Rescued a 2001 750IL with issues...

[SilverIris]

After the ordeal called door reassembly yesterday, I wanted to do some small things. Pulled the fuel door actuator and found its cable was broken. No big deal, I just acquired a known perfect actuator the day before. Wrangle a coat hangar from the fuel door side int the trunk, tape the cable on and give it a pull? Car says nope, you're pulling the hangar off every time... And it took about 7-8 attempts to get the hanger to poke through in the proper location. There was some swearing after the 4th pull attempt.

So I hopped on Youtube and found that the bushing/sleeve has to be removed to feed the cable through. And when the sleeve broke, there was more swearing. Fortunately, it broke in a way that made it still reusable. Not the prettiest, but it does its job. Reassemble everything, and it worked!

Time for a break now. 2 minutes later, new fog lights are in.

The whole process gave me an idea. Since the actuator I pulled from the 750IL worked fine (just had a broken cable), I was gonna swap it into my 740I and kill two birds with one stone. On a whim, I tested what was already in the car with the leftover pigtail ran straight to the battery and...IT WORKS! Suddenly, I feel very relieved that I don't have to go through that bit of left-handed hell again. Seriously, you HAVE TO either be left handed to do this or be Chuck Norris, although I'm pretty sure he would just glance at it and the parts would assemble themselves out of fear...

Okay, back to my 740I now. Fuel Door Actuator works properly. Multimeter comes out and I lock/unlock the car several times. Unlock shows up perfect, Lock has a weak 12v+ pulse (2v give or take). Hop on NewTIS (whoever runs this site, you are AWESOME!!!), it's just wired in parallel to the rear door actuators. Diagnosis is Voltage Drop that only appears on this actuator for ~1 second when locking (short circuit to ground probably), two ways to fix it:

Option 1: Rip apart the whole interior and dig through the harness, testing for continuity to ground at each connection all the way back to the ZKE
Option 2: Retrofit two SPDT relays, triggered by ground signal from the stock wiring and run a fresh power and ground feed, ala RX-7 Power Window Relay Mod. Pretty common scenario when it comes to wiring reversing dc motors such as lock actuators from scratch. Google if you need a diagram.

But this situation requires a small change from the standard diagram commonly found on the net. Certain Mazdas like the Eunos Cosmo and 89-92 MX-6/Probe use a One-wire trigger in this manner, they just use a resistor on one trigger to differentiate the signals from each other. Since our lock signals are clear 12v+ and Ground, anyone with the right electrical knowledge can figure it out. I just did it in my head as I'm writing this.

Anyway, enough tangents for now. Now that the easy sidequests are done, back to the restoration. Next time, parasitic draw part 2.

[SilverIris]

Since parasitic draw testing is a major drag, I'm tackling the electronics/cluster issues from before: dead tachometer and temperature pegged to Full Hot

Digging around on NewTIS yielded a straightforward understanding of the Coolant Temperature circuit. It's akin to a Mazda RX-7's system, but with the two sensors "combined" into one housing.

The sensor has two independent sensing elements, one for the temperature gauge and one for the DMEs (DME1 to be precise) as follows:
Coolant Temperature Circuit diagram:

Coolant Temperature Sensor pin 1------IKE Cluster pin 19 (Connector X10114)

Coolant Temperature Sensor pin 2------IKE Cluster pin 18 (Connector X10114)
Coolant Temperature Sensor pin 3------DME1 pin 24*

Coolant Temperature Sensor pin 4------DME1 pin 25* [*DME#1 Connector X60103 pins 21 and 22]

I'm not 100% certain which DME pins it is a straight line to, due to mixed information in NewTIS. Clarification is much appreciated here


In 2012, I built a diagnostic center for bench testing gauge clusters by mapping out their sensor values and reconstructing their ranges with an Arduino, some potentiometers, a keypad and a square wave signal generator.

Since temperature sensors are resistors whose impedance changes with temperature (GM/Delphi graphs the data on all of their sensors, Google for more info), spiking the meter one way or the other denotes either no resistance (0 ohms, seems unlikely) or Infinite resistance (infinite Ohms, AKA burned the internal element apart), depending on how the sensor is scaled. I'm sure a datasheet is floating around the net somewhere, but I've yet to dig it up.

