SMG Problems

[beyondm3]

My '02 M3 SMG (125k mi) started having problems recently. When the car is cold, it starts up instantly and the SMG works like a charm. No problems, no complaints under any type of load. However, when I shut off the car (when it is hot after being driven) it won't start again. The SMG remains in neutral and the car refuses to start, I can move the gear selector to the "R" and "1" position, but the gear will not be selected. No starting procedures take place.

I pulled the codes using the Peake tool, I got an exhaust temperature sensor code and I believe the SMG Safety Concept code (couldn't find much on this).

Through logic, I thought maybe it was the temp sensor on the transmission, so I replaced that. This did not fix it. I did not think it would be the exhaust code as in my mind, I did not think this would affect the SMG, from brief research it would only make the car run either rich or lean (don't recall the specifics.)

Now that I have typed this out, it makes me begin to think about replacing the gear position sensor but it still boggles the mind a bit seeing how the car runs perfect from a cold start.

I have read several posts regarding SMG issues and I can't quite find one that replicates my issues. I was hoping someone might be able to chime in with a similar experience or perhaps some insight as it would be greatly appreciated.

[dalecan]

I just converted mine to a stick so if you need any SMG parts let me know (they're all still in my garage).

[2002beb]

https://www.e46fanatics.com/threads/...k-here.855810/

[Kevin2772]

Hey Dalecan, did you do the conversion yourself? or did you have a shop do it? Any idea of costs. From all ive seen online, conversion and replacement are about the same.

[dalecan]

Hey Dalecan, did you do the conversion yourself? or did you have a shop do it? Any idea of costs. From all ive seen online, conversion and replacement are about the same.

I did it myself mate. I was putting in a new engine so I did the conversion at the same time.

[eacmen]

Using INPA or similar tool log all the sensor values related to the SMG. Make sure you're maintaining hydraulic pressure. There are many sensors that feed into this system. Without a specific code that's all you can really do to narrow down the issue.

There are switches in the hood pin holes that serve as an interlock, maybe they go bad when hot?

[jonnysideways]

When I had issues with SMG of which o had 4, the salmon coloured relay was fist to switch out. Then check.fulid levels for the chf11 SMG fluid. Check in inpa if you can that the pressure is ok for the SMG pump when warm , as the pressure / oil will be affected when warm. As for conversions I saw Wheeler Dealers do one on TV recently, and I was going to flow Sam procedure on my E36 but I just did what they did but used a manual gear box so you don't need the engineering bits done. The episode was worth a watch.

In all my years of SMG ownership only had a gear position sensor and relay fail on the e46 but had total gearbox failure on the 2nd of my e36s.

Hope this might help.