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Hi guys,
I'm new here so please forgive me if this thread is a bit messy.
I have an e34 518i, the problem started a couple of weeks ago... the central locking could not be activated by the passenger door key, it would just lock that door only. The drivers door would operate the central locking but all the locks would open again and they would lock with a second turn of the key. Last week fuse no. 32 under the back seat kept blowing and when it blows there is no central locking, no elec. windows, the wipers will only work on the quickest speed and the ignition is imobilised (no starter, no spark and no fuel pump)..
Today I went to the breakers yard and got a replacement actuator for passenger door and another relay module (black casette type box under the back seat ) because the fuse didn't blow when that box was removed.
I replaced them and the car started, locked and unlocked and started again, everything worked perfectly.. Then half an hour later I went to take it for a drive, it unlocked and started no prob then I went to drop the drivers window and it didn't work... so I turned off the ignition and tried to start again and nothing.. I'm back to the same problem.. fuse keeps blowing and now I dont know what to do.....
If anyone has any suggestions I would really appreciate it coz I love this car and my wife is whispering " scrap it, scrap it"
Happy new year,
Ian.:confused
 

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Similar symptoms but fuses all ok

Hi,

I'm experiencing very similar symptoms with my 1996 E34 518i except that all fuses are OK, both sets (those under back seat and those in engine bay). I've checked the wiring at the boot hinge, and as far as I can tell, there were a few wires with cracks(the wire itself was OK) so I wrapped them with insulation tape. I would have thought it unlikely that wires shorting was my problem if the fuses weren't blowing anyway. I've also replaced the linked fuse on the battery +ve lead. Additionally, it seems that when the ignition key is turned to posn 2, if the abs light comes on with the rest, then the problem occurs, otherwise it doesn't. This latter bit with the ABS might not always apply, I just noticed it didn't light last time the car started.

I've now got an aditional problem in that I can't seem to unlock the back doors, even manually. Lifting the bolt does not release the lock mechanism in the door and once you let go of the bolt, it slowly returns to the locked position.

On the off chance, I'll try replacing fuse 32 on the off chance it looks ok, but isn't, and let people know if that works. Is there a common earth that could be causing the problem?

Any other suggestions would be appreciated.
 

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The problems that are caused by the boot hinge wiring issue are not only short circuits between + and -. The wires can bare and touch each other causing circuits to be made when they are not meant to be. Also the conductors of the wires can get broken inside the insulation where you can't see them.
May not be your problem but it's worth giving them a proper check.

As for fuse 32 check the wiring to the drivers door lock switch and the drivers door lock actuator switch are ok, not shorting or anything. Maybe where the wiring runs into the door.
 

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Thanks for that BFUK. Any suggestions as to how I can check the integrity of the wire within the insulation if there is no visible break in the insulation? I've picked up a replacement actuator for the drivers door (though think I've been supplied wrong part - looks to be for E36 not E34 so am trying to get it swapped this am). In terms of the wiring going to the drivers door, is there an easy way to check this, particularly where it runs through the hinge, without having to remove the door?
Thanks again for your help
 

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Just to provide some further detail on the problem, I have disconnected the drivers door actuator and am seeing no improvement (will try the rest although need to work out how to remove boot toolkit so I can remove boot trim to access boot actuator) so doesn't look like that's the issue. Ive also noticed when it plays up happen, the interior light flickers. Cold weather also seems to make matters worse. i.e. nwhen below freezing, unlocking only unlocks the door the key has was a break in the wire, would this be likely to happen, or is it more likely to be something like a dry joint in one of the VCR type modules under the back seat?

Recently, the alarm has also been tripping sporadically. Is there anything with the Serpi Star alarms that indicates what tripped the alarm? At least that would narrow the circuits down.

If anyone wants to be really helpful, then they could supply a wiring diagram for my car (E34 1995 518i) as I've only got the Haynes manual which is neither use nor ornament for trying to resolve this.

Thanks.
 

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Hey Gildersol, thanks again for the prompt reply.

OK, got to ask what you do you do for a living? Just curious cos you seem to really know your sh1t here:)

2 things, firstly where are these switches (Haynes is about as much use as a chocolate fireguard here!!) and secondly, do they feedback to the control unit? I'm just wondering why they might cause the locks to bounce?
 

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Thanks Ronnie, although I don't think that's the issue here. The problem was that the anti-theft device was still engaged so I couldn't open the rear doors to gain access to the box of tricks under the back seat.

Part of my problem now is that the weather is somewhat warmer than it was and it seems to play up most in the cold (i.e. sub zero C) - much harder to find the problem when it's not manifesting:(

As things have developed, so has my knowledge, so I have a clearer idea of what the issue is, and it may be that there are 2 seperte issues.

Effectively, when locking the car, the locks bounce. Turning the key a second time locks the car. However, if the alarm is set, several hours later, it will likely trip for no apparent reason (though again, this started with the onset of winter).

if it's really cold, then the vehicle will not unlock with the alarm fob, and turning the key in any of the doors which activate the central locking only unlocks that single lock and does not activate the central locking nor disable the anti-theft device, hence the rest of the problems. When the interior light was flickering, a relay could also be heard clicking under the backseat, and trying to start the car, the starter made the kind of noise you'd expect if the starter needed replacing. Seems like rather than the anti-theft being either on or off, it was flickering between the 2 states.

