldn't worry unless it happens repeatedly. Mine does it occasionally if I put it into gear slightly too fast after starting - I suspect it's just low voltage, given that my battery's nine years old. When you say "slow to change into top gear" you may mean "slow to lock up in top gear". If it's at about 52 mph it's just a design thing - gearbox has changed up, but won't lock up until it's warm.

climber said:

Hi
I was told that nanocom/test book would pick up this but as I didn't have access to this and would have to pay the dealer I chose to go for the obvious. Everything else was checked including the battery and this was ok despite sitting around unused for 5 months. I searched for another supplier but in Guildford there was no one, the main dealer had 6 on the shelf and he confirmed that just about all the SM faults are caused by the switch. 2 10mm bolts and 13mm on the cable and then wriggle off. Poor clearance between gbox and exhaust and getting the electric connector off is the biggest source of swearing!!!
REplaced mine and enclosed in a tesco freezer bag to try and protect from the road crap and air con discharge pipe right above.
Have fun

Steven

Click to expand...

Thanks Steven - this is really helpful and appreciated!

PASTMASTER said:

It may be the XYZ switch but I wouldn't worry unless it happens repeatedly. Mine does it occasionally if I put it into gear slightly too fast after starting - I suspect it's just low voltage, given that my battery's nine years old. When you say "slow to change into top gear" you may mean "slow to lock up in top gear". If it's at about 52 mph it's just a design thing - gearbox has changed up, but won't lock up until it's warm.

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Thanks Pastmaster - I'll be keeping a close eye on it. The difficulty is that it is the wife's barge primarily as a safe bus for the children - therefore, don't get to drive it as often as I would like. She's under strict instruction to keep a close eye on it though!

The gearbox was sorted ages ago... It just needed an oil change - the great news that I diagnosed it here on the forums, and saved myself a few quid ****ing around with the mechanic diagnosis time! Absolutely invaluable!!

Just for info, My TD5 Auto has been running fine for a while now but I left her in the works car park for 4 days while testing another car.
The battery was flat when I went to use her again and the S & M lights were flashing when I finally got her jump started. Turns out the battery was a bit old and was losing the charge which I didn't notice when using her daily. I drove home from work in Limp Home mode, switched her off for about 15mins (the battery now has some charge put back into it) and when started again, no flashing lights. changed the battery today. So my guess would be it could be connected to low voltage coming from a duff battery. Had it before when all the electrics got wet and I drained the battery trying to start her.

paul.ascroft@bmw.co.za said:

Just for info, My TD5 Auto has been running fine for a while now but I left her in the works car park for 4 days while testing another car.
The battery was flat when I went to use her again and the S & M lights were flashing when I finally got her jump started. Turns out the battery was a bit old and was losing the charge which I didn't notice when using her daily. I drove home from work in Limp Home mode, switched her off for about 15mins (the battery now has some charge put back into it) and when started again, no flashing lights. changed the battery today. So my guess would be it could be connected to low voltage coming from a duff battery. Had it before when all the electrics got wet and I drained the battery trying to start her.

Click to expand...

Yes, low voltage is a standard cause. As soon as your battery is putting out normal voltage you can reset the system by turning off the ignition and restarting. This is normal.

I changed oil and filter as was told mite b the prob then drove 5 miles no ms lights and changing gears perfect next morn back to the same thing ms lights on and no changing reverse seams to work ok

Best bet is to get it tested. if not start with getting the battery drop tested. After that it could be the xyz switch some people say that if the rear windscreen wiper works then it is not the xyz switch. My switch was faulty but the rear wipers still worked. I did the switch myself and it is quite easy.

Okey dokey...

So, this is my original thread from back in 2014, so you can see how long this has been going for! Long story short, it continued to occur, on the very odd occasion, from early 2014 until mid-2018. It was so infrequent, that we just lived with it.

However, during last Summer, it started to just get worse and worse - until eventually, the car became undriveable in that it was happening every single time the car was started. Long story short - everyone around here thought it was the XY switch, so a replacement gen unit was purchased, and fitted by my local indy specialist.

When we got the car back - all was well. It worked, drove normally, so we thought that it had indeed been the XY switch and that the replacement had cured the problem. Roll on about two weeks, and it started to happen all over again. Occasionally at first, and then, like before, got more and more often until, once again, it was happening every single time and once again the car was completely undriveable. We took her back to the specialist, and left her with him for a few weeks.

During the time that he had the car, the battery went completely flat. Before this had happened, the mechanic had been driving the car, and agreed that it was exactly as we described and was undriveable. However, oddly, once he'd restarted the car with a booster pack and started driving her again, the fault had gone. W T F?

He kept her for a week and bit and just drove her around, as he was as bemused and confused as we are. It didn't happen once. Not effing once. He hadn't done anything apart from allow the battery to go flat.

He called us, and asked her to take it back and simply drive her ourselves and see what happened. We've had her for about three weeks now, and like he experienced, not one single event. The reason for the post, is that neither of us are happy with not understanding why it was happening - and why it's not!

So, he obviously read the codes before the battery went flat. The codes recorded were:

P0758 - Valve 2
P0705 - PSM
P1612 - High Side Switch
P1843 - CAN timeout
P1842 - CAN Level

He told me that some of these (can't remember which) were to be expected as they were specifically caused by the car being in limp-mode, and that they were not the cause - just side-effect fault codes linked to the results of the actual problem. Fair enough.

He'd also pulled the gearbox apart to check all of the looms, as he'd experienced a couple of times before an identical problem - but this had happened previously, the gearbox had been shorting due to some wear on the earth, and it simply required a new local earth to be created to cure the problem - it wasn't that on this one, as all cables, pins, cable covers and so on were checked, and all were outputting correct voltages and were all earthing as they should.

I'd already borrowed and fitted a known working Bosch gearbox ECU under the passenger seat, this made no difference whatsoever, and ruled out the gearbox ECU.

The XY switch was new, but just to be sure to rule this out - he also fitted, and then re-fitted another known working XY switch, and again, no change to the car. This appears to rule out the XY switch.

He couldn't actually find any problems with the gearbox prior to the battery going flat. The most he could find, was that he felt that the voltage into the battery was a little high - 15.8v. His view was that you don't get any electronic problems on these Disco 2's at all with low/under voltage issues. However, if the system is running even a little over-voltage, it can cause electronic issues and problems with electronic systems. He further concluded that there might be a problem with the voltage regulator on the alternator, and that if it were to happen again, check the voltages on the battery terminals - if they were up in the high 15v's, this might turn out to be the culprit - but to see what if it was happening. He thought it would less likely to happen again in these shorter winter months due to the increased draw on the electrical system, and that if it's going to happen again, more likely to be in the Spring/Summer where the draw is obviously lower - this all makes sense to me... and that if it were to happen again, next job would be to replace the alternator with another genuine Denso unit - which he thought "might" cure it.

Our mechanic is a top, helpful bloke - and I've got an awful lot of time for him. He wouldn't take any money for what he had done, as his view was that he hadn't actually fixed it. What a totally decent guy!

So, we're still none the wiser as to what is happening here. I thought I'd throw it out there and see if there any thoughts from the guys on here that might be able to throw their two pennies worth into the mix? For me, the most perplexing thing is why the problem just "comes on slowly" - it's electronic problem. These are either working or their not. It's either off or on. I don't really understand why the issue/glitch was very occasional before, turning into everytime over a period of months? For me, this seemed like it might have been electric cable wear where the outer gets worn off over a period of time, wiggles about in use etc, and would explain that sort of "problem creep" behaviour - but it isn't that in this case. Therefore, I'm really confused.

Many thanks for any replies.