As for the Tachometer, it is a bit murky how the DME(s) receive the information, but it is output on DME1 X60104 pin 17/DME2 X60204 pin 17 to the Cluster (IKE) at X10114 Pin 3 (TD signal). It is also found at the Under Hood Diagnostic Connector (X6002, Pin 1). Tomorrow morning, I'll see if it's outputting data there.

[a777fan]

Good stuff so far. I’m enjoying the detailed report outs.

On the temp sensor, it seems like a quick unplug of the sensor will tell you how the system works. Once you have confirmed the circuit ‘open’ observe the gauge and you’ll have your answer.


Sent from my iPhone using Tapatalk

[Timm]

A common failing for the temperature gauge is the heater for the characteristic-mapped thermostat - on the 740i at least, the looms for the heater and the temperature gauge are entwined, and when the heater fails its loom melts into the gauge loom which pokes it into the red. Pictures here:

https://www.meeknet.co.uk/e31/BMW_M6...e_Problems.htm

[SilverIris]

I'll definitely keep that in mind. But onto other stuff now...

I've been busy for the past few days, clearing out my laptop and desktop computers for a much-needed reorganization of my files into the appropriate folders I set up almost a year ago. Time well spent as it eliminated almost 30gb of duplicate files spread over 3 different partitions.

Before that, I went on eBay and bought a few things...

PA Soft/BMW-Scanner v1.4.0 cable for $12, K+DCAN Cable with 7/8 pin switch for $15 and a a set of new stainless steel brake hardlines for my Expedition. With space cleared, I gave my laptop the apparently-famous "Mike's Easy BMW Tools" package and started acclimating myself to how things work. Also tried playing around "Dr.Gini", but it doesn't want to work. Keeps asking for Microsoft .Net 4.030319, even though it's already installed. So I tried reinstalling .Net and repeatedly fails with Fatal Error code 0x80070643. Anyway, moving on now.

This morning, I cracked open the brake line box and found one of the Master Cylinder to ABS Control Unit lines was bent incorrectly on one end, so the fitting faces the wrong direction. On top of that, my 740I's battery was down to 5.8v (from sitting for a few weeks, key on a few times). It's back on the charger now. The plan is to get my feet wet by exploring the coding data/information on my 740I to establish correct behavior and procedures as a baseline before jumping in on the 750IL. That way, I know how to make it behave properly and can ask appropriate questions in the Diagnostic Section if need be.

Just to cover all bases, I've been reading this thread: https://www.bimmerforums.com/forum/s...=cluster+donor

"Engine speed display
Since 5/97 an instrument cluster has been phased-in which features the plugged-on instrument cluster electronics (IKE) integrated in the display unit (AE). This instrument cluster can replace older instrument cluster versions.
The instrument cluster uses the engine speed signal from the engine control unit (td for petrol engines) to determine the engine speed. Adaptation to the various types of engines uses the stored coding data.
In the case of the integrated version of the instrument cluster, phased-in as from 5/97, the coding data defines whether the engine speed signal is routed via the CAN bus or via a separate line to the instrument cluster.
From terminal 15 "ON", the engine speed instrument (rev counter) is controlled by the instrument cluster electronics (IKE) with the corresponding engine speed signal. The speed information is also made available on the instrumentation bus (I-bus) and body bus (K-bus) for other control units."

"Coolant temperature display
Since 5/97 an instrument cluster has been phased-in which features the plugged-on instrument cluster electronics (IKE) integrated in the display unit (AE). This instrument cluster can replace older instrument cluster versions.
The instrument cluster determines the current coolant temperature from the coolant temperature sensor (NTC resistor). The coolant temperature sensor is connected by means of its own ground (analog ground) and sensor line (analog positive) to the instrument cluster electronics (IKE).
In the case of the integrated version of the instrument cluster, phased-in as from 5/97, the coding data defines whether the coolant temperature signal is routed via the CAN bus from the engine control unit or via a separate line from the coolant temperature sensor to the instrument cluster. The instrument cluster electronics (IKE ) transfers the "coolant temperature" information via the instrument bus (I-bus) and body bus (K-bus)."

While I don't think it will be necessary to replace the IKE cluster as it passed the self-test, but it appears that all post 5/1997 E38 clusters are physically identical, with any visible differences being a result of coding. But it is good to know for the worst-case scenario.

