teamsmith

Hello everyone, I am running into a dead end with some error codes. Here's my whole story:
2006 530xiT Auto with regular diamond key (no start button) 70,000 miles.
Previous transmission related service (March, 2012) 48,000 miles: Mechatronic sealing sleeve replaced, new transmission oil and filter. service advisor said if leak continued I'd need a new pan. No current external leaks noted since by myself or my mechanics.

Starting about 4 months ago: I've had the following issues, in the best chronological order as I can remember:
-Right reverse light intermittently out. I replaced the bulb, I got the error a couple more times but now works fines.
-Keyless remote stopped working. I had left my key (diamond key) sitting in the idrive console overnight. the next morning it stopped working. I tried the other key, neither worked. My FM appears to be working fine (although I really only listen to Sirius)
-One day noted my clock was 00:00:00 and had to set it. This made me think I have a battery problem, although it started fine.
-My car had went into transmission limp mode 4-5 times in a 2 month period, but would come out of it if I pulled over and restarted. no harsh down/upshifts were noted.
-Car battery dead, won't start. Jumped off and driven to Autozone. They test the battery as 'good' but needing charge and test the alternator as 'failed diode test.' I proceed to take the car to an independent BMW mechanic. They tell me the battery is dead but the alternator tests fine. the battery was less than 2 years old so they (Interstate) replaced it under warranty. It's a non-AGM regular battery. At the time, I told them about the transmission limp mode and they said it was likely just the dead battery.
-Limp mode returned about a week later, twice in one day. Seems to happen when I'm descending either down a mountain or down an offramp and it downshifts a little harshly.
-PDC failure. I had replaced the right middle front sensor a couple months ago and was able to diagnose with the 'listen for the ticking' trick. Now there is no ticking anywhere but the little screen of my cartoon car still comes up on the iDrive and pdc light flashes.
-left license plate light bulb out message, but only sometimes. I'm guessing there is a short in the tailgate wire harness.

Initial diagnosis:
-Keyless remote: I removed the rear spoiler and looked at the diversity amp module. It's dry and clean as a whistle, no signs of corrosion or moisture. Could the short in the tailgate harness (intermittent license plate light out) be causing the problem with the diversity amp)?
-PDC: I pulled the spare up in the boot and found no signs of moisture in the module foam area.
-Transmission: Replaced the ABS relay in the boot per recommendations from a UK forum member who seemed to think it was related to the charging
-Electrical: Bought a cheap volt meter that plugs into cigarette lighter. Voltage will drop slightly to ~13 while driving, but mostly stays around 14.1. After 12-14 hours of no driving, battery charge is still at about 12.2-12.5. During the last two limp mode encounters, no voltage drop was observed.

3 weeks following the last limp mode (and secretly hoping the problem was fixed) limp mode returned and this time with the SES light. Back to the independent shop with the following codes returning:
-4F8D Ratio Monitoring, gearshift 5-4
frequency: 2 (last time ~80 miles ago)
-2AD0 No message from transmission control unit, receiver DME, transmitter EGS/HIM/SMG/DKG
Frequency: 7 (last time ~10 miles ago). Interestingly, per autologic, the last two faults were recorded in gear '0', with 'engine off', and 'engine at standstill'. The first fault was recorded in gear 5 at idle speed, although I'm not sure how I can be at idle speed in gear 5.
-2A98 Crankshaft - inlet camshaft, reference
Freqency: 1 (~120 miles ago)
-A0B5 Fault, road speed signal
Frequency: 1 (~600 miles ago)

The PDC came back with a
9E32, front centre right (the one I replaced)
9E3A, wire, front centre right
9E3B, supply, ultrasonic sensors.

I assume the first two PDC codes are legacy from before I replaced the sensor, unless my new sensor is bad.

My indy said that, based on the fact so many modules are not communicating (TCM, PDC, Diversity Amplifier), he thinks it might be a problem with the CAS, which they are unable to access as an independent. So, I drive it over the to dealership. Unfortunately, the indy inadvertently cleared all of my codes so they couldn't see anything wrong with it. After considering briefly trading the car in before the codes came back, I got the autologic report from the indy and sent it to the dealer. The dealer looked at the codes and charged me $144 to tell me I needed a new transmission. I asked about the indy's theory about the CAS being the problem but the dealer just stonewalled and said I needed a new transmission again.

So that is my story. Aside from having to use my key to unlock the door like a caveman, the car operates perfectly normal.

Oh, one more piece of information; About 6 months ago I did the mod of adding a sport button by tapping three wires into the back of the DSC module to activatee FDC, Dynamic Driving Mode, or Sport Mode (same thing, different names). I'm happy to tear the dash back apart and undo it but the indy didn't think it would have any bearing on my issues; When I told the service manager, he just looked at me like I was speaking Japanese and repeated, more slowly, "you need a new transmission."

From my reading, it seems like the 2AD0, no message from TCM seems to be the major offender. There is a service bulletin out for 4F8D that involves me driving up to 25mph and coming to a stop 10 times which I plan to do shortly.

Thoughts?

