Crazy electrical gremlin - car sometimes totally dead, until shaken or door slammed

[ericole]

My electrical gremlin started about a year ago with the hazard lights blinking when starting the car. Not every time, but a lot of the time. They would just come on - even though button was not depressed on the center console. Another thing that was also happening was that when the car got turned on, we'd have to enter the radio code to make it work. Just as if there had been a disconnection of power - but there had not been. This was like the hazard lights - periodic and random. Often enough to be annoying, but since the car was old and putting in the code worked, we just dealt with it.

Working with my independent BMW guy we finally decided that the hazard lights were acting like the alarm was actually being tripped, but in silent mode - thus the flashing lights. I finally just completely removed the BMW alarm box from under the rear seat - fully disconnected and put it away. We never activated it anyway since the key fobs wouldn't control the locks anymore. We'd reset the thing, the locks would work a while, then it would stop again. So I just pulled the entire alarm module to remove it as a source of potential problem.

Sometime around then I replaced the ignition switch with a brand new part from Bav Auto (part 61 32 8 356 026 Ignition Switch 1995 525i). That went off fine and it has worked great ever since.

For a while the hazard gremlin went away and I thought we'd fixed it with the removal of the alarm module. The code thing on the radio stopped as well. But over the summer the hazard light thing started happening again, but very rarely. One day the BMW guy wrote me and said he figured out what it must be - the fusible link. So one time while I had it there getting an oil change he replaced it -said the old one was definitely in bad shape.

After the replacement, all was well - UNTIL (you knew it was coming since I'm writing in the forum) the car just started dying! crap! Well, more accurate, wouldn't come on - already dead. We'd drive somewhere - everything working perfectly. Go to get back in - 10 mins later, hour later - usually shorter times - and NOTHING. Not like a dead battery (which is also new in the last year), but as if NO battery. Turn the key and NOTHING happens - no lights, no blinking, no dings, no nothing! After waiting a few minutes, opening/closing a door, shaking the car, whatever we've (so far) always been able to get it to start.

Of all days, it happened today when my wife had our son out to the store to get him some medicine (woke up with bad cold!). She first tried a hard slam of the door -nothing. Then she shook the passenger side of the car - and the hazards lights came on (no keys in!). She did some more moving around after waiting 10 or so minutes, and it started. She was able to drive home like normal.

It sounds like the guy in this post has (at least) one of the exact same problems as me:
Roadfly Car Forum & Off Topic Forum Community (http://forum.roadfly.com/threads/128...r#post12882255)

BUT, the response doesn't help me (I don't think) since I've removed the alarm module.

If ANYONE can offer any solid advice, I'd sure love it. We were hoping to drive this car until the transmission went (have 226,000+ on it!). I'd hate to have to replace it b/c of this crazy electrical gremlin. And replace it we would since it's my wife's main car. Our old Saturn seems to have died, so I can no longer drive that to work. Having to drive my working truck. What a pain!

thanks!

[Tiger]

Most likely your battery is pretty much dead... charge it up with a battery charger and get the battery tested at any autoparts store for free.

Second thing is your alternator maybe shot also. What is the voltage reading with engine at 2500RPM? at idle?

[genphreak]

By dead you mean no lights on the dash at all?

Tiger is dead right, if it suddenly happened, it could be battery- they die like that and sometimes even measure 0v, when they die.

Given the history- we would suspect battery from the start (years ago), so would have to have counted it out to get ot this point. Testing the battery is required, and needs to be done by someone that knows how it should respond, not just how a car battery should generally respond. Your BMW is **very dependent** on a solid and stable operational voltage. BMW dealers replace them a long time (ie 2 years) before they fail.

Many on the forums try to eek 7 years out of them... when 2 is probably what the engineers put in the schedule. We ask for trouble- and burn out alternators and lots of gas doing so :)

But regardless, the fusible link is a good thing to have reliably replaced.

It could be the fusible link if definitely not the battery. Measure the standing charge and if <12.5V, you have a problem. Should have 12.7V minimum to start.

Suspect in order:
1. Battery (also check it is a large DIN88 battery, the smaller DIN66 will work but not for as long (it will fail early as well as run out of capacity quickly in harsh conditions)
2. Fusible Link (they are not easy to install properly- requires inspection and testing)
3. Alternator Regulator (starts to provide erratic/intermittent charging of the battery)
4. Alternator

Did you only remove the optional Alarm module?
Did you leave the Drive Away protection/immobilisation (DWA) module?