[SilverIris]

So I received my BMW-Scanner today. Followed the directions, installed the drivers and it works. One thing you NEED to know is that doing a Bench Test makes a "Hardware Faulty" message pop up if you are NOT plugged into the car. This is because the electronics in the box are powered by the car, NOT the computer. The cable and box are good, so learn from my mistake.

Took a scan of my 740I as a baseline, then did it on the 750IL and much was learned. On the 750IL, the cluster was improperly replaced with one from #DD73905, which also had its cluster replaced in November 2006 (46/06 in log file) before its demise in December 2013. This explains the higher mileage and Tamper Dot. This overwrote what was stored in the EGS (Transmission control) and EWS (alarm/drive-away protection) modules with a considerably higher value, but our good friend the LCM (Light Control Module) kept the correct reading exactly as Timm described on Meeknet.
Conclusion: Timm was right all along

Also discovered that the LEW (Lateral Acceleration sensor) was pulled from the same donor car as the cluster, but has the proper build date...weird.

A big thank-you to Timm for being the E38 Messiah and this site for the acronyms to properly understand what Timm is referring to:
https://www.bmwsections.com/info/abbreviations.php

During the scan, both cars reported a considerable number of errors. While this was done, the 740I's battery had just been reinstalled with a full charge, while the 750IL's batteries were exceedingly low (3.5v on bottom, 5.8v on top battery) and being charged at 2A. Neither engine was running when it was connected to the scanner. It stands to reason that the voltage readings may have produced some of these error(s)

One such error is on the 740I's IKE (cluster), for Internal fault/EEPROM checksum/coding incorrect or incomplete. Cluster was replaced and odometer matched properly in December 2003 (presumably under warranty/BMW Goodwill program). Now I know why my cluster has no dead pixels...

With all of that said, I've requested that Timm review the log files for both cars as he is much more capable of identifying issues that might not be obvious to someone as green as I am. Errors such as Rear Fog Lights showing up in both logs has me wondering if I'm overlooking something important.

Overall, the $12 Ebay pricetag for a BMW-Scanner 1.4.0 has earned its weight in gold already and I would definitely recommend new owners buy one.

[georgebest]

Overall, the $12 Ebay pricetag for a BMW-Scanner 1.4.0 has earned its weight in gold already and I would definitely recommend new owners buy one.

That software is amazing, saves you so much time reading all modules with one click.

[masbury]

Do yourself a favor. Put a 10amp+ charger on the under-hood jumper posts while you are running diagnostics on the car. The car needs to be at full charge while you are farting around reading codes. If you keep discharging your batteries, you will be replacing them. 2 amps doesn't cut it.

Good luck

[SilverIris]

Excellent point masbury, I just set the charger at 2A to raise the voltage enough to get it to read and establish a baseline for the car. A proper diagnostic session requires more than that. I have reason to believe that the 55AH top battery is weak and draining the 110AH bottom battery due to how the Disconnect Switch operates. Top battery voltage reads low, car triggers the Disconnect Switch to link both batteries in parallel, then the Top battery acts like a parasite and pulls the Bottom battery right into the ground. Just like my ex-fiancee...

I'm putting together a "Your First Coding Session" guide that spells out the whole process in distinct, clear steps that anyone can understand. Your charger suggestion is now in the guide as a precaution to avoid Catastrophies of the Divide By Zero Caliber

Do you happen to know what the "ADFG" is? The guide has a chart that deciphers common acronyms from their German abbreviations into full German words, an English translation and a Plain English explanation that new owners can understand. My present understanding is that ADFG is short for "Alle Daten Fahrgestell" (All Data Chassis in English) or "Aufbauen Daten Fahrgestell" (Assembly Data for Chassis in English), but I may be wrong about this. Based on what came from my 740I's log, it appears that certain modules have the last 4 of the car's VIN number, while others appear to have no rhyme or reason associated with this information. Any help is much appreciated.

[masbury]

No, I'm sorry I can't help you with your translations. There are people here way more knowledgeable than me about these cars and the German language.

I only speak 3 languages...bad English, car and swear. The last two are generally used together.

Mike

[SilverIris]

No, I'm sorry I can't help you with your translations. There are people here way more knowledgeable than me about these cars and the German language.

I only speak 3 languages...bad English, car and swear. The last two are generally used together.

