DSC and LWS CAN timeouts no communication errors

[bavmotorwerkz]

Anyone dealt with both DSC and LWS timeout errors?

My 2004 M3 after having put it all back together from an engine rebuild and transmission refresh (including SMG to 6MT conversion via RTD shifter - 420g SMG bellhousing intact - DSSR only, no GPS sensor installed - clutch pedal sensor wired direct to brake light switch using clutch pedal switch PN ending in 700) is constantly upon putting key into position 2 and immediately scanning DME error codes shows:

• DSC CAN timeout
• LWS CAN timeout
• Tempomatsystem Interruption (if this is the ambient air quality/temperature sensor, it's because I have it unplugged currently)

Because both the DSC and LWS CAN timeouts are consistent together, I of course get the trifecta lights on the dash. My speedometer doesn't work, and I'm getting bouncy RPMs that lead to random stalling when coming to a stop pushing both the clutch pedal and brake pedal in (I have to blip the throttle and brake or heel/toe to keep it alive until I'm nearly stopped, or it will stall and have to start it up again).

Some things to note and that I've already attempted but to no avail:

• Ensured clutch pedal switch is ending in PN 700 instead of the generic switch used by non-Ms.
• Ensured the clutch pedal switch wiring to the DME is set to the 2nd to last cabling coupler/connector from the right, instead of the 2nd to last on the left as seen on SMG to Manual conversion tutorial video on youtube.
• Already replaced fuel pump with Deatschwerks DW200, new fuel pressure regulator, new fuel pump regulating module, and got injectors rebuilt/cleaned/tested by Race German.
• Replaced ICV, TPSs (both), camshaft position sensors (both), crankshaft position sensor, using OE clamps on intake manifold, cleaned MAF sensor, ensured no vacuum leaks, even to the AFE Stage 2 intake installed.
• Unplugged currently installed steering angle sensor with brand new sensor, still get LWS CAN timeout error.
• Cleaned/reseated rear left wheel speed sensor, still get DSC CAN timeout error. I have a new sensor waiting to get swapped in, but highly doubt this will help since its a timeout/communication error.
• Replaced car battery with brand new Interstate battery; when engine is off, battery voltage reads ~12.x V (can't remember the decimal amount), when running I think it reads at 14V? It's a new battery, and as part of the engine rebuild I replaced the original alternator and starter with new Valeo replacements (not rebuilt/refurb'd - brand new).

When I use ISTA+ to follow the diagnostics graph of the chain for the LWS and DSC modules, they show that they can't be communicated with/to. I'm able to communicate to the EWS module without any issues, no error codes when scanned.

There might be some things contributing to the random RPM bounces to stalling when coming to a stop:

• I can tell that the center support bearing for the driveshaft is shot, needs replaced, lots of vibration and rattling coming from the driveshaft area.
• Also, I noticed some VANOS control errors for both intake and exhaust and cyl misfires, but I think the misfires were from using bad gas (just filled it up with 93 octane, gone thru 1/4 tank now and I think the misfires have stopped), the VANOS control errors I thought were timing related, but when I pulled the valve cover and checked timing, the cams were set pretty much perfectly. I've already previously done a VANOS unit rebuild using Beisan Systems shortly before I pulled the engine to rebuild the top and bottom ends with aftermarket parts, along with machine shop work, so it's using the modded oil pump disc, has new piston seals, new VANOS hub washers/plates, rebuilt both intake/exhaust splined shafts with new washers to remove axial play, has a rebuilt/refurb'd solenoid pack. I noticed a bit of oil residue on the solenoid pack wiring harness connector, so I cleaned it up a bit and seems to maybe have resolved the VANOS control errors (we will see over time).
• I'm using DKM Stage 2 clutch kit - the flywheel is a steel flywheel, lighter than the dual mass OE FW, but heavier than an aluminum FW. I've raised the idle RPM to 900 from stock level using ECUWorx, but does not resolve RPM drop/bounce and stall when coming to stop.

I've unplugged random things to see if I can get CAN bus communication to resume to the DSC and LWS modules, such as unplugging the brake light switch itself, the OE installed steering angle sensor and plugging in the new one, I even saw a video on youtube (might be taken down now) of a guy who unplugged the xenon headlights which resumed CAN bus communication on an e46 M3, but to no avail. I also do not have the TCM plugged in since converting to 6SM via RTD shifter; I used ECUWorx to configure DME to manual instead of SMG, and coded out the requirement to start the car up with the clutch pedal pressed in via NCS Dummy / Expert.

I have yet to check the fuses for the DSC module, etc. will be doing that soon. I also have a Mishimoto electric fan shroud w/ NPT sensor wired up with its own module and fuse assembly to the glovebox area (can't remember which fuse the instructions told to piggyback off if you will); I disconnected the power cables (both positive and negative) from the quick access connectors in the passenger drug well bin area to essentially disconnect the electric fan to see if it was causing electrical problems, but didn't seem to improve anything.

Hoping someone has also encountered a CAN bus timeout communication problem with both the DSC and LWS modules for e46 M3.. and can provide their input on troubleshooting/fix. Thanks so much for your help, so bizarre!!

[sapote]

"I thought were timing related, but when I pulled the valve cover and checked timing, the cams were set pretty much perfectly."
Cams were set perfectly relative to what? How do you know that the vanos pistons are at their most forward position during timing check?

"Ensured the clutch pedal switch wiring to the DME is set to the 2nd to last cabling coupler/connector from the right, instead of the 2nd to last on the left as seen on SMG to Manual conversion tutorial video on youtube."
This can be related to the engine stalled at stop. Did you verify the clutch switch close/open status by using INPA or other tool?

The dash cluster display also communicates via CAN bus; do you have correct information displays on the gauges, such as coolant temperature?

[Arith2]

Check the physical layer first. Check all relevant fuses. Your ISTA should have wiring diagrams. Are the connectors and relevant wire ok? Is there power? What do the grounds look like? What wires do they share? What module talks to them both? I believe they both go straight to the instrument cluster, which is also you're gateway. I would focus in on the CAN issue first as there is a possibility it may solve the dipping. It's not a guarantee but it could be affecting other CAN signals.

[bavmotorwerkz]

"I thought were timing related, but when I pulled the valve cover and checked timing, the cams were set pretty much perfectly."
Cams were set perfectly relative to what? How do you know that the vanos pistons are at their most forward position during timing check?

"Ensured the clutch pedal switch wiring to the DME is set to the 2nd to last cabling coupler/connector from the right, instead of the 2nd to last on the left as seen on SMG to Manual conversion tutorial video on youtube."
This can be related to the engine stalled at stop. Did you verify the clutch switch close/open status by using INPA or other tool?

The dash cluster display also communicates via CAN bus; do you have correct information displays on the gauges, such as coolant temperature?

Thanks for these questions. Sorry to be brief, but for cams timing I use the Schwaben tool. For the pistons, I ensured they were in their most forward position upon the VANOS unit being installed/re-mated to the cylinder head from the rebuild project. The VANOS related errors themselves seem to relate with the solenoid pack, which, given it's had not much mileage put on it yet as a Beisan rebuilt unit, something leads me to believe it's due to electrical problems (see further down on this post).

The dash cluster does show correct information on the gauges, such as oil and coolant temps, along with RPMs from the crankshaft sensor. It displays other indicators that are correct, such as the trifecta due to DSC and LWS modules not communicating to DME. Only the speedometer doesn't work, which seems to be related to the same chain of connectivity for the ABS, DSC, and LWS.

I've definitely verified with the 700 clutch switch that the sensor is reporting to the DME correctly concerning the open/close status indication.

To add as an update in overall troubleshooting, I finally got BMW scanner 1.4.0 working in Win11, and has reported errors that relate to electrical problems, such as Battery Voltage Open Circuit in shadow memory for the ZKE, and Power Supply Undervoltage for the SRS.

I plan on measuring the overall draw from a potential parasitic power drain with the car off and asleep, then will start to measure the drop in the power drain draw from pulling various fuses (to also perform visual inspections) to try to isolate.

I'll gather & post up some screenshots soon of things I've seen in various software diagnostics tools, such as the flow chart leading to the DSC and LWS in ISTA+, along with the various errors found in BMW scanner after clearing codes, then rescanning.

[sapote]

To add as an update in overall troubleshooting, I finally got BMW scanner 1.4.0 working in Win11, and has reported errors that relate to electrical problems, such as Battery Voltage Open Circuit in shadow memory for the ZKE, and Power Supply Undervoltage for the SRS..

I believe the DME has 2 CANbuses: the one going to the dash cluster is working, but the 2nd to the SMG having issue. This might be related to the SMG conversion.
The error about batt voltage open circuit might also be related to bad CANbus communication to cause reporting junk data, and so junk errors. Maybe.