I have an 03 MCS with 35,000 miles, and the Battery Safety Terminal has self destructed twice in the last 3 months. Not accident related, and no airbag deployment either. I've searched quite a bit and can't find a similar thread here or elsewhere. Has anyone seen this sort of thing? The dealer has ordered the necessary replacement parts, and they're rooting around looking for the cause, but aren't sure what's causing it yet.

 

I guess this is not such a usual problem as there haven't been any replies. The dealership has had the car since Monday now. I'll try to follow up when I hear something from them.

 

Silly question: what happens when the safety terminal self destructs?......does the car die? smoke? Does the MC have that safety or just the MCs ?

 

All minis have the BST feature. I think it was a technology developed by BMW. It's meant to cut power to the engine in case of an accident and is only supposed to activate when the air bags go off. A small charge separates the main lead from the battery. (In my car, it melted a little bit of the nearby plastic, and left a little black mark under the panel.) A separate lead continues to feed power to other accessories like the lights, the radio, the windows, etcetera. With the main lead separated, the starter no longer works and the car cannot be started.

 

Unless there is some short or pinch in the wiring related to the BST (the 'charge' has two small wires going from it directly to the airbag controller) there must be some problem with the airbag controller itself, since it's solely responsible for firing the BST charge.

The airbag controller sits between the shifter and the e-brake, under the carpeting.

This is the first I have heard of this occuring.

 

yep this is a new one good luck and keep us posted. Also I thought this was S specific?????

 

Yes, it's specific only to the MCS. The MC does not have the BST.

The reason it exists on the S is because the battery resides inside the passenger compartment. A long cable runs from the battery in back to the starter (stopping at the jumpstart terminal on the way). There is no way to practically fuse this circuit, since the starter draws such a heavy initial surge that would cause nuisance blowing of the fuse if made too small or not blow at all if too big. In a bad collision that would cause the wire to become jammed into the sheetmetal of the car, a short circuit is created. Since there is no fuse, this long cable could heat up and start a fire, or the battery would rupture, both dangerous situations. The airbag system fires the BST when the airbags are triggered, disconnecting the battery and preventing possible above scenarios. The BST essentially has a 'bullet' charge that pops the cable out of the terminal, and the large plastic cover around it catches the cable and prevents it from moving back and reconnecting.

To replace the BST, you have to replace the cable as well, which runs under the car and up to the jumpstart terminal. The cable itself is a few hundred dollars.

A MC has the battery under the hood. The wiring to the starter is such that it would be very difficult to short it out, so it's not needed. Besides, all of the potential dangers lie outside the passenger compartment.

Other BMW models that have the batteries inside the car nowadays have the BST setup.

The second cable in a MCS that goes to the front for all the accessories is fused with a 200 or 250 amp fuse in the orange box by the battery. That's the protection for that cable.

 

I've got the car back and got some more information so I wanted to update everyone...

It seems that the first time the car went in, the actual positive terminal on the battery itself had melted as a result of there being something wrong with the battery. They replaced only the battery and re-attached the existing cable.

They've said what must have happened was that the problem with the battery caused damage to the battery safety terminal in the cable, and so it self-destructed at a later date. This time around they've replaced both the battery and the cable.

So it seems the BST only failed once, and it was a result of the bad battery the first time around.

Slightly off topic... I'm a little worried about this sort of thing happening just as I'm about to hit 36K. I've had several other warranty items taken care of since I got the car, most of them minor, but a few were a little more serious like having the steering column replaced and having a gas tank sensor fail. Got me thinking a little about the extended warranty option, or selling and buying an 06, but otherwise I'm really happy with the car. I haven't liked a car this much since the MGB I had in high school.

 

which had the battery in the engine bay

 

Anybody know where to buy the BST cable for the MCS? I think the part number is 61 12 1608 931

 

I couldn't find anything with that part number, but realoem.com shows part # 61 12 6942 507 for the positive battery cable, which appears to include everything from the battery to the jump-start terminal under the bonnet. Pelicanparts has it for $315, but I don't know if that's a good price or not.

 

Thanks, that helped. I found another place says they can get it for $248 plus shipping. I'll post if that works out.