[ericole]

By dead you mean no lights on the dash at all?
Yes, nothing - no lights, no reaction, no nothing. As if no power exists in the car. It's like the show Revolution!



Tiger is dead right, if it suddenly happened, it could be battery- they die like that and sometimes even measure 0v, when they die.

Given the history- we would suspect battery from the start (years ago), so would have to have counted it out to get ot this point.


I dont understand the above - suspected battery, but now counted out? As I mentioned, the battery has been replaced (less than a year) and also checked - it's working fine, terminals tight, etc. Since the non-starting thing happens very randomly, and not very often, I'd find it hard to be related to a battery. Bad connection, yes, but source - that seems unlikely to me.



But regardless, the fusible link is a good thing to have reliably replaced.

It could be the fusible link if definitely not the battery. Measure the standing charge and if <12.5V, you have a problem. Should have 12.7V minimum to start.


Well this was just replaced and I can only expect that he did the job correctly. He tested and inspected after installed and all was working fine. Not sure how else to check it.



Suspect in order:
1. Battery (also check it is a large DIN88 battery, the smaller DIN66 will work but not for as long (it will fail early as well as run out of capacity quickly in harsh conditions)
2. Fusible Link (they are not easy to install properly- requires inspection and testing)
3. Alternator Regulator (starts to provide erratic/intermittent charging of the battery)
4. Alternator

I believe all of these parts have now been replaced with OEM parts. I'll have to verify. Not sure what you mean by DIN88/66 battery - I'm guessing that's a size thing?



Did you only remove the optional Alarm module?
Did you leave the Drive Away protection/immobilisation (DWA) module?

Maybe? I removed the black box that had BMW on it, disconnected it from the power and electrical cables. I'm not sure what the DWA module is, so I'm pretty sure I didn't touch that. If it is something I can remove, I'm all for it!

thanks

[ahlem]

I would check every ground point you can find. Clean them and reattach. I would also pull every relay, one at a time and put it back. If you are getting corrosion you may have some circuit disruption. Next time it happens, try wiggling starter wires to see if you have internal corrosion an inch or so from any terminals.

[ScottyWM]

Many, many, years ago I had a problem with my car at the time where it would randomly not start after a new battery was installed, be completely dead with no lights, radio, anything. Noticed that driving over bumps or railroad tracks would affect this (kind of like shaking your car). Finally turned out to be the battery. As I recall they told me it had something broken inside that would periodically go open circuit. So don't assume that it's not the battery just because it isn't old.

[whiskychaser]

You dont mention the year of car so this is a wild stab in the dark. I have a micro switch on top of the battery which is closed when you put the back seat down. It is clearly part of the security system as I get hazards on and the car will not start if I dont hold that switch closed when connecting the battery. This doesnt happen every time and I am not in the habit of removing the back seat. It just seems to fit with banging or shaking the car as that may make the connection.

[genphreak]

I don't understand the above - suspected battery, but now counted out? As I mentioned, the battery has been replaced (less than a year) and also checked - it's working fine, terminals tight, etc. Since the non-starting thing happens very randomly, and not very often, I'd find it hard to be related to a battery. Bad connection, yes, but source - that seems unlikely to me. Well this was just replaced and I can only expect that he did the job correctly. He tested and inspected after installed and all was working fine. Not sure how else to check it. I believe all of these parts have now been replaced with OEM parts. I'll have to verify. Not sure what you mean by DIN88/66 battery - I'm guessing that's a size thing?

By counting the battery out I meant you must have done that by now as you got a new one. DIN88 is larger yes, which did you get? You should know before you buy as most car people will give you the wrong thing for your BMW if left up to them (most of the time) as they usually don't know, can't find out, guess or just don't care. Tip: Try not to place unfounded confidence in anyone other than BMW (even if they seem really smart) in fixing your car- else you pay later as doing so causes issues to occur and re-occur. For example, this is how a lot of cars get DIN66 batteries (ie, it fits, it works now = it must be ok).

Removing the alarm module is probably fine (people do this often on the forums). It is an add on item after all. Removing the DWA unit is not something to just do as it will upset other things/have consequences, etc.

