4.8iS Doesn't See a DME!

[aureliusmax]

Originally Posted by MBellRacing

P.P.S.
Edit: Figured out how to search for posts. Didn't find anything with "egs signal" in it. Might still be an idiot.

https://xoutpost.com/search.php?do=f...&starteronly=1

[MBellRacing]

Update:


Okay, my electrical engineer dad came over today and we did a bunch of sleuthing. Here's what we did/found:

• We opened up my old DME and measured continuity on all the pins in the most corroded-looking connector. They all are getting good contact.
• We cleaned [the living f**k] out of that connector with plastic-safe contact cleaner and popped each of the little sub-connectors on and off the old DME pins to clean them the best we could.
• The battery was low after sitting, about 12.1V and then 11.9V after turning the key. We used the reliable old Denali to jump first at the battery in the trunk. This resulted in a big voltage drop for some reason. It could just be that we weren't able to get a reliable connection on the battery. However, with the truck battery showing 12.9V, we were only able to see 12.5V at the X5 battery post.
• We jumped from the under-hood battery posts and we were able to get 14V from the Denali and read with the voltmeter at the BMW battery. The assumption is still that the connection on the jumper cables was bad in the trunk, but just recording our notes for posterity.
• We checked every single fuse again with the voltmeter to make sure we weren't seeing any voltage across them. All fuses appear to be good.
• I triple checked that the immobilizer was installed correctly.
• With 14V being pumped in, we tried to start the car again. No start. The DME still doesn't show up on the Foxwell. However, we got a new warning on the dash: "TRANS: FAILSAFE PROG" and "ENGINE FAILSAFE PROG".
• Went into the Foxwell and saw that there was a new extra code in the transfer case module stating that it had enabled limp home mode. I cleared it. Still no start.
• We unplugged the immobilizer and ran another quick scan on the Foxwell. It does the same thing as the DME-- it just doesn't show up. No fault, just no immobilizer module on the list.

So, my BMW is still "doing BMW things" and holding down the concrete in my driveway. This thing is making me crazy. Any ideas? Our next logical step is to clean out ALL the connectors and check them all for continuity, one wire at a time.

If that doesn't work, I'm going to try and send my DME, my VVT, my immobilizer, and my key back to ECU Pro and see if they can just confirm it all still starts their test vehicle.

If THAT still isn't fruitful, I guess I need to start looking at a professional shop to really deep-dive into this wiring issue, assuming that's what it is. Seriously, anybody want this thing?? Kidding... but not really kidding.

Missing carburetors and points...

[EODguy]

"The battery was low after sitting, about 12.1V and then 11.9V after turning the key. We used the reliable old Denali to jump first at the battery in the trunk. This resulted in a big voltage drop for some reason"

‐‐-‐--------‐----------------------------------------------------
How is your BST?

Your symptoms (some of them) sure sound like a partially functioned BST.

I would also clear the codes and (if BST good) unplug the battery and ground the cables together then reattach the battery (fully charged) and go from there.

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[MBellRacing]

My goodness...



Don't daily drive a Naughties BMW. Big Money Waster, indeed.



The car still won't crank, despite us now having spent another 5-6 hours trying everything we can think of to figure out why the DME is not communicating with the rest of the car. New news:

• I sent back my DME, VVT, EWS, and key back to ECU Pro and they confirmed that all the modules worked together on their test vehicle with zero errors.
• The battery had drooped again to 10.5V after 2 weeks of sitting with the key 598 miles away. Charged it up with a big 2-60A charger we used to use on race cars. Charged it at 2A for an hour and then 20A to get to 12.9V. During the charging process, we disconnected the car's battery terminals and touched them together to "clear the modules" or whatever witchcraft the forums have told me occurs.
• We took the case off the old DME so that we could access the pins at their board connections. We then went through the entire DME to measure resistance across the junctions between the car's wiring and the DME PCB to make sure corrosion wasn't the issue. All pins measured between 0.4Ω-0.7Ω.
• With the case off, we made sure the DME was seeing 12V on the board, which it seemed to.
• The car's OBC now randomly shows the tachometer at 5000rpm, the coolant temperature maxed out, and the oil temperature maxed out. It still says the transmission is in fault mode and that DSC and 4x4 are inop.
• The airbag light is NOT on, so unlikely a BST via the SRS system (I hope).
• Quick scan of the modules now shows 4-5 new errors through the KOMBI, all related to DME communication over CAN.

The only remaining thing I can think to do is to tow the car to a local BMW expert and hope they've seen something similar and know where to snoop. If they can't find anything, I'm literally debating trailering the car all the way up to PA and have ECU Pro look at it, themselves. They mentioned they had a car that took a similar sh*t before. However, it turned out to be a corroded contact issue, and we have sussed that out.



How do I confirm the function of the BST? I do still have three faults in the seat occupancy section of the scanner: an "SBBF Undervoltage" and two "SBBF Control-Unit Fault". Could this SOMEHOW be the issue? My dad and I figured it would be very obvious that the charge had popped and would remove all voltage to the DME. Is this not how it works? Is there like a "code" sent that just shuts down some of the communication to the rest of the modules while keeping the power pins at 12V?



Please, someone help me with this thing. This car is (well... was) my daily driver. This is the second BMW I've owned that has bricked with some mystery DME issue (the first being an E34 540i 6-speed that was turned in on Cash for Clunkers). This is, absolutely, the last Nazirocket I buy. It has ruined me on German cars. It is unbelievably good when it works... but ya know...

[EODguy]

Here's a video on the BST and it can be bypassed.

https://youtu.be/c26Jq1O1m0M

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