 

Bmw makes a repair kit for all their cars with the bst, except the Mini. The repair kit for an E39 5 series works great for our Mini's. A whole lot cheaper to .

 

I'm bringing this thread back from the dead again...

I recently had my airbag warning light come on. I started snooping around and I found about 2 or 3 inches of standing water in my battery compartment on my '05 MCS. Do you guys think it the water probably ruined the BST and is the culprit for the airbag light? I haven't had anything apart around any airbags so I don't see what else could be causing it. Thanks!

 

I don't think it is the water causing the airbag light unless it was high enough to short the battery. Usually it is the connectors under the passenger or driver seat that goes bad and has to be replaced. To be sure, you need to connect a scanner to the obd port and check the code for the light.

 

I have had the same problem on my '05 Convertible S and just brought it to the dealer, Prestige Mini in Mahwah, NJ on Monday. They just called me back to let me know that to replace the BST cable and all the other cable related to the battery it will cost $6,300, parts and labor . Any help is appreciated, since I love the car, but I don't have the money and don't really want to spend that kind of money on a 6 year old car.

Thanks,

Kelevra

 

I would ask for a more specific breakdown of the estimate - what exactly are they talking about replacing?

It wouldn't surprise me if a new BST cable and installation by a dealer cost $200-300 dollars, but for $6300, it sounds like they're talking about replacing the main wiring harness for the car (essentially re-wiring the entire car, with all the labor that entails.)

 

Scott, I appreciate your fast response. The service advisor asked me to stop by tomorrow morning so that he, myself, and the supervising technician can meet and he can show and explain to me more clearly what needs to be done.

He did mention that for the BST cable to be installed the entire interior of the car has to be removed . Also, he said that some other safety cable have to be installed that run underneath the car.

I love the car, but to spend this kind of money is insane.

Please HEEEEEEEEEEEEEEEEELP ! ! !

Thanks,

Kelevra

 

Can a person remove the BST component of the wiring? I mean, I know that new cable can be run, but could the system be lopped off and rewired to a standard terminal clamp? Or could the entire length be replaced?

 

I am guessing here, but when I bought my mini used, the BST had fired and was just jammed and wedged back together so it would make contact. The car ran as long as the connection was good. So I am guessing you could just bypass it with a standard battery connector. I replaced the whole thing to get the light on the dash to turn off. As it turns out, that did not fix the light! something else is wrong. If the BST is already fired, it won't hurt anything to try replacing it with a standard battery connector.

 

Well first off, I think the idea is kinda funny. But I refuse to believe that anyone is spending $400 on battery cables unless they have to-- and I could see the car potentially throwing fits once it notices part of the air bag system has been removed. HOWEVER, my issue is that I have a broken terminal clamp on my positive lead and I AM NOT spending $400 to replace a $2 part. As I type I recall that I have seen battery upgrades where the BST hardware seemed to have been removed. So I wonder if you just do it or if there's a procedure. With an easy access kill switch at my disposal, I have no issues with ridding my car of the setup. I'm worried I'm gonna throw the ecu into crazy mode though.

 

Bringing this back, I just had same exact issue with my Coop, got an SRS scanner and got a code saying by Battery safety switch is the issue. So I looked at my battery and I spotted some water in the compartment and thinking that has something to do with it!

Anyone found a fix for this?

 

Is your Mini a hardtop or convertible?

 

I have a hardtop

 

I have an MCS -03 ; recently the airbag light came on and stayed on. The dealer claims that the problem is a defective or faulty Battery Safety Cable that will need to be replaced to solve the issue. Estimated cost is $1,400.00!!!!!!!!

I prodded a little, and the answer I got was probably due to moisture or an accumulation of water in the rear battery compartment.

Sometime ago, before I had the airbag light come on, I had noticed some accumulation of WATER IN THE BATTERY COMPARTMENT, Although I got rid of the water, it seems that some corrosion took place and damaged the battery safety cable.


My questions:

1. Does anyone else have or have had such a problem? The cost seems very unreasonable - any ideas?
2. Is there a way to bypass this and turn-off the light?
3. A larger question: Should MINI bear some responsibility for a product that leaks water into the battery compatment?

Ideas are welcome please - it's just way too expensive a proposition!