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2008 M5, 155K, Transmission Red Cog (Seasonal Allergies?)

879 Views 17 Replies 5 Participants Last post by  sunilshivaram
I got the transmission red cog, and this message on the dash. Car was sitting all day and I started it and moved it around. Then the red cog showed up. The car was in D3, and it wouldn't "display" anything else. I could move it to "3" and back to "D3". A "+" or "-" on the transmission lever or the paddles wouldn't change a thing. I could move the car to Reverse and the car would go back, yet the display stayed in D3. When i moved it to Neutral, it still stayed in D3.
For moving forward, when i gave it some gas, the RPMs would go up and the car would move forward very slowly.
I brought the car back home, was just around the block, and parked it, and went running with our doggie for an hour.

I come back and start the car, everything normal.
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From ISTA, it shows faults that are stored, but not present. After i cleared all the faults, the SMG faults didn't show up.

I have to say this: I have seen this happen before, the red cog showing up, when the season changes and gets colder.
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Discussion Starter · #6 ·
Sounds more like temporary electrical issues, maybe corroded electrical connectors.
Car has been sitting all day in cold and I tested it now, everything clean, no error codes.

I have seen the red cog show up during cold days, and this is the first time i have captured the error codes with ISTA+.
Will keep an eye on this and update.

I am not running any "routines" on the SMG; just not familiar what to expect and want to avoid getting into unknowns. I have seen nothing but trouble here when people thought they should clear adaptations or run bleeding routines and then it stops working completely or hangs or leaves the car in unusable state.
 

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Discussion Starter · #10 ·
Its been 3 cold mornings, and car is running clean. No issues at all. This appears to be some weird seasonal allergy. The red cog comes and goes ; seen it over the last 4+ years on cold mornings, just once per season, and then disappears.
For 4+ years ok !! Its not something that appears to be failing in the near future now.
 

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Discussion Starter · #12 ·
Happened again ! I cold start the car, then start driving, and the red cog lighted up, limiting Drive to just D3. I pull over, take our dog running, and come back in few minutes, and red cog is gone, no more issues. However, ISTA has captured the errors:
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Its unclear why it points to RED DSC ECU as not responding. After multiple deletes of faults, and starting up the car once, the DSC ECU starts responding and all the faults are gone.
 

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Discussion Starter · #14 ·
If stick this fault into the test plan it will guide you to run the clutch valve adaptation after wiring and resistance check to make sure the valve position is calibrated properly.
This is a bit scary to run and operate. With the s85, I will not venture into unknown territory. I have seen complaints here from members when adaptations failed and SMG was stuck in an inoperable state. This is an "unknown" and I won't open this can without knowing how big the worms are.

If the calibrations are off, or adaptations are flaky, I would expect it to trigger the Red Cog all the time.

Why would ISTA+ complain it can't read the DSC ECU and show it in RED color in the Component Tree ? After multiple deletes of the faults, and a crank on the car, it finally turned Green. Any idea why the ECU would be non-responsive? In computer science, it can happen if its stuck or hung in some loop and can't get out. A full power down (battery disconnect) cycle should restart them back to correct operating state.
 

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Discussion Starter · #16 ·
The ignition must be ON during the scan or the DSC is not going to respond.
Copy that!
The start/stop button has 3 positions: Off/On/Ignition. In the On position, every CPU responds except DSC, I just checked it. When we turn it to Ignition, DSC responds.
The scan now shows zero errors, this Cog thing has to be sorted out. Its purely appearing to be some electrical disconnect, or intermittent interference somehow.
 
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