You have a problem which you need to find the root cause of, not go attacking symptoms. It is bad to try to hack a BMW back into operational condition without some care and attention; even an e34. Certainly not like some people try/do with simpler cars and general knowledge.

BTW I forgot to add, right at the top of the list: You have probably done this, but just to be sure: verify the battery terminals are not corroded in any way. Also, if they ever were loose and anyone ran the engine, you may have a blown diode pack in the alternator (and charging will be intermittent/poor).

So again, you need to measure the battery voltage; you should do so standing 35s after running and being locked. Then again at 120s, 15 minutes and 45 mins and after being locked overnight. Then yo'll have a better idea of what is happening from the battery's perspective.

If still unsure, check what your guy did to the fusible link, it may be a bad repair and simply be loose/inapprpriately connected. This is important to check as it must be very carefully insulated- if touching a metal or painted/insulated surface other than rubber/PVC it could rub and short the battery out (or just slowly run it down)- and may could cause a fatal fire/be dangerous.

[ericole]

I did mention the year in my original post - 1995. VERY end of the run for this model car, second half of the year.

[ericole]

By counting the battery out I meant you must have done that by now as you got a new one. DIN88 is larger yes, which did you get? You should know before you buy as most car people will give you the wrong thing for your BMW if left up to them (most of the time) as they usually don't know, can't find out, guess or just don't care. Tip: Try not to place unfounded confidence in anyone other than BMW (even if they seem really smart) in fixing your car- else you pay later as doing so causes issues to occur and re-occur. For example, this is how a lot of cars get DIN66 batteries (ie, it fits, it works now = it must be ok).

Removing the alarm module is probably fine (people do this often on the forums). It is an add on item after all. Removing the DWA unit is not something to just do as it will upset other things/have consequences, etc.

You have a problem which you need to find the root cause of, not go attacking symptoms. It is bad to try to hack a BMW back into operational condition without some care and attention; even an e34. Certainly not like some people try/do with simpler cars and general knowledge.

BTW I forgot to add, right at the top of the list: You have probably done this, but just to be sure: verify the battery terminals are not corroded in any way. Also, if they ever were loose and anyone ran the engine, you may have a blown diode pack in the alternator (and charging will be intermittent/poor).

So again, you need to measure the battery voltage; you should do so standing 35s after running and being locked. Then again at 120s, 15 minutes and 45 mins and after being locked overnight. Then yo'll have a better idea of what is happening from the battery's perspective.

If still unsure, check what your guy did to the fusible link, it may be a bad repair and simply be loose/inapprpriately connected. This is important to check as it must be very carefully insulated- if touching a metal or painted/insulated surface other than rubber/PVC it could rub and short the battery out (or just slowly run it down)- and may could cause a fatal fire/be dangerous.

I have checked the terminals - they are happy and clean. I've actually never had an issues with corrosion on the terminals in this car.

Is this battery size something indicated on the battery itself? I'm pretty sure I got it at autozone - they only had one size that fit the car. I assumed it was the right one - maybe it wasn't, in terms of the numbers you are mentioning. But the mechanic has never said it was wrong.

thanks

[Tiger]

Do the voltage measurements.

[genphreak]

You might need to look at the battery to verify the type/model. DIN is a world standard, if the manufacturer doesn't mention it on the battery, it may not be a good one. I think some call the DIN88 a something else 85, but I've never seena DIN66 called anything other than a DIN66.

And make sure you verify the fusible link is not going open circuit in the heat/cold/under load whilst you're at it. Even if you have a DIN66 in there, you can check if it is good or not by measuring the voltages as I described prior.

Oh, and beware what the mechanic says, we're troubleshooting here. They make money from it, and sometimes have a slight knowledge deficit/disinterest when it comes to electrics.

[Mordan]

Hello

EVERYONE who owns a DIY car MUST have one of those

LCD Cigarette Lighter Voltage Meter Monitor Tester for Auto Car Battery 12V 24V | eBay (http://www.ebay.com/itm/LCD-Cigarette-Lighter-Voltage-Meter-Monitor-Tester-For-Auto-Car-Battery-12V-24V-/251035918894?pt=LH_DefaultDomain_0&hash=item3a72e8222e)

Look for the cheapest on ebay.

