Fault codes - 01 Supply (Teminal 30) & 0B Battery positive terminal isolation 1

[WoGGo]

01 M3 - stock apart from Eventuri, sits in garage unlocked and put on charge every week, battery is only a few years old.

Some months ago now I had the airbag light pop up on the dash, but the car starts and drives as per normal so it didn't bother me until now.

I purchased an Autophix 7910 (Ancel BM700) scan tool in an attempt to diagnose the airbag light; here are a few codes:

MRS Multiple Restraint System - 0B Battery positive terminal isolation 1

LEW Steering-angle Sensor - 01 Supply (Teminal 30)

EWS - 83 toleration of changing code increased with key # 8

I don't own, nor know how to use a multimeter, so what can do/check first, before I replace the positive battery cable and steering angle sensor?

Also, is there any issue with leaving the car unlocked, unlike modern cars that won't go to "sleep" in left unlocked?

[bagger]

Clear all the codes - see what comes back. Usually a good first step.

[WoGGo]

Clear all the codes - see what comes back. Usually a good first step.

Already done; those are the codes that came back/remained.

[liam821]

LEW Steering-angle Sensor - 01 Supply (Teminal 30)

Was the car running when you pulled the codes? If the car hasn't been started yet, you can probably ignore this code. Start the car and move the wheel and the code will probably go away. Unless your ABS/DSC lights are on, this is fine.

MRS Multiple Restraint System - 0B Battery positive terminal isolation 1

This happened to my car once. It's the yellow plug on the pyro fuse starter cable positive battery cable. Check to make sure it didn't come loose or get wet. Mine was fine on the battery plug side but came loose where it plugs in under the carpet next to the 250amp power cable fuse.

This little yellow guy:

[WoGGo]

Was the car running when you pulled the codes? If the car hasn't been started yet, you can probably ignore this code. Start the car and move the wheel and the code will probably go away. Unless your ABS/DSC lights are on, this is fine.

No it wasn't, and I do not have an ABS/DSC light... I'll check again with the car running next time.

This happened to my car once. It's the yellow plug on the pyro fuse starter cable positive battery cable. Check to make sure it didn't come loose or get wet. Mine was fine on the battery plug side but came loose where it plugs in under the carpet next to the 250amp power cable fuse.

This little yellow guy:

I can check/wiggle this cable whilst the battery is still connected?

[liam821]

No it wasn't, and I do not have an ABS/DSC light... I'll check again with the car running next time.

I can check/wiggle this cable whilst the battery is still connected?

Okay, yeah, then you can ignore the steering angle warning than, the car will 100% tell you via the ABS/DSC light if there is something wrong.

Yes, you can wiggle the cable. It's not attached to any airbag, but it IS attached to the pyrofuse that blows apart the battery cable in the event of an accident so I wouldn't try putting positive power into the wires haha. But just make sure both ends of that small yellow cable are plugged in correctly and no corrosion. If you want to be extra safe, unplug the battery.

[sapote]

I can check/wiggle this cable whilst the battery is still connected?

I would disconnect the batt cable before wiggling or unplug/plug these kind of connectors, just to be safe. Also discharge your body by touching the metal chassis before touching this cable.

[liam821]

I would disconnect the batt cable before wiggling or unplug/plug these kind of connectors, just to be safe. Also discharge your body by touching the metal chassis before touching this cable.

That's probably the better advice! haha

[WoGGo]

I would disconnect the batt cable before wiggling or unplug/plug these kind of connectors, just to be safe. Also discharge your body by touching the metal chassis before touching this cable.

That's probably the better advice! haha

Battery disconnected

Does anything stand out to you?... I've wiggled all I can, and nothing seems to be disconnected or corroded.

Does the black tape on the bottom of the yellow connector look factory?

I disconnected the yellow connector (in the first two pictures) and nothing appears to be corroded; I suppose I'll have to completely remove the "battery plug" side now.

Not that you can see it well in the first picture, but I take it the cable tie isn't factory?

[WoGGo]

I would disconnect the batt cable before wiggling or unplug/plug these kind of connectors, just to be safe. Also discharge your body by touching the metal chassis before touching this cable.

Just so I understand correctly, can I remove the pyro fuse from the terminal, check it over, and re-insert it back into the terminal?

[Pnick]

Just so I understand correctly, can I remove the pyro fuse from the terminal, check it over, and re-insert it back into the terminal?

You have the battery cable disconnected already so, it should be safe to do so.
The right term for that system as BMW calls it is BST (Battery Safety Terminal). You can Google it and get more information about it.

[sapote]

Just so I understand correctly, can I remove the pyro fuse from the terminal, check it over, and re-insert it back into the terminal?

The fuse is not the yellow object. The fuse is an explosive device inside the cylinder section. The two wires are for creating a heating element to trigger the chemical explosive substance, just like the old day photography flash light. When it explodes, the pressure push the two electrodes away from each other to open the contacts.

[sapote]

MRS Multiple Restraint System - 0B Battery positive terminal isolation 1

The computer sees an open circuit at the Pyro fuse 2 pins.
I would do this: disconnect batt, gnd human body, pull the yellow connector off, use a DVM to measure the resistance at the 2 pins of the fuse. Normal condition it should be around 2 ohms, and if it is open (infinite value) then the trigger circuit is bad. If the fuse 2 pins is not opened circuit, maybe the wires from here to the computer is cut somewhere.

[WoGGo]

The computer sees an open circuit at the Pyro fuse 2 pins.
I would do this: disconnect batt, gnd human body, pull the yellow connector off, use a DVM to measure the resistance at the 2 pins of the fuse. Normal condition it should be around 2 ohms, and if it is open (infinite value) then the trigger circuit is bad. If the fuse 2 pins is not opened circuit, maybe the wires from here to the computer is cut somewhere.

I unfortunately do not know how to use a multimeter (DVM).

But after watching a few videos on how to measure resistance, I assume the connector side would still need to be plugged in (or not?), and you would put a probe on each fuse pin.. like so?

[sapote]

and you would put a probe on each fuse pin.. like so?

No, the Pyro fuse is in the other part attached to the red cable. Look inside that smaller sq hole there should be 2 small pins.
(What you're talking is the rectangular yellow thing which house the electronic circuit that discharges the current to explode the fuse.)