Mike

From playing around with the Eunos Cosmo wiring diagram book, I learned that most of what's in a car needs no understanding of the language in question. A throttle sensor is still a throttle sensor, even if it reads スロットル センサ (su ro- ta ru se n sa) or Drossel klappen sensor (throttle position sensor in German). They still have a 5v VRef (shared with manifold pressure sensor and a few others), ground (obvious) and 0-5v output, no matter what language it's in.

Same thing applies with ADFG. If we know what it's used for, I can reverse-engineer what it means, even in German.

[SilverIris]

Tach is dead and Temperature gauge is pegged.

After the Battery Bork a few weeks ago (my fault, tried installing backwards...) the Tachometer and Coolant Temperature Gauge started acting strangely. Between this and recently learning that the IKE's M35080 chip CANNOT be reprogrammed in PA Soft to correct the Odometer, it's time to start reading up on disassembly.

So last night, I hopped on Youtube and found this:
https://www.youtube.com/watch?v=58EyC0hXYFg&t=2937s

In this video, the cluster is bench tested and I saw that the Temperature Gauge behaves identically (immediately goes to Full Hot) to what's happening in the 750IL. A logical assessment is that it is from lack of a Canbus signal, which PA Soft reports is how Tachometer signal and Coolant Temperature are delivered to the IKE on the 750IL.

Bus Topology I -K-M-P-Can-Diagnostic.jpg

Devices on the Canbus network are the IKE, LEW (Steering Angle), DSC (ABS/Stability Control), DME (Engine Control) and EGS (Transmission Control). Since the car starts, idles and revs with no fuss, the DME(s) internal functions are working as they should to receive signals from the appropriate sensors (Crank Angle and Cam Angle sensors?) and translate this info Engine RPM.

Here's the last PA Soft error log from the car (10/1/2019):

# ERRORS DETAILS - DTC(hex)/PARAM(hex)
---------------------------------------------------------------------------------------------------------------------------
DME -> D7/D4 - CAN-Timeout DME
Shadow-memory:
6C/02 - Permanent supply
D9/D4 - CAN-Timeout EML
EC/D4 - CAN-Timeout EGS
D8/C4 - CAN-Timeout ASC/DSC
D7/D4 - CAN-Timeout DME
13/54 - CAN-Timeout EKAT
06/D4 - CAN-Timeout IKE
94/84 - Wire fault DWA/EWS Input (Short circuit or Interruption)

DME2 -> D7/D4 - CAN-Timeout DME
Shadow-memory:
6C/02 - Permanent supply
D9/D4 - CAN-Timeout EML
EC/D4 - CAN-Timeout EGS
D8/C4 - CAN-Timeout ASC/DSC
D7/D4 - CAN-Timeout DME
13/54 - CAN-Timeout EKAT
06/D4 - CAN-Timeout IKE
94/84 - Wire fault DWA/EWS Input (Short circuit or Interruption)
5B/54 - Tank ventilation valve Output

EGS -> 80/B1 - CAN-Bus check
93/01 - CAN Throttle valve
82/21 - CAN Timeout ASC
84/21 - CAN Timeout EML
81/31 - CAN Timeout DME

EWS -> 0F/FF - Power on reset
13/05 - Toleration of changing code increased, key 1
11/02 - Wrong password, key 1
10/01 - Wrong identification, key 1
0E/02 - DME changing code XOR-error
12/01 - Wrong changing code, key 1

ABS -> 1E/FF - Wheel speed sensor rear left, open circuit
38/FF - CAN Error
17/FD - Coding Error

LEW -> 10/8D - Watchdog
09/A9 - No CAN message (ASC)
0C/CD - CAN-Bus off
0B/CD - Wrong LWS-ID

SRS -> 12/88 - Fault lamp (AWL)
11/A0 - Power supply

IKE -> F0/C4 - CAN-bus off
F4/84 - No CAN message
FB/84 - No CAN message (EGS1)
F5/84 - No CAN message (ASC1)
F9/84 - No CAN message (DMEL4)

LCM -> 28/01 - Thermal oil-level sensor defect
Shadow-memory:
53/01 - Engine oil pressure
58/0B - Engine failsafe program
59/0F - Transmission failsafe program
5F/31 - Check coolant level
94/1C - Rear left fog light
95/1C - Rear right fog light

