[HugoCountsto7]

Thread Closed

[maxoutput]

Definitely not related to a faulty IBS? I wouldn't imagine you could have but is it possible both alternators have faulty voltage regulators?

[galahad05]

This may be neither here nor there, but wasn't there a sometimes faulty output transistor that goes bad on a few ECU boards? This was like a 50 cent fix (if you know how to solder/desolder).

[galahad05]

Oh, search turned it up--it was one of the transistors driving a coil/plug.

http://www.e90post.com/forums/showthread.php?t=734162

[galahad05]

OP, check this out:

http://www.bmw-planet.net/diagrams/r.../e90/index.htm

They have wiring diagrams and explanations. I think their browser app may require internet explorer (how quaint).

FYI:

BSD interface to the alternator

The alternator with BSD interface can actively communicate with the engine control unit. The alternator is not linked to the charge indicator lamp, only to the engine control unit. The alternator can detect a variety of faults.
Function

The following functions have been implemented in the engine control unit for the alternator with BSD interface:
-Activating/deactivating the alternator on the basis of appliable parameters
-Specification of the maximum permitted degree of utilisation of the alternator
-Control of the alternator's load response
-Calculation of the alternator moment degree of utilisation
-Diagnosis of the data line between the alternator and the engine control
-Filing of alternator faults in the defect code memory
Activating the load control lamp in instrument cluster via CAN
In comparison to alternators used so far, the display strategy of the load control lamp does not change when the alternator with BSD interface.
The basic function of the alternator is also ensured if the communication between the alternator and the engine control is interrupted.
Possible faults

The following possible faults can be distinguished from fault entries:
High temperature control: The alternator is overloaded; to be safe, the alternator voltage is reduced until the alternator has cooled down again. The charge indicator lamp does not light up.
-Mechanical fault: The alternator is mechanically blocked or the belt drive has failed.
-Electrical fault: Exciter diode defect, excite interruption, overvoltage due to controller defect.
-Communication failure: Line defect between the engine control and alternator.
The following cannot be detected: Coil interruption or short-circuit
Battery charge indicator lamp

The signal for the charge indicator lamp to light up is transferred across CAN to the instrument cluster. The charge indicator lamp lights up if there is mechanical and electrical fault (see above).
Detection

The above-mentioned calculation of the alternator moment and the rate of utilisation of the alternator are heavily dependent on the type (performance) and manufacturer.
This is why the alternator provides the engine control with this data. The engine control adapts its calculation and set values to the exact type.
Aim

The precise calculation of the alternator moment and control of the load response function enables good idling of the engine.
Control of the alternator voltage based on nominal values from the engine control enables a good charge balance of the battery.
__________________

[HugoCountsto7]

Originally Posted by maxoutput

Definitely not related to a faulty IBS? I wouldn't imagine you could have but is it possible both alternators have faulty voltage regulators?

This car was built without an IBS. I forgot to mention that. It was one of the first things I asked when I got to the independent workshop yesterday. What they told me was that the ECU is also deciding some of the voltage output (controlling/communicating directly with the voltage regulator on the alternator through the cable we unplugged.)

[HugoCountsto7]

Originally Posted by galahad05

The basic function of the alternator is also ensured if the communication between the alternator and the engine control is interrupted.

^ This is what is allowing me to get around now.

I don't see anything in this description about the battery not being charged due the data link being removed.

[HugoCountsto7]

Old

[galahad05]

DL, I never noticed: did you actually measure the voltage at your battery, all-off, acc-on, and engine running?

This with the alternator in failsafe (unplugged control) mode.

[galahad05]

Have you also tried temporarily heat shielding the ECU? See if this makes a difference in the time it takes to go bonkers.

Reason: I want to see if it REALLY is something to do with the ECU.

So I'm assuming based on your graphs and such that the OBD port is working. That implies a LOT of the ECU is working correctly. Maybe the signal driver for the control/communications lead to the alternator is flaky? As in, you're seeing thermal expansion causing intermittent solder joint failure in the signal driver.....

[HugoCountsto7]

Originally Posted by galahad05

DL, I never noticed: did you actually measure the voltage at your battery, all-off, acc-on, and engine running?

This with the alternator in failsafe (unplugged control) mode.

Yeah, I've been checking the voltage thru the ECU with the Deep OBD app and with a multimeter at the battery and the alternator for some months now. Measuring directly at the battery terminals:

From resting overnight (pre-waking up from sleep mode): 12.65 V
Post-waking up from sleep mode (unlocking doors with fob): 12.45 V
Key in ignition (systems waking up but engine not running): 12.35 V
Engine running (A/C is off): 14.11 V
Engine running and A/C on: 14.03 V

[galahad05]

Battery is good then, and well-charged. It may very well be the ECU or the comm module of the alternator.

You did say you swapped alternators already right?

[HugoCountsto7]

Originally Posted by galahad05

Battery is good then, and well-charged. It may very well be the ECU or the comm module of the alternator.

You did say you swapped alternators already right?

Yep, alternator has been swapped and the battery also. the 16 Volt spike only occurs when engine temps have plateaued.

Could it be something with the cooling system? Like a bad winding in the radiator fan, and when it tries to kick in it causes issues?

I ordered some insulating foil last night. Should arrive this week. I'd like to protect the ECU and the ABS Modules.

[galahad05]

Now keep this in mind: you normally SHOULDN'T NEED to insulate your ECU box. There are thousands of these cars driving around without problems, with uninsulated ECUs.