Gildersol's suggestion regarding a switch (locking or light) sounds quite possible as a cause here, which is why I was asking where the lock switches are located. Are they part of the lock mechanism? Is it something that can be tripped manually to test?

Again, thanks for all the help:)
 

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If you look at the diagram on the link I posted, under central locking or interior lights, you will see the door lock switches and door jamb switches. If you look at the reference no.s next to them, you can then follow the section called component location, you can see diagrams of their location.

There's no guarantee, it's just a suggestion:thumbsup
 

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Again, thanks everyone for the help. The problem with the back doors is that if the temperature is cold then whichever way I try to unlock the car does not activate the central locking and therefore does not deactivate the anti-theft system. Without being able to open the back doors, I can't get at the rear lock mechanisms and have severely restricted access to the box of tricks under the rear seat.

The locking has "bounced" on and off for a couple of years, but recently, the alarm has tripped for no apparent reason, and now, if it's cold, I get an additional beep to indicate that something isn't closed.

What I have also noticed very recently is that the rear passenger side footwell is soaked (water getting in somewhere) and the insulation under the box (with the relay and general module) is also pretty sodden. Could this be primarily because the electrics are getting wet?

Thanks again everybody.
 

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Again, thanks everyone for the help. The problem with the back doors is that if the temperature is cold then whichever way I try to unlock the car does not activate the central locking and therefore does not deactivate the anti-theft system. Without being able to open the back doors, I can't get at the rear lock mechanisms and have severely restricted access to the box of tricks under the rear seat.

The locking has "bounced" on and off for a couple of years, but recently, the alarm has tripped for no apparent reason, and now, if it's cold, I get an additional beep to indicate that something isn't closed.

What I have also noticed very recently is that the rear passenger side footwell is soaked (water getting in somewhere) and the insulation under the box (with the relay and general module) is also pretty sodden. Could this be primarily because the electrics are getting wet?

Thanks again everybody.
Get checking that fusible link then, :thumbsup

And yes, if you have water ingress into the car it for sure can give you electrical problems, if it's damp under the rear seat base then it could have got into any of the control modules or fuses or fusible links and create problems.

Looks like you are going to have to clamber around a bit and remove the rear seat base with the rear doors closed.(It's easy, done a few myself) :hihi
 

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Thanks for that Ronnie. Luckily, this time I left the back seat out:) so access isn't so hard. I've removed the modules to see what happens in a bit once they are warmer and dryer. Looks like I need to work out where the water's coming from, but on the upside, I could end up solving all problems at once:)

I'll let you know how I get on and thanks again for the assistance.

(Oh, and changed the fusible link about a week ago - needed doing as it was split, but made no difference)
 

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Hi Again,

While I know how to use a meter, I'm certainly no electrician, so am looking for a little more assistance if anyone can help. As part of this, I changed the drivers door actuator, but before re-connecting, I checked voltage to the pins feeding it and am seeing about 1.5 at one pin, .7 at another, and 0v at any of the remining pins. I would have thought the motor was 12v so would have expected to see 12v at at least one of the pins?

The diagrams I can find, including those referred to Gildersol seem to cover pretty much every model apart from the 518i and to be honest, I can't read the diagrams well enough to work out what voltage I should be expecting to see at the connectors going into/out of the power distribution box under the rear seat. Since this is sitting in water, I'm assuming for the moment that this is likely where my problem lies.

Does anyone know what voltages I should be expecting to see at the connecters going into and out of that module and at the relays/fuses? I'm hoping I can verify that the power to that if I check the voltage at each of these pins and they are OK, then replacing it and the 2 cassette type modules and rechecking voltages will tell me whether I'm either losing power to that unit and whether something is wrong with one of the VCR looking modules. I need to remove it anyway to try to get it dried out underneath and see if I can see where the water is coming from.

Thanks again everyone:)
 

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I think the wires at the actuator are
red/green
white/black
white/green
white
blue
black

with one probe of your multimeter on a known good earth you should see
+12v all the time when you touch the other probe on the red/green wire (as long as fuse 32 is not blown)
+12v on the white/black wire when lock is in unlocked state
+12v on the white/green wire when lock is in locked state

The other 3 wires are more difficult to explain as the voltage changes polarity as the lock is locked/unlocked.

If you put one probe on the white wire and the other probe on either of the blue or black, you should see either +12v or -12v as you lock/unlock the actuator.
 

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Thanks Gildersol. I'm definately not getting anything like that to the actuator. Any ideas what the voltages are supposed to be to the power distribution unit under the rear seat? The whole area under that side of the back seat and the footwell are soaked. My hunch is that either the relay module or the general module are now bust as a result of the water, but just hoped to check the voltage was OK to it before looking at changing the modules.

PS recently made redundant, so don't have much cash, but if I've still any left once I get this resolved, I'll see if I can elp towards the forum target for the month. Least I can do after all the assistance.
 

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OK, sorry for yet another post here, but I think I might be finally getting somewhere. In the power distribution box, there are 2 modules that look somewhat like VCR casettes. One has 2 large connecters all of which are large pins. The other has 4 connector blocks, one end is a connector with 5 large pins. At the other end is a yellow connector block with what looks to be 26 small pins. Does anybody know what passes through that yellow conector? Something has been spliced in and with the water issue, I think it likely to be where my problem is.

Thanks again.

It looks like something (possibly the alarm) has been spliced into it (wires soldered or twisted and wraped in insulation tape). If that block ties into the electrical areas manifesting problems, then my guess is my problem is the splices compined with them being sat in water.
 
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