ZKE -> A4/21 - Mirror, potentiometer vertical or cable, driver's door
DC/05 - Steering column angle: communication error
31/21 - Wiper motor blocked, reset contact, wiper relay
49/01 - Wire WI1 or wiper relay 1, open circuit
4B/01 - Wire WI2 or wiper relay 2, open circuit
01/01 - Fuse power window rear
02/01 - Fuse interior lights
82/01 - Cable Tacho A (speedometer) or IKE missing
Shadow-memory:
93/3F - Power up from the GM III
80/02 - DWA-Alarm: Terminal R
72/21 - Cable Tacho A (speedometer) or IKE missing
89/02 - DWA-Alarm: hood/bonnet contact
85/01 - DWA-Alarm: door contact, rear, driver's side
94/22 - Power up from the driver's door module
95/22 - Power up from the passenger's door module
8A/21 - DWA-Alarm: tilt alarm sensor

NAV -> 01/00 - Navigation computer

BMBT -> 01/1F - Watchdog reset
0B/1F - Connector monitor UB, open circuit
03/12 - Radio status telegram timeout
16/0D - EEPROM Checksum does not match with programmed value

EML -> 86/B8 - Releasing error from main logic (error ECU)
00/00 - Error number 00
00/00 - Error number 00
00/00 - Error number 00
00/00 - Error number 00
00/00 - Error number 00
00/00 - Error number 00
00/00 - Error number 00
00/00 - Error number 00
00/00 - Error number 00

EDC -> 53/00 - Vcoil: Vcoil different to PWM -> control unit defective
63/00 - Valve error front: open circuit of both valve wires Soft
72/00 - Error number 72
75/00 - Error number 75
81/00 - Valve error rear: open circuit of both valve wires Middle
90/00 - Error number 90
95/00 - Error number 95
# SCAN END

I'm still pretty green to the whole Canbus system, but does this spell out which device(s) are mucking things up? If so, can someone please tell me.

[Timm]

The problem with bus systems (CANBus, I-Bus etc.) is that if a module holds onto the bus then all the modules can neither receive or transmit. The Instrument Cluster is able to connect to the modules on the CANBus via the Diagnostic Bus and is finding that all the modules that utilise CANBus are getting no data exchange. The problem is finding which module is holding onto the CANBus.

I think that your model has the star connection that joins all the CANBus lines together - it is a case of removing each of the modules in turn to see which module is causing the problem. Normally this would be the DSC module - and that can be simply disconnected at the module and then diagnostics can be re-run to see if all the other CANBus nodes spring to life. Your situation is different because you reverse-biased the electronics and that may have damaged any of the modules.

[SilverIris]

The problem with bus systems (CANBus, I-Bus etc.) is that if a module holds onto the bus then all the modules can neither receive or transmit. The Instrument Cluster is able to connect to the modules on the CANBus via the Diagnostic Bus and is finding that all the modules that utilise CANBus are getting no data exchange. The problem is finding which module is holding onto the CANBus.

I think that your model has the star connection that joins all the CANBus lines together - it is a case of removing each of the modules in turn to see which module is causing the problem. Normally this would be the DSC module - and that can be simply disconnected at the module and then diagnostics can be re-run to see if all the other CANBus nodes spring to life. Your situation is different because you reverse-biased the electronics and that may have damaged any of the modules.

Maybe it's because coffee hasn't taken effect and my Google-Fu hasn't fully loaded yet, but I'm a bit confused.
https://www.newtis.info/tisv2/a/en/e...faces/can-bus/

There are different application descriptors for each listed diagram: asc5, asc57, asc5d, NOT acc dsc3, dsc5, dsc57, acc me72kwp0, me72kwp1, ms420ds0

I keep seeing these pop up throughout NewTIS, but without a "hey, this is what they mean" article, it's just gibberish to me. The last three and other permutations in the same format seem to be the most common. But without a proper understanding, which diagram applies to the car in question?

[Timm]

They describe the systems fitted to your model - ASC (Automatic Stability Control), DSC (Dynamic Stability Control), ACC (Active Cruise Control - a very rare option!) - the last two are the software version of the DME and AGS. The identifiers denote the hardware version of each module.

The names CAN-H and CAN-L are the two physical wires of the CANBus system, Can High and Can Low. The bus is a differential system - it sits around 2.5V and one line pulses high as the other pulses low - noisy receivers such as the DME and EGS use both lines and differential receivers - other modules either use CAN-L or CAN-H, the data is identical, just inverted....

[SilverIris]

They describe the systems fitted to your model - ASC (Automatic Stability Control), DSC (Dynamic Stability Control), ACC (Active Cruise Control - a very rare option!) - the last two are the software version of the DME and AGS. The identifiers denote the hardware version of each module.

The names CAN-H and CAN-L are the two physical wires of the CANBus system, Can High and Can Low. The bus is a differential system - it sits around 2.5V and one line pulses high as the other pulses low - noisy receivers such as the DME and EGS use both lines and differential receivers - other modules either use CAN-L or CAN-H, the data is identical, just inverted....

That makes sense. It sounds like Canbus information can be viewed on an Oscilloscope in the same manner as fuel injector signal pulses, while the behavior is akin to a power lock actuator. With the wire colors being GE/SW (Yellow/Black) and GE/BR (Yellow/Brown), all that's left is to locate each piece of the system to isolate the one that's buggering up the system.

A6010 and A6020 DMEs: Under hood fuse box, under the cover
A7000 EGS: Same as DMEs
A65 ABS/DSC: On the ABS Control Unit, in front of the Brake Booster
A205 E-Cat Controller: Under Passenger seat carpet
R33 Steering Angle sensor: left-hand side of steering column (for LHD car)
A63 IKE Cluster: Blue connector for Cluster

Just for clarity, where is A144 (Active Cruise Control Unit) normally located? There's no mention of a location in NewTIS that I can find.

[Timm]

Probably do it with a volt meter - one module will be pulling either CAN-H or CAN-L to one of the rails....

[SilverIris]

Probably do it with a volt meter - one module will be pulling either CAN-H or CAN-L to one of the rails....

By that, you mean CAN-H would be pulled to 5v+ from 2.5v when receiving a message and CAN-L drops to 0v simultaneously?

Okay, next query. My apologies for the upside-down image, the forum uploader previews it correctly, then rotates it 180 degrees once it's uploaded.

20191005_180515.jpg

Where does one find the CAN-H and CAN-L wires for the DMEs in this mess? Also, isn't there supposed to be the aforementioned wires in the Diagnostic Connector? Every pinout I've found says they are there, but both of my E38s are missing Pin 3 (Can-L) Ideas on how to proceed?

[Timm]

The way forward is to slug your way around the TIS as this will tell you where these connections actually are.

The CANBus (in normal use) pulls the DC voltage of around 2.5V either high (for CAN-H) or low (for CAN-L) by a volt or so. An error condition would be that either side of the bus is at 5V or 0V.....

[SilverIris]

The way forward is to slug your way around the TIS as this will tell you where these connections actually are.

The CANBus (in normal use) pulls the DC voltage of around 2.5V either high (for CAN-H) or low (for CAN-L) by a volt or so. An error condition would be that either side of the bus is at 5V or 0V.....

As Always Timm, you are the man! Since it has been raining here all day, I've been spending the day in the books to be fully prepared to jump in first thing tomorrow morning. Took the original diagram from NewTIS and gave it an overhaul to make it easier to understand.

Canbus Diagram.png

The only information I couldn't readily locate was X18835 and X18836's location. I know that X1779 is under the passenger front seat carpet and X1746 is quite distinct under the hood, but where are X18835/X18836?

While cleaning things up yesterday around the DMEs, I took a look at the Diagnostic Connector. NewTIS says there is no Canbus wiring in it as seen here: https://www.newtis.info/tisv2/a/en/e...il-lim/YlZKhSf

Meanwhile, this thread says it is on Pin 2 and 3, but both of mine are missing #3: https://www.bimmerforums.com/forum/s...5-OBD-Port-Mod

Seems kinda silly that BMW wouldn't put in a Test Point for such a complicated system. What do you think Timm?

[Timm]

It is the same plan as with all the other busses - the data is parsed by the IKE and made available on the diagnostic bus, otherwise you would end up with a lot of connections on the diagnostic connector!

CANBus waveforms here:

https://www.meeknet.co.uk/E64/Advanc...is.pdf#page=82

[SilverIris]

It is the same plan as with all the other busses - the data is parsed by the IKE and made available on the diagnostic bus, otherwise you would end up with a lot of connections on the diagnostic connector!

CANBus waveforms here:

https://www.meeknet.co.uk/E64/Advanc...is.pdf#page=82

Sharp as always. Since this thread is touching on quite a few issues that new owners are likely to encounter and be endlessly confused by, it might be a good addition to the Common Issues section.

So I was looking through the log again and came across something interesting.
IKE -> F0/C4 - CAN-bus off
F4/84 - No CAN message
FB/84 - No CAN message (EGS1)
F5/84 - No CAN message (ASC1)
F9/84 - No CAN message (DMEL4)

Combine it with the following link: https://www.ma-bmw.com/forum/viewtopic.php?t=35149
(forum is in French, so Google Translate to the rescue)

F0 CAN-Bus off
F4 CAN Identification missing
F5 CAN Identification missing (ASC)
F6 CAN Identification missing (DME)
F7 CAN Identification missing (DME)
F8 CAN Identification missing (DME)
F9 CAN Identification missing (DME)
FA CAN Identification missing (EML)
FB CAN Identification missing (EGS)
FC CAN Identification missing
FD CAN Identification missing

In fault codes, is it that the first two digits identify the device/system while the second pair classify the fault? The second part is easy enough to find, but I can't seem to find a complete list of the first part.

[SilverIris]

With a shaved-down paperclip, I tapped into the Canbus system and did some testing and here's what happened. All readings were taken at the ABS/DSC Module with it unplugged (Minus One Module for clarity).

CAN-H wire, Pin 24 (yellow/black)
9.7v, measured at ABS (minus 1 module)
9.85v with EGS unplugged (minus 2 modules)
increases by ~0.1-0.15v for each additional module unplugged from Canbus

CAN-L, Pin 40 (Yellow/Brown)
10.26v measured at ABS (minus 1 module)
10.35v with EGS unplugged (minus 2 modules)
increases by ~0.1v for each additional module unplugged from Canbus

I've not ventured inside the car yet to disconnect the IKE (Cluster), LEW (Steering Angle sensor) or EKAT (Electric Cat Controller), but this behavior has been consistent so far. What do you think Timm?

[Timm]

Miles out - something is pulling the CANBus lines high - you just need to find it now! The rest voltage should be 2.5V:

https://www.meeknet.co.uk/E64/Advanc...is.pdf#page=82

[SilverIris]

Miles out - something is pulling the CANBus lines high - you just need to find it now! The rest voltage should be 2.5V:

https://www.meeknet.co.uk/E64/Advanc...is.pdf#page=82

Had a brainstorm over dinner an hour ago. Checking over the log file, every module except one was getting a timeout error.

LEW, Steering Angle Sensor. That got the wheels turning about HOW it measures angle...

Popped on here and started reading:
https://www.bimmerforums.com/forum/s...g-angle-sensor

One potentiometer for angle, one potentiometer for steering wheel acceleration. Jumped over to NewTIS and...
https://www.newtis.info/tisv2/a/en/e...supply/c2XuqPv

That sure looks like a Voltage Divider to PWM frequency converter with a 2.5v float point. A 90s GM Knock Control Module works on the same idea, just backwards. They work by pulsing a ground on the signal input pin (from the knock sensor) which triggers the output pin voltage to drop when compared to the VSS (voltage supply). More ground pulses (aka more knocking) means a bigger voltage difference. On my 20B RX-7, I used 5v for supply voltage and a voltage divider resistor array so it saw exactly 2.5v. Fed the signal into the ignition timing circuit, so it pulled timing back whenever it saw less than 2.5v. Worked like a charm.

Ran out to the car with my laptop, booted up PA Soft and read the LEW. Turning the steering wheel produced wildly erratic angle readings in the Absolute Angle field, with the other 3 fields being rather 'twitchy' at rest. Absolute Angle would ramp down smoothly, then suddenly spike up to 200+.Of the 3 different ways the Canbus section of the LEW can interpret the data (left to right increasing, right to left increasing, distance from center), it fits none of their behavior.

In most potentiometers, it's a carbon track that gives the increase in resistance. wiring it backwards (dead short) alters the width of the track, altering its resistance. Plus, what is currently in the car came from #DD73905 as well, making me suspicious as to if this has happened before. Wouldn't be too surprising.

Soon as there's daylight again, I'm taking apart the dashboard and unplugging the LEW. If my logic is correct, the Canbus will straighten up.