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E46 M3 (2001-2006)

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Old 12-29-2010, 06:17 AM
pcgem1 pcgem1 is offline
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Location: Cary, NC
Join Date: Oct 2010
Posts: 5
Mein Auto: 2004 M3 Convertible
SMG won't shift (solved)

I ran into the problem where my SMG transmission would not shift. I know there are many threads on this topic but what I found was that it took me a few hours of sifting through them to find enough info to do something about my issue other than becoming a 'favorite payer' to the dealer. The many threads I read always left out part of what I needed.

Having said all that, I'm posting everything I learned here in one post....which by the way saved me thousands of dollars so I hope this post will help you too. I'm also including pics of what I'm talking about so you can confidently find the items I discuss on your car.


As the weather got cold, I noticed my SMG transmission wasn't shifting into neutral as easily which prevented the car from starting until after several attempts. Then one day after coming out of work, I couldn't get it to shift at all and had to leave the car in the parking lot overnight. The posts I read where people took their car to the dealer to get this problem fixed said in all cases, the dealer replaced the SMG relay and the hydraulic pump/pressure accumulator (yeah, check out the really scary price here: item #1 Seriously, my family would have gone without Christmas this year if I had to pay for this.

My 2004 M3 only has 40K miles on it so I seriously doubted the hydraulics would be having issues. The faint noise you're supposed to hear (sounds like a small electric motor running from under the car) when you unlock the car or open the door is the pressure accumulator building pressure in the hydraulic system so it can operate the SMG transmission, put it into neutral so you can start the car. Sometimes I heard this, sometimes I didn't hear it at all....which is definitely a problem. I found that when relay switches start going bad, they can really be affected by cold temperatures so I decided to start by replacing the relay and to great relief found that was the problem. I picked up the relay at Carquest for $8.20 including tax and it is virtually the same part. Typically I go to great lengths to get authentic parts but in this case, it really was the same. It took me all of 4 minutes to change it in the parking lot too. If you are having SMG issues, I highly recommend changing this out just to see if it's the problem because it's only an $8 risk but could save tons of money....even if you are not good at working on cars, this is really easy and here is what you need to know.

SMG relay, part number: 12631742690
Typically between $7-$9
You can get it at most autoparts stores, online, dealer, etc.
The first attached picture to this post is a pic of the one I installed

Here is a link for closeup pic and purchase info:

Where this is located in the car: In the engine compartment right in front of the driver in the fuse box/wiring hub. The second attached picture is the location with the cover on.

Using a 1/4" star head screw driver (also known as Hexalobular), remove the 4 screws holding the cover, pull the cover off and you'll see what is shown in the third attached picture. (be careful not to drop the screws...this is easy to do)

The "Salmon" color Red relay is the device of interest. To remove it, you can try wiggling it from side to side while pulling up. Be sure to take note of the small tabs on the side, you may need to gently pry back the plastic pieces holding them to free the relay. I used a small flathead screwdriver to pry up on the relay because my hands were too cold to really get a grip on it. It popped right off, there are no screws holding the relay in place.
Since this was the first time I had seen this relay, I was careful to note the pin layout so I was sure to put the new one in the same way. Usually though, these only fit one way so there is no way to make a mistake when putting the new one in.

Once you've pushed the new one in place and screwed the cover back on, see if the shifting issue went away. I had two alarm lights on my dash still on. The lamp that looks like a gear was yellow and my check engine light was on (or was it service engine??....can't remember). I didn't have time to look up the procedure for resetting these lamps so I figured I would get to it the next day or two. The next day, the gear shaped lamp went out by itself and about 3 days later the check engine lamp went out. I have not had any dash alarms light up since and the car has performed/shifted with no issues what-so-ever.
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Last edited by pcgem1; 12-29-2010 at 06:37 AM.
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