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

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 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