Ultimately, I can get my transmission (6HP19) rebuilt at europeantransmissions in Atlanta for ~$4k but I'm not convinced it is needs one, no matter how many times the dealer repeats it or what level of condescending tone he uses.

BimmerFan52

I just skimmed your post quickly and might have missed something, but I would look more closely at the alternator.

I don't know how cheap your cigarette lighter voltmeter is, but you shouldn't be seeing 13V on the system with your battery at less than an 80% charge.

Failure of the voltage regulator on the alternator can be very intermittent. When mine failed, the alternator ramp up was too slow, and with an already low battery charge the ECU and CAS would throw a low system voltage fault and kick out the terminal 30g relay, which provides power to the transmission control module and dynamic stability control modules among other things, lighting up the dash. I would pull over, turn off the engine, restart and it would be fine. But as time progressed and I monitored the cigarette socket voltmeter while driving the fluctuations in voltage were getting worse.

I would suggest you probe the connections under the hood with a multimeter while someone else starts the engine cold. Monitor the alternator ramp up voltage and have the person in the car occasionally call out the voltage they see on the cigarette socket voltmeter to check its accuracy against the multimeter. The first cigarette socket voltmeter I bought was terribly inaccurate but the one I have now is very accurate compared to a digital multimeter.

teamsmith

thanks for the feedback. This is the volt meter I bought:
Amazon.com: INNOVA 3721 Battery and Charging System Monitor: Automotive

When I start the car, it usually shows 11.8+ volts, then within 5-10 seconds is up to 14 volts. It never goes higher than 14.1-14.2 and only dips to low 13 occasionally; it most commonly drops when I come to a stop. Sometimes when I put it in park it drops to 12 or even slightly below 12. I have not had any low voltage messages. The only dash light I have had is the transmission malfunction, and then last weekend when the SES light came on (it's now off). I have had the errant flat tire message but I have never had a flat tire; that may be due to the road speed signal fault. I don't have TPMS, just the dumb one that measures wheel speed.

I would love to install a new VR and have that be the source of the problem. due to the irregularity (and recently replaced battery) my gut tells me that it's something electrical and not mechanical. I don't think I mentioned above but I did get my battery coded. Prior to the new battery, I read the charging voltage as 14.6 on the battery terminals with a multi meter.

jgt

My vote is its something electrical. Really basic but make sure your battery cables are connected tightly. I received an SES, transmission malfunction, and an I-Drive reset from a negative battery cable that was SLIGHTLY loose. It wasn't even loose enough to remove by hand but apparently just enough to cause all sorts of weird error messages. Also you might want to try disconnecting your IBS on the negative battery cable and seeing if that makes a difference since they do tend to short out frequently.

jgt

PS. I also considered my alternator was going out but voltages were similar to yours with no weird spikes after hooking it up to my BT diagnostic tool. Tightening the negative cable fixed my issues.

teamsmith

I just had new error message on the way back from lunch. SOS call system malfunction, which apparently also disables my Bluetooth. I am fantasizing about torching it and collecting the insurance at this point.

teamsmith

I'll check the battery cables but, given I was having the problem before I got a new battery, it's hard to imagine it was loose before and after. I know it had the IBS cable recall done a couple years ago with the new connector and such.

twh

You may have multiple problems all with different root causes or you may have one root cause for most of the problems. I spent most of my working life working as an engineer working on computer hardware and software. This sounds like one of those cases where a lot may be related to one root cause. I'd start by debugging the problem/symptom that is present all the time. Debugging intermittent things is hard. Debugging consistent failures is easier. You may find that if you make the key fob work that everything else is fixed. Even if they are unrelated, and you spend the money for a new transmission, you want a key that works! There is no way I'd replace the transmission in the face of so many issues that may have another root cause.

KyleB

How many times has the 4F8D code been cleared and reappeared? You don't need a new transmission. BMW dealers are trained to replace the complete valve body assembly (Mechatronic) or replace the entire transmission. They are literally not taught to service individual components of the transmission.

4F8D is a ratio monitoring code. The TCM is seeing slippage in that particular clutch pack, and placing the transmission into failsafe mode. The likely cause of your slippage in that pack, and any other pack, is with the valve body (Mechatronic). 9 times out 10 its worn out shift solenoids. If you let it keep slipping like that, then yes you will need a new transmission. Those clutch packs are not made to slip like a standard clutch is. They burn up very quickly if they slip too much and too often.

I was getting repeated 4F85 and 4F81 faults. I would clear them, only to have them come back within two weeks. I replaced all of the shift solenoids, bridge seal, and the four sealing sleeves. That was 3000 miles ago and (knock on wood) I have never had the problem come back.

Best of luck with the car. Another example of shoddy engineering by ZF. These transmissions are a joke.

teamsmith

could there be a bad ground that is robbing power from these other systems? I'm getting intermittent lost signal from the TCM, I've lost the signal from the antenna amp module, the PDC has a power supply fault, I've got a couple symptoms of a short in the tailgate wire harness. Could these shorts be causing the modules to fall out? Should I start by pulling the wiring harness from the hinges in the tailgate? There's just so many issues, I really don't know where to start. And, like the Indy said, it may come down to being a bad CAS and replacing all the modules might not fix anything.