Starting concerns

[alexandre]

Absolutely!!! Starts better than it ever has.

Regarding fuses 14 and 67... both mention Immobilizer on the card. Both were missing when I bought the car. As I was going through the car I put both fuses in place.

How 14 bypasses the immobilizer by removing it, again I don't understand the logic other than with fuse in, no 12v to starter wire with key in P3. With fuse out, I get the 12v.

Looks like I'll be getting a new key sooner than anticipated so I'll revisit this shortly and post back up the results.

Maybe the battery is completely dead ? I don't know if you can start the car without that. Battery replacements are like $50 through bmwgm5.com.

[Dave_B]

Which battery do you refer? The one in the key, or the trunk?

I know the battery in the key is dead for sure which is why I'm getting another key. Once I have a new key, that works and starts and so on with the car, then I'll cut open my key and replace the battery to have 2 working keys.

[danewilson77]

I wonder if there's any info out there on the net, about this cheesey ass fix (kind of like hockey tape covering the SRS light)?

[wsmeyer]

I have a theory based on the text document I posted above that explains what the immobilizer system does.

We know that there are 3 fuses powering the EWS module. By observation we learned that 67 powers the door chime circuitry. What if 14 simply powers the code hopping circuitry?

If I'm right, the steps would be:

0 - car in immobilized state
1 - insert key
2 - code goes from key to EWS
3 - if code valid, new code generated and sent to key
4 - key writes new code to chip
5 - sends write confirmation to EWS
6 - EWS mobilizes car


Your key would intermittently fail step 4.

If you disable just steps 4 and 5, the code hopping part, you would still have to have one of the 7 valid keys for that EWS, but even if one of those had a dead battery it would still start the car.

[Dave_B]

I wonder if there's any info out there on the net, about this cheesey ass fix (kind of like hockey tape covering the SRS light)?

100% agree'd. Key is my next step.

[Dave_B]

I have a theory based on the text document I posted above that explains what the immobilizer system does.

We know that there are 3 fuses powering the EWS module. By observation we learned that 67 powers the door chime circuitry. What if 14 simply powers the code hopping circuitry?

If I'm right, the steps would be:

0 - car in immobilized state
1 - insert key
2 - code goes from key to EWS
3 - if code valid, new code generated and sent to key
4 - key writes new code to chip
5 - sends write confirmation to EWS
6 - EWS mobilizes car


Your key would intermittently fail step 4.

If you disable just steps 4 and 5, the code hopping part, you would still have to have one of the 7 valid keys for that EWS, but even if one of those had a dead battery it would still start the car.

Being an idiot with circuitry, your logic seems spot on. I am very curious what happens with a new key. I'd love for this thing to be 100% correct.

[alexandre]

Which battery do you refer? The one in the key, or the trunk?

I know the battery in the key is dead for sure which is why I'm getting another key. Once I have a new key, that works and starts and so on with the car, then I'll cut open my key and replace the battery to have 2 working keys.

Oh if you only have one key, it's a good call to get a 2nd one. But yeah, the guy at bmwgm5 replaces key batteries for like $50.

[Dave_B]

It looks pretty easy to do on the key battery.

Knife
Glue
2020 Panasonic Battery

Just want a 100% working key with EWS non bypassed before monkeying with current non-working key.

[telijah]

Oh if you only have one key, it's a good call to get a 2nd one. But yeah, the guy at bmwgm5 replaces key batteries for like $50.

OK, scond time I've seen this, and that is highway robbery. I got mine on eBay for like $5, soldered on myself and was done. Now, if he is charging $50 for you to send him your key and have him do it all, then I guess that's a fair price.

[Dave_B]

If I'm right, the steps would be:

0 - car in immobilized state
1 - insert key
2 - code goes from key to EWS
3 - if code valid, new code generated and sent to key
4 - key writes new code to chip
5 - sends write confirmation to EWS
6 - EWS mobilizes car


Your key would intermittently fail step 4.

Back to this. I think your on the right track here.

I spoke to my step dad who taught the BMW step program for UTI down in Orlando. After some discussions, we agree that this is a likely reason the car starts without the key in the ignition. HOWEVER, the key is not energized by itself. Battery in the key only serves the door lock and trunk functionality. The RFID chip that communicates with the EWS is done via what we know as the EWS Antenna in the key cylinder.

He seems to think that yes, pulling the fuse bypasses a few steps of the starting process, but also thinks I may have a bad antenna.

We are going to mess around with the GT1 he brought me this weekend and see if we can get it to communicate to the DIS/SSS program. If that works, then we can watch live if the EWS see's the key chip or not. Then we can really troubleshoot this issue.