This is a test, to see if it is truly ECU-heat related.


By the way, did you manage to take a very close look at the ECU board around the driver for this line to the alternator?



As for your fan winding question: sorry man I'm not really certain, but it DOES look like something in the ECU isn't right.

Because the ECU seems to be working (more or less), I still suspect the actual driver interface IC to/from the alternator.
I wonder if I could dig up an ECU motherboard diagram....

[galahad05]

Also, I cannot believe that there aren't any stored shadow codes from all this. What were the codes?


BTW, I found my Bentley manual ('06 + models). I'm trying to make heads or tails of this. Stand by.

[galahad05]

[galahad05]

If it IS the DME, take a look at these sites (may be useful).

http://www.team-bhp.com/forum/techni...-3-series.html

http://www.bimmerforums.co.uk/forum/...81/index3.html

[HugoCountsto7]

Wow thanks for the scanned document and the forum links.

[HugoCountsto7]

Originally Posted by galahad05

Also, I cannot believe that there aren't any stored shadow codes from all this. What were the codes?

When I check the codes with Deep OBD:
4A56 Power Management (Currently Active)
4660 Supply Voltage (Not Active, and older)
4A17 Alternator (Not Active, and older)
A few glow plug errors which are not active

[galahad05]

Originally Posted by DLoBrown

Wow thanks for the scanned document and the forum links.

One of the first things I checked 2 weeks ago was the conditions inside of the ECU (tupperware looking) box. It was clean and dry inside there. No evidence of water having been in there or on the ECU casing. I tried to get the ECU to slide out that day, but I couldn't get the wire harness to come loose from the ECU connector. So I put everything back in a locked it up. This as far as I've gone in the ECU direction.

The car has still been running fine without the BSD link connected to the Alternator. Besides the two warnings (with voltage spikes) that I got on Saturday, I have not had any other problems. Both of those spikes were accompanied by the trifecta warnings (ABS, DTC, Tire) Then again, I haven't driven far or let the car heat up idling this week.

Today the insulation came in the mail so I wanted to let the car heat up, and maybe cause the fault, first. I was also curious to see if I could feel heat building near the ECU or the ABS module. To do this I removed the engine bay's ECU black cover and the nearly identical black cover for the ABS module. These are the two covers witch just snap on near the windshield.

I wasn't sure if it was caused by the covers not trapping heat into those module bays/housings, but I never had a single voltage spike or warning. I even closed the black covers after a while and never saw a fault. I think I had the car running for nearly an hour, and at least 25 minutes of that would have been near 90 deg C engine temps. I finally gave up and pushed some of the insulation between the ECU's housing (tupperware container) and the black casing that box it is within. I also pressed some of the insulation behind some rigid lines close to the engine bay wall just on the other side of the ECU housing and container. I could feel a lot of heat there coming from the DPF and the oil re-breather.

I even tried shaking as many major positive and ground wires as possible. The connection as the starter looks good and tight. All the grounds I can see look tight. The positive connection inside the ECU housing (coming directly from the battery) looks good and tight.

So, I'm kinda stuck now. I guess I need to repeat all of this with the BSD link plugged into the alternator?

Yes, connect the problem control link, see if / when the problem occurs.


Before that though, make sure via shadow code scans that the ECU/DME is working okay and not throwing codes (this with the problem control line still disconnected between the alternator and the DME).

Well....actually, you SHOULD at least see some sort of "I can't see the Alternator's BSD connection working" code. Because of it being unconnected and everything....
But, you shouldn't be seeing any other codes.

[HugoCountsto7]

Originally Posted by galahad05

Before that though, make sure via shadow code scans that the ECU/DME is working okay and not throwing codes (this with the problem control line still disconnected between the alternator and the DME).

Well....actually, you SHOULD at least see some sort of "I can't see the Alternator's BSD connection working" code. Because of it being unconnected and everything....
But, you shouldn't be seeing any other codes.

I scanned for shadow codes at lunch today, and found none (empty list). However, under the normal FS_Lesen I do have a new Generator-Layer-BSD failure which in the details it lists that there is no communication through the BSD. Code is 4A07.

All failures:
4222 - Glow plug cylinder 2
4232 - Glow plug cylinder 3
4242 - Glow plug cylinder 4
4A27 - IBS sensor (I don't have an IBS sensor)
4587 - Fuel Filter (this one is new to me, haven't seen until today)
4C03 - Botschaft
4660 - Supply Voltage
4A67 - Powermanagement Bordnetz
4A07 - Generator BSD

[galahad05]

So, as far as the DME is concerned, there's no problems anywhere except for the one thing you did, disconnecting the BSD 9.5k wire between the alternator and the DME.

And the entire car seems to be running fine.



Bet things will go bad when you reconnect that wire....
This really tells me there's something going on, on that DME motherboard, around the area where the BSD transceiver is.

This was why I was suggesting you look closely at that area. On the off chance that you can see something sort-of obvious around there on the board (loose connection, obviously bad solder joint, etc.).
This way, you have a shot at fixing that one cheap thing on the board, instead of shelling out the big bucks to replace the entire unit.

What the heck, if you have to have them replace the board any way, why not try a repair on that thing first? Assuming you see something to replace.




tl;dr:
Previously, I'd pretty much assumed that the problem was IN the DME, but was hoping that there was a way to repair it on the cheap instead of replacing the entire board (and recoding it at the dealership/service center).