Those voltage reader come in handy to regularly check the battery and the alternator.

It is BLOODY usefull. I have 2 of those.

You can check during running if your atlernator is doing its job. You can see the voltage dropping when using electrical components and find a failure or ground on those components.

VERY VALUABLE. Buy one before making lenghty posts. :)

Cheers

Mordan

[genphreak]

... Buy one before making lenghty posts. :)

Or one can just unlock the OBC and get it to tell you real time voltage when driving or in position 2.

But such pointers are useless my friend.. no one wants to touch their car or do analysis :-(

Accessing the car's built in diagnostics via the OBC:

See the five and seven series procedure (http://www.meeknet.co.uk/e32/e32_obc_unlock.htm), or others such as e36, etc.

UNLOCK PROCEDURE:
1) Key to ignition Position 2 (no need to start engine).
2) Fasten the seat belt to get rid of the "Fasten Seat Belt" message (if built after 1996)
3) Press the right button on the instrument panel, and hold it until "TEST-NR. 01" comes up (5 - 10 seconds).
4) Press the left button on the instrument panel, and the vehicle id comes up (last 7 digits of VIN).
5) Add up the last 5 digits to get the "unlock code", e.g. the unlock code for "AB12345" would be 15 (1+2+3+4+5).
6) Repeatedly press the right button until "TEST-NR. 19" appears.
7) Press left button -> "LOCK : ON"
8) Repeatedly press left button until "LOCK : xx" appears, where "xx" is your unlock code.
9. Press the right button. All modes are unlocked now.

NAVIGATING BETWEEN TESTS AND PERFORMING THEM:

- Follow steps 1) to 3) of the "UNLOCK PROCEDURE" to enter test mode.
- Use the right button to step from test to test.
- Press the left button to enter a test and cycle between modes within a test.
- Press and hold the right button to exit test mode (turning the key to 0 works as well).

Here is what I know about the various test modes:

2) 0.0 V BR Instrument test: Cute light show in the instrument panel. Ever wanted to see the speedo show 190 without having to leave the garage?

3) 0.0 L/H Varying Instantaneous fuel consumption in l/hr Measurement

4) Current fuel consumption in litres per 100 kilometers and in litres per hour.

5) Average fuel consumption in litres per 100 kilometers and range.

6) Current fuel levels in left tank, right tank, and total.

7) Engine temperature (not sure where measured), engine RPM, and outside temperature.

8) Current speed in kilometers per hour.

9) Battery voltage.
10) 0.97 EICH Setting
Speedo meter correction *1 1000/100/10/1 button to change, S/R to save
This doesn't work on my car

11)
LA-J
LA-CAN
LA-F
LA-E
LA-I
LA-CH
LA-UK
LA-D
LA-US
LA-FCH Setting Country Setting for language, miles/km, C/F and "l/100Km"/"Km/l" 1000/100 button to change, S/R to save

12) Not sure what these are. Could be average speed used to calculate arrival time for distance to destination set in OBC?

13) Sound test. Goes through the various gong sounds.

14) 06.05.1987 89 735I *4
04.04.1990 92 740IA*4
Software Date of OBC NONE

15) 92 740IA*4 89 750ILA*4
DIAG Values Values
01 01 C1
02 52 52
03 C3 C3
04 04 A4
05 05 C5
06 06 C6
07 07 E7
08 00 20
09 00 02
Fixed Setting Diagnostic OBC values 1000/100 to up/down DIAG number, no manipulation, no save

16) Oil temperature. Sometimes gives a bogus -48 degrees C when the engine is not running. Corrects itself when the engine is on.

92 740IA*4 89 750ILA*4 89 735I*4
PORT Values Values Values
01 80/83/87 A0 C1
02 40 05 52
03 1E/5E 00 C3
04 16 1F 0C
05 02/06 46 C5
06 40 D0 C6
07 80 A8 A7
08 04/40/44 7F 70
09 0F 00 00
Varying OBC input port values, depending on engine running or not, etc. 1000/100 to up/down PORT, no save *3

17) 92 740IA*4 89 750ILA*4 89 735I*4
PROM Values Values Values
00 D1 9F 64
01 00 00 00
02 00 00 00
03 00 00 00
04 64 64 CA
05 78 64 6E
06 50 42 4C
07 28 24 2D
08 0E 0F 10
09 0C 0E 0F
0A 89 6E C8
0B C7 DE DD
0C DE F1 EE
0D E9 F6 FC
0E 00 01 05
0F 53 61 14
10 C6 C6 CB
11 36 6A 58
12 00 00 00
13 00 00 00
Fixed Setting Vehicle Specific Data, changing between car models NONE

18) HUPEDTION Setting Horn/Claxon, either single tone or double tone C/F to select, S/R to save

19) Locking & unlocking of the test modes.

20) FREI Setting UNLOCK/LOCK OBC functions,
Add current day and month (as known to OBC) and enter this value 10/1 to set unlock value and S/R to unlock, C/F to lock

NOTE: For instance, if the date was 12th of November, add 12 (the day) to 11 (the month) giving a value of 23; enter this into the OBC using the '1' and '10' keys and then press 'S/R' to unlock, if you need to lock the OBC then press 'C/R' instead.

20 1000 CORR Setting Correction Factor for OBC Fuel Consumption *2 1000/100/10/1 to change, S/R to save

NOTE: On my 730i V8 this is set to 1000 which is the default setting

21) PPPP Action Reset all defect codes, date and time S/R to activate, be carefull!
Selecting this function performs the reset- whatever it is! I don't know....
Note: Apparently the "PROM" values won't be reset.

[ericole]

I've never considered my car a DIY vehicle. So you are saying that without this voltage reader in my cigarette lighter I should not post questions to this forum?

[ericole]

Just an update - going to check the DWA module sometime this week. I'm in the process of building a house, so been busy with that and just got back from a trip for work, so haven't had a chance to do anything yet. Will also check the battery size. I did note tonight that when I turned the bright lights on the radio (playing a CD) cut out for about a full 1-2 seconds! crazy!

[genphreak]

Nothing to check in the DWA module, it has a fuse but it is not blown. Never seen one go wrong.

You need to verify the voltages and you could also check for water under the carpet too- esp the rear/back seat area.

Keep us posted on how you go. Remember that a car that drives once a week wears a battery 10x faster than one that drives once a day...

[ericole]

Thanks, I'm going to try to get under the carpet a little. Two weeks ago though I had the back seat out checking the battery, connections, etc. Even vacuumed all of that space out just to make sure nothing was in the way - all very clean and no signs of water ever having been in the space.

Car is driven daily, so the battery should be fine from that perspective.

Going to check the DWA to see if it is putting out error codes that might be related to the car not starting - as if it had been tripped or something. That will be next week.

[genphreak]

Eric, if your problem is no power at all, DWA is unrelated. It can't shut down power to the dash- only the OBC (and prevent starting (It employs the help of the EWS module to do that, IIRC). I found today, whilst disconnecting my battery that the auxillary positive cable (the thin one) had corrosion around its connection to the main terminal.It doesn't clamp with the force from the 13mm nut, so I took the bolt out, cleaned it up and greased it with Vaseline. It might be worth checking this on yours too- oxidised terminals can cause problems.

[Bill R.]

Its your fusible link, If you look at the schematic for the 1995 it shows 2 fusible links used, you have a hairline crack in one of them.

[Bill R.]

There is also a couple of other places i would check that come to mind..... There is a ground disconnect point behind a plastic cover in front of the battery on the carpeted section that the rear seat sits on. Take that cover off and check the ground connection there. I think your e34 also has a connecting point under the dead pedal where they originally had a battery disconnect switch when the car was being transported from the factory, the switches are removed at the dealer but the connecting point is still there and if it worked loose or got corrosion on it it could have an effect also.

[shogun]

here are pics of that ground wire on the rear seat
OJs Autobahn - 21_groundwire_exposed (http://www.ow.no/index.php?option=com_gallery2&Itemid=18&g2_itemId=140)
under this cover
http://www.ow.no/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=136&g2_serialNumber=1&g2_GALLERYSID=388f6bbd70781694253e48eee6dae665
OJs Autobahn - 19_groundwire_cover (http://www.ow.no/index.php?option=com_gallery2&Itemid=18&g2_itemId=132)

[ericole]

here are pics of that ground wire on the rear seat
OJs Autobahn - 21_groundwire_exposed (http://www.ow.no/index.php?option=com_gallery2&Itemid=18&g2_itemId=140)
under this cover
http://www.ow.no/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=136&g2_serialNumber=1&g2_GALLERYSID=388f6bbd70781694253e48eee6dae665
OJs Autobahn - 19_groundwire_cover (http://www.ow.no/index.php?option=com_gallery2&Itemid=18&g2_itemId=132)

I've always wondered why that plastic piece was there, but never had enough interest to check. WHY is it there? thanks, I'll check it this week/end while off for Thanksgiving. Also check the voltage stuff as mentioned.

[Mordan]

I've never considered my car a DIY vehicle. So you are saying that without this voltage reader in my cigarette lighter I should not post questions to this forum?

Sorry my friend but if it is not a DIY vehicle what are you doing here? Just drop your car at the dealer/mechanics and be done with it.

@genphreak. My euro cars don't have OBCs giving me all that stuff.

[ericole]

Can you show me where to see the schematic you mention? There was only one fusible link that we were able to find in my 1995 E34. thanks

[ericole]

I wanted to update b/c I haven't written anything in a while and I hate finding these forums and never seeing if the problem is resolved or not, so I don't want to leave this thread undone.

This hasn't happened in a while, so like happens with things like this I've sort of ignored it (especially since our new house has gotten into the final stretch and there have been things we've needed to do with that). 3 nights ago we were all going somewhere and my wife turned they key - dash lights, then fully dead. A full blow gremlin attack. She waited, tried again, same thing. Did that a few times until the key turn got no response - as if no battery existed in the car. We shook the car, slammed driver's side door, etc. Got lights a couple of times but that was it. Finally got my son out of his car seat in the back and noticed that when I opened the rear passenger door the interior lights came back on - they were off before that. Slammed his door shut and she was able to get the dash lights again, but no start. Started troubleshooting and found out that with either back door opening or closing the interior lights would come back on and we'd get the dash lights part - but no starting.

I called my mechanic since I was in the middle of a gremlin battle to get his thoughts. He suggested I take the back seat out, which I had already done to begin looking around. Battery terminals all still good, clean, etc. He recalled an old 7 series he had worked on that had the same strange behavior. He took off the negative wire, moved it around and reattached it in a different orientation on the terminal. That car never had the problem again. I forget why he said he tried that, but before I did that I tried to start the car. Voila - with the back seat out, and me having done nothing else, the car started right up!!! I did go ahead and move the negative wire like he suggested. I drove a couple of days with the seat out and haven't had any problem.

I did note that when I start the car that I hear some kind of relay or whatever click in the back seat area. Lots of other things seem to be controlled from there as well (I noticed the windshield wipers for one).

Anyway, it does seem that it is definitely localized in the back seat area. I checked to see if any kind of wire or wiring harness was in a place that the seat itself should be interfering with it. As best I can tell, everything is where it should be from the factory design. There is really no way to see this directly, but I can't imagine that the seat touches the battery. I assume it's all designed so that the battery comparment is deep enough to keep that from happening. My seat isn't damaged in any way, so it's not flexing down beyond where it should - at least I wouldn't see how it could.

So that's my last status - any thoughts?
thanks

[shogun]

on cars with anti theft/ drive away protection the car will not start when the seat is out and the drive away protection is on. Those cars have a microswitch on the cover of the battery and when the seat is lifted, the microswitch acts = no power. You can check all the details of wirings and parts which are under rear seat in the ETM = electronic troubleshooting manual, there are even pictures of those items at the end of the ETM under parts location views, select the correct one for your built year here
E34 (1988 to 1995 5 Series) Wiring Diagrams (http://shark.armchair.mb.ca/~dave/BMW/e34/)
E34 (1988 to 1995 5 Series) Wiring Diagrams
1988 e34_88.pdf (10,476,973 bytes) e34_88.zip (8,451,206 bytes)
1989 e34_89.pdf (10,863,822 bytes) e34_89.zip (8,588,005 bytes)
1990 e34_90.pdf (14,676,816 bytes) e34_90.zip (11,295,570 bytes)
1991 e34_91.pdf (18,332,496 bytes) e34_91.zip (13,399,412 bytes)
1992 e34_92.pdf (15,153,055 bytes) e34_92.zip (11,963,569 bytes)
1993 e34_93.pdf (15,214,090 bytes) e34_93.zip (11,994,722 bytes)
1994 e34_94.pdf (15,860,270 bytes) e34_94.zip (12,448,814 bytes)
1995 e34_95.pdf (15,392,094 bytes) e34_95.zip (11,897,304 bytes)

[Tiger]

If you lost complete power as in no battery at all, it is definitely the fusible links... there are a couple of them back there and some hidden.

The most basic is clean the battery clamps and battery terminal with the battery terminal wire brush thing.

I might even change the ground cable because it is so easy and cheap. Wires does go bad when corroded inside the wire insulation... more common in engine compartment but not really inside the car... still very cheap job.

[Dave M]

Thanks for posting an update to your story and ignoring the odd heckle from members that feel obliged to flex their inernets muscles. Seaking help is necessary to becoming a DIY'er.

Dave

[ericole]

I'm not really sure what to take from this other than wiring diagrams - hopefully identifying another fusible link. There is no microswitch on my battery. The car starts and runs fine with the seat out.

[genphreak]

Please forgive me for I may have missed some things when reading your thread again...

Have you:

1. isolated both fusible links? One runs the engine room, (fuel pump, ecu, etc.) and one runs the body electronics. The starter doesn't have a fusible link- the big red wire goes direct via the positive jump point on the firewall.
2. verified the battery terminals are properly cleaned and greased?
3. verified the ground wire to chassis ground terminal under the back seat is free of corrosion and connecting properly? (10mm bolt behind the plastic cover on the rear seat base (battery side), just below (not under) the seat cushion?
4. what have you done to verify the fusible links are **not faulty**?

The DWA/anti-theft microswitch on the battery is very obvious (and has a wire stopping you remove the cover from the general area) if you have not seen it and you'll only have one if your car has one of those items.

[Tiger]

I have that microswitch... it doesn't do a darn thing... I can start the car with the seat off. I do have that factory alarm.

[genphreak]

"I've never found it to do anything... "

Hey Tiger;

I've never found it to do anything either, but have not tested it. I believe for it to make a difference the following conditions have to be met:

1. Trigger DWA or Anti theft device and/or factory alarm
2. Remove the rear seat

Power will be shut off to the entire engine ignition and dash (or something like that)

[Tiger]

That is not true either... because at one point, the alarm triggered and won't shut off... so I yanked out the seat, unplug one wiring harness on the alarm unit and then I was able to start the car.

Although I did not test to see if I could crank the engine... I doubt it makes any difference bwcause if the alarm had the capability... it would simply done so while the alarm is going off. BMW alarm simply kill the ignition system. You can crank but it won't start... it is a kind of stupid alarm... because antennae reception is horrid and schizo... and the fact you can crank the engine would allow intruder to kill your starter by continious cranking beyond safety time limit.

[ericole]

please forgive me for i may have missed some things when reading your thread again...

Have you:

1. Isolated both fusible links? One runs the engine room, (fuel pump, ecu, etc.) and one runs the body electronics. The starter doesn't have a fusible link- the big red wire goes direct via the positive jump point on the firewall.

E: No, have only found one fusible link - not far from the battery. Looked at schematics someone else provided and couldn't find any info on the fusible link (or links), so can't find another one.

2. Verified the battery terminals are properly cleaned and greased?
E: Yes, multiple times.

3. Verified the ground wire to chassis ground terminal under the back seat is free of corrosion and connecting properly? (10mm bolt behind the plastic cover on the rear seat base (battery side), just below (not under) the seat cushion?
E: I've taken that cover off and totally removed the single, long bolt inside the black, recessed hole. It came out smoothly with no signs of corrosion. I put it back tightly.

4. What have you done to verify the fusible links are **not faulty**?
E: What does one do to verify a brand new fusible link is not faulty?

The dwa/anti-theft microswitch on the battery is very obvious (and has a wire stopping you remove the cover from the general area) if you have not seen it and you'll only have one if your car has one of those items.
:kl

[genphreak]

No I am sure it is an input to the factory alarm and DWA. It probably triggers the alarm if its armed and the seat is removed. If the alarm or DWA is triggered, there will be no fuel, cranking and possibly no spark.