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Discussion Starter #1
Firstly I want to say that I am a huge fan of this site. The e46 BMW is one of my all time favorite cars and I'm on my third such car, but it is my first time owning a M3. It is also my first time with the SMG transmission and lets just say I'm getting used to it.

I've only owned the car for a few days. I bought it from an independent seller at a very low price. I noticed a few times when test driving it (I started and stopped the car a bunch in the test drive) that it didn't always want to start at the first turn of the key. I knew a little about the oddities of starting the SMG (brake pedal fully depressed, make sure it is in neutral, etc.) so I just chalked it up to my inexperience with the car. Well two days into my ownership I went to start it, and no matter how hard I tried it would not start.

I replaced the salmon relay and started to poke at the EWS (I have an AK90+), but I thought to myself I ought to try bump starting it to see what would happen. I wasn't sure that the computers would let me engage first gear without having "started" the car, but they did and much to my pleasure the car started up and the engine ran just fine. Now I drove it a little ways and noticed that gears did not want to engage after having been started this way. Not only that, but the gear indicator in the instrument cluster does not stop flashing. When I pulled up to one red light, I could not get the car to go in gear (it was as if I was standing on the clutch pedal). From the traffic light, I had to give the car a push to get it moving again and shortly afterwards first gear engaged.

From what I am describing above, I think the PLCD sensor is bad, but without having prior SMG experience I am hesitant to just start throwing parts at the problem. Could anyone recommend something that I can check to confirm that it is the PLCD? If there are folks that have experienced similar issues before, what did you find the problem to be? Anything else I should check in addition? Also, what kind of SMG service should I do while I am under the car?

Thanks in advance for any help and advice!
 

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Could be any number of things. The SMG won't engage gears if the hood or trunk or doors are open, or if the brake isn't depressed.

There are three hood switches, one by the drug bin and two in each of the hood pin holes near the kidney grills - that is what I would try looking at first.

Make sure your brake lights work, as they are triggered by the brake switch which also acts like an SMG interlock.
 

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Discussion Starter #3
Thanks for the pointers. The brake lights are coming on, so I think the brake pedal sensor is ok. Is there a easier way to check the hood switches other than using a multimeter?
 

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Thanks for the pointers. The brake lights are coming on, so I think the brake pedal sensor is ok. Is there a easier way to check the hood switches other than using a multimeter?
Honestly I just disabled the two hood pin switches by jumping the two wires together. Multimeter would be the easiest way to test, I don't think you can log those values.

The switch by the drug bin is what controls the dash light, so that one is easy to test. Some have reported that switch going bad and they traped it down or disabled it in the same way.
 

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I don't think hood switches would illuminate the gear/cog light in the instrument cluster, only the gear indicator would flash and system would not engage any gear. Open driver's door, not sure about passenger one, would also cause gear indicator to flash but it would allow you to engage a gear. Not sure about trunk lid though, I'll have to check on that one.

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I don't think hood switches would illuminate the gear/cog light in the instrument cluster, only the gear indicator would flash and system would not engage any gear. Open driver's door, not sure about passenger one, would also cause gear indicator to flash but it would allow you to engage a gear. Not sure about trunk lid though, I'll have to check on that one.

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I didn't see anywhere in the OP mentioning the cog light. Obviously if you get the cog light that means there are codes in the SMG module that will tell you what the problem is.
 

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I didn't see anywhere in the OP mentioning the cog light. Obviously if you get the cog light that means there are codes in the SMG module that will tell you what the problem is.
My bad, you're right. I must've confused it with flashing gear indicator. Long day at work :(

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My bad, you're right. I must've confused it with flashing gear indicator. Long day at work :(

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All good. Happens to the best of us :).

As a fellow SMG owner I am still learning myself.
 

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Sounds like a bad hood, or door switch. If interior lights light up when each door is open I would eliminate that as the cause and focused on hood switch. Even better if you could read codes, that would point you in the right direction.
Let us know what you find

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Bad hood or door switch should not prevent starting the engine, but rather it prevents from shifting gear.
 

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Discussion Starter #12
Thanks for all the useful information! I double checked the hood yesterday and it was not closed all the way. In my frustration I must not have pushed it all the way shut (I normally just drop it and it closes fine). I still could not start it, so I bump started it again and took it for a test drive. It is shifting fine again, so I think that rules out the clutch position sensor.

Seeing as it still won't start, I'm thinking that it might be a dead spot on the starter. I only have a generic scanner to pull codes from the OBD II port, I can do that this afternoon. Should I invest in a BMW specific scanner to get to the root cause of this issue?
 

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Glad to hear you were able to resolve the SMG issue.
I would recommend INPA or ISTA-D as diagnostic tools. They're easy to get and not so easy to set up but there are plenty of instructions on the web on how to do it. Software is free, you just need to purchase a cable. Make sure the cable you get has a switch, otherwise it will not function with older Exx series cars, like your e46.

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Glad to hear you were able to resolve the SMG issue.
I would recommend INPA or ISTA-D as diagnostic tools. They're easy to get and not so easy to set up but there are plenty of instructions on the web on how to do it. Software is free, you just need to purchase a cable. Make sure the cable you get has a switch, otherwise it will not function with older Exx series cars, like your e46.

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+1 for this advice.

When you try to start the car make sure you're in neutral and foot on the brake. Does it back at all? Make a clicking sound?

Make sure the battery is good.
 

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Discussion Starter #15
So the only code that came out of my generic scan tool was P1434 which seems emissions related, and my CEL is not on.

When I try to start the car, the only noises I hear are coming from the SMG system and the clutch. I don't hear the starter solenoid clicking at all, and the starter does not turn. The person I bought the car from recently installed a new battery, and it does indeed look new. Plus I just drove it for over an hour (by bump starting it), so the battery should have a good charge on it.

I'll definitely pick up the diagnostic cable and the software, is there a particular diagnostic cable that is recommended? I found this one on Amazon, but it seems too cheap to be right: Amazon.com: Taotao Inpa Cable with Switch FT232RQ BMW K+D CAN USB Interface Cable Car Ediabas K+ Dcan USB OBD2 OBDii Diagnostic Scanner for BMW: Automotive
 

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So the only code that came out of my generic scan tool was P1434 which seems emissions related, and my CEL is not on.

When I try to start the car, the only noises I hear are coming from the SMG system and the clutch. I don't hear the starter solenoid clicking at all, and the starter does not turn. The person I bought the car from recently installed a new battery, and it does indeed look new. Plus I just drove it for over an hour (by bump starting it), so the battery should have a good charge on it.

I'll definitely pick up the diagnostic cable and the software, is there a particular diagnostic cable that is recommended? I found this one on Amazon, but it seems too cheap to be right: Amazon.com: Taotao Inpa Cable with Switch FT232RQ BMW K+D CAN USB Interface Cable Car Ediabