[3azy92]

So I’ve been having an issue with my 328i where it will only crank and the engine will not fire. I get codes 2E7C on the DME and A0B4 on the CAS. The 2E7C is a BSD error and when I try to diagnose it on ISTA, it says that it’s a permanent fault and would like to know if I need to change the DME out. And help is much appreciated. Just trying to get my car on the road again :/

[e91Owner]

Originally Posted by 3azy92

So I’ve been having an issue with my 328i where it will only crank and the engine will not fire. I get codes 2E7C on the DME and A0B4 on the CAS. The 2E7C is a BSD error and when I try to diagnose it on ISTA, it says that it’s a permanent fault and would like to know if I need to change the DME out. And help is much appreciated. Just trying to get my car on the road again :/

Have you tried jumping the car or letting it charge overnight, then attempting a start? My guess is that your battery is low and you are getting an IBS fault off the BSD causing the 2EC7 code. The A0B4 code just means it's not starting when you are trying. That's just a guess given you have both simultaneously.

[3azy92]

Originally Posted by e91Owner

Have you tried jumping the car or letting it charge overnight, then attempting a start? My guess is that your battery is low and you are getting an IBS fault off the BSD causing the 2EC7 code. The A0B4 code just means it's not starting when you are trying. That's just a guess given you have both simultaneously.

I have a battery charger/maintainer and have fully charged the battery, the starter kicks right up every time

[e91Owner]

On ISTA, were all of the units on the BSD powered? Did you check voltage between the block and the + terminal in the engine bay?

[3azy92]

Originally Posted by e91Owner

On ISTA, were all of the units on the BSD powered? Did you check voltage between the block and the + terminal in the engine bay?

Where on ISTA can I find this info, and also no I have not, I do have a multimeter on hand tho

[e91Owner]

Originally Posted by 3azy92

Where on ISTA can I find this info, and also no I have not, I do have a multimeter on hand tho

You said you diagnosed it with ISTA. When you diagnose it, it will bring up the tree with all of the components on the BSD.

[3azy92]

[QUOTE=e91Owner;29146250][QUOTE=3azy92;29146109]

Originally Posted by e91Owner

On ISTA, were all of the units on the BSD powered? Did you check voltage between the block and the + terminal in the engine bay?

Sorry I misunderstood the question, but the DME, CAS, and FRM show up on the tree with fault memory. Also I'm getting 12.2 on the voltage reading

[gbalthrop]

Originally Posted by 3azy92

... the DME, CAS, and FRM show up on the tree with fault memory. Also I'm getting 12.2 on the voltage reading

You ought to be able to figure out what the issue is if you use ISTA correctly. Attached is a PDF: "Fault Memory & Test Plan", that explains HOW to view, SAVE & Post ScreenPrints of your DME Fault Codes, including the "Description" and "Details" Tabs that offer further insight than simply providing Fault Codes.

I'm NOT sure where/how you got the idea that "2E7C" fault code suggests you might need to replace the DME. The ISTA Definition for that code is:
"DME: BSD Interface Signal, or BSD data bus communication fault"
The BSD (Bit-Serial Data) bus connects the DME to the IBS (Intelligent Battery Sensor), OZS (Oil Condition Sensor), Alternator & Coolant Pump.

This will take Multiple Steps, to get proper diagnosis over the Internet, but you/we will ALL learn something if you just take the time to do the steps in order, and SAVE/POST the ISTA ScreenPrints suggested. See part VIII on the last page of PDF for HOW to save and post screenprints.

FIRST STEPS Suggested:
1) Follow the steps in the pdf, I through V;
2) Step III is "Display Fault Memory"; Save and Post ScreenPrint of Fault Memory screen;
3) Step IV is "Description" Tab display of selected fault code; display and SAVE ScreenPrint of Description Tab for each DME Fault;
4) Step V is "Details" Tab display of selected fault code; display & SAVE ScreenPrint of Details Tab for each DME Fault, as above.

Go that far for now and Post ScreenPrints as attachments to your next post, and we can suggest "Next Steps".
George

[3azy92]

Originally Posted by gbalthrop

You ought to be able to figure out what the issue is if you use ISTA correctly. Attached is a PDF: "Fault Memory & Test Plan", that explains HOW to view, SAVE & Post ScreenPrints of your DME Fault Codes, including the "Description" and "Details" Tabs that offer further insight than simply providing Fault Codes.

I'm NOT sure where/how you got the idea that "2E7C" fault code suggests you might need to replace the DME. The ISTA Definition for that code is:
"DME: BSD Interface Signal, or BSD data bus communication fault"
The BSD (Bit-Serial Data) bus connects the DME to the IBS (Intelligent Battery Sensor), OZS (Oil Condition Sensor), Alternator & Coolant Pump.

This will take Multiple Steps, to get proper diagnosis over the Internet, but you/we will ALL learn something if you just take the time to do the steps in order, and SAVE/POST the ISTA ScreenPrints suggested. See part VIII on the last page of PDF for HOW to save and post screenprints.

FIRST STEPS Suggested:
1) Follow the steps in the pdf, I through V;
2) Step III is "Display Fault Memory"; Save and Post ScreenPrint of Fault Memory screen;
3) Step IV is "Description" Tab display of selected fault code; display and SAVE ScreenPrint of Description Tab for each DME Fault;
4) Step V is "Details" Tab display of selected fault code; display & SAVE ScreenPrint of Details Tab for each DME Fault, as above.

Go that far for now and Post ScreenPrints as attachments to your next post, and we can suggest "Next Steps".
George

UPDATE*

I'm not sure if I can post a article from a website explaining exactly what BSD is and how it works. If I can someone please let me know so I can put it up on here. But in that article, it explains how the Electric Coolant pump, Oil level sensor, Alternator, and Intelligent Battery Sensor is connect via the BSD and if I am getting the 2E7C (BSD data bus communications fault) code, I can work backwards and disconnect these 4 things to see if there is a difference within the fault readings on ISTA. I disconnected the IBS and Alternator being the easiest to access, and sure enough!!!! The 2E7C code went away and showed the IBS and Alternator disconnected. Plugged the the IBS sensor and everything went to $#!+ again. The IBS was faulty and was throwing everything off.

Question - if I remove the IBS will that still stop the car from turning on?

[e91Owner]

[QUOTE=3azy92;29152631][QUOTE=e91Owner;29146250]

Originally Posted by 3azy92

Sorry I misunderstood the question, but the DME, CAS, and FRM show up on the tree with fault memory. Also I'm getting 12.2 on the voltage reading

That's good, but not the diagram that I was referring to. When you run the diagnostic for your BSD DTC, it will bring up the BSD circuit and show you all of the items (alternator, IBS, etc.). My gut tells me it's probably the IBS since it's such a common problem. Without a lengthy diagnosis, you can always just unplug it and see if the car starts. To answer your later question—yes the car will start without the BSD plugged in. Many people just leave it unplugged without replacing it.

[gbalthrop]

Originally Posted by 3azy92

... I disconnected the IBS and Alternator being the easiest to access, and sure enough!!!! The 2E7C code went away and showed the IBS and Alternator disconnected. Plugged the the IBS sensor and everything went to $#!+ again. The IBS was faulty and was throwing everything off. Question - if I remove the IBS will that still stop the car from turning on?

Maybe it's just me, but I'm have trouble following exactly what you did. My best understanding is that you disconnected the BSD Connector at the Alternator, and also SOMETHING at the IBS. There are TWO (2) Connectors related to IBS wiring:
1) Single Red wire in black sheath that goes to LARGE Blue connector plugged into Center-Rear of Rear Power Distribution Panel, on top of the battery. That provides battery B+ signal to the IBS so it can measure Voltage;

2) Two-wire connector, also blue but smaller, (three pins but 2 wires) that is the BSD wire and a KL15 Wakeup wire to/from the IBS, connector to chassis wiring harness above & outboard of the battery.

Questions:
A) WHICH of those two IBS connectors did you disconnect?
B) Before you disconnected one/both of those connectors, Starter Cranked engine, but engine would NOT fire?
C) Disconnecting ONE/BOTH of those connectors allowed Engine to fire when cranked?
D) What is NOW disconnected, and does engine start/run NORMALLY?
E) What fault codes do you NOW have with whatever is NOW disconnected? Is LAST ISTA Screen Photo attached to your Post #9 the current Fault Memory List?

Your IBS MAY/may NOT be faulty. You MAY have a fault in the KL15 Wakeup wire. You already Effectively/Electrically REMOVED the IBS by disconnecting whatever you disconnected. That disconnection AT LEAST corrected the BSD line Fault (assuming your Alternator BSD connector has been RE-Connected).

There is NO reason to physically REMOVE the IBS from the vehicle. WHY disconnecting whatever you disconnected worked to allow engine to fire depends upon WHAT you disconnected. Disconnecting EITHER IBS blue connector will prevent the IBS from working as intended. However, AFAIK, the Alternator will/SHOULD revert to a "Default" Voltage output, in range of 13.8V to 14.0V (you can measure that with DMM or ISTA Live Data), and keep your Electrical System & battery functioning at a nominal level (probably NOT "Optimal").

We would like to help, but we need to know details of what was done. Otherwise, we may just be spreading MIS-information.
George

[dpaul]

Originally Posted by 3azy92

UPDATE*

I'm not sure if I can post a article from a website explaining exactly what BSD is and how it works. If I can someone please let me know so I can put it up on here. But in that article, it explains how the Electric Coolant pump, Oil level sensor, Alternator, and Intelligent Battery Sensor is connect via the BSD and if I am getting the 2E7C (BSD data bus communications fault) code, I can work backwards and disconnect these 4 things to see if there is a difference within the fault readings on ISTA. I disconnected the IBS and Alternator being the easiest to access, and sure enough!!!! The 2E7C code went away and showed the IBS and Alternator disconnected. Plugged the the IBS sensor and everything went to $#!+ again. The IBS was faulty and was throwing everything off.

Question - if I remove the IBS will that still stop the car from turning on?

Think about 2A77 and 2A3F. Stop thinking about BSD, at least for now. There is no BSD failure mode that will prevent the engine from starting.

[gbalthrop]

Originally Posted by dpaul

Think about 2A77 and 2A3F. Stop thinking about BSD, at least for now. There is no BSD failure mode that will prevent the engine from starting.

Your understanding of OP's Posts obviously DIFFERS from mine.

Actually, there have been MULTIPLE claims/posts that disconnecting IBS allowed Engine Crank/Start where there was NONE BEFORE disconnect. NO ONE has taken the time to address the details and explain WHY. Perhaps if OP, who has ISTA, will do that in THIS CASE, we can learn WHY.
George

[dpaul]

1) there are multiple claims that unplugging the IBS can allow a car that would not start to suddenly do so. They make no sense. You understand electricity as well or better than I do - make sense of the IBS claims if you can.

2) Not sure what you mean about differing understanding of the OP’s post. In post #1 he says his car cranks but does start. He says his only codes are the BSD code and one non-diagnostic CAS code. After you ask for a screen print, all of a sudden he has valvetronic codes very likely the reason his car does not start

[dpaul]

3) for the sake of completion - yes there is an obvious IBS failure mode which will prevent the car from cranking but will also affect multiple systems - the IBS introduces a very low resistance in series with the negative cable. The flow of current through this low resistance results in a very small voltage drop which is measured and reported to the DME. If the "low-resistance" element of the IBS should open, no current can flow and no cranking will happen. Still, simply "unplugging" the IBS (removing its connection to the BSD bus), cannot affect starting.

[e91Owner]

Originally Posted by dpaul

3) for the sake of completion - yes there is an obvious IBS failure mode which will prevent the car from cranking but will also affect multiple systems - the IBS introduces a very low resistance in series with the negative cable. The flow of current through this low resistance results in a very small voltage drop which is measured and reported to the DME. If the "low-resistance" element of the IBS should open, no current can flow and no cranking will happen. Still, simply "unplugging" the IBS (removing its connection to the BSD bus), cannot affect starting.

It's not the IBS that is preventing starting, per se. It's the BSD. The IBS faulting the BSD so that communication along it is not possible seems to be the result based on many, many posts on this issue. Why that is, is another story, but most people that come here and drop a question on a multiple owner 10+ year old car are probably more interested in it running than running perfectly. Since the IBS being missing at worst will affect battery life, it seems most leave it unplugged and move on. Me personally, I would just replace the IBS. It's not that expensive at about $120 for an OE part from FCP ($87 at rock auto).

[gbalthrop]

I'm NOT trying to impugn ANYONE'S knowledge here, particularly dpaul or e91Owner. I was trying to be humorous, as I interpreted OP's LAST post (Post #9) as suggesting (although NOT stated) that the engine fired & started with the "IBS disconnected", whatever connector that referred to.

I would like to know WHY disconnecting the IBS (somewhere ;-) allows Starter to Crank or Engine to fire when cranked, where that did NOT happen before disconnection. I do NOT pretend to know any more than you do. I just want to know OP's DETAILS, so MAYBE we can learn something.
George

[dpaul]

Originally Posted by e91Owner

It's not the IBS that is preventing starting, per se. It's the BSD. The IBS faulting the BSD so that communication along it is not possible seems to be the result based on many, many posts on this issue. Why that is, is another story, but most people that come here and drop a question on a multiple owner 10+ year old car are probably more interested in it running than running perfectly. Since the IBS being missing at worst will affect battery life, it seems most leave it unplugged and move on. Me personally, I would just replace the IBS. It's not that expensive at about $120 for an OE part from FCP ($87 at rock auto).

If your hypothesis is true, then if the OP disconnected the IBS, his engine should start.

If it is true, I'll buy you a beer.

So, OP - did unplugging the IBS allow the car to start?

[gbalthrop]

Originally Posted by dpaul

... So, OP - did unplugging the IBS allow the car to start?

AND, WHICH Connector did you "unplug"???

[e91Owner]

Originally Posted by dpaul

If your hypothesis is true, then if the OP disconnected the IBS, his engine should start.

If it is true, I'll buy you a beer.

So, OP - did unplugging the IBS allow the car to start?

I dunno man. It works all the time. For whatever reason, that simple part seems to wreak havoc on the BSD when it goes bad. I'll be interested to see if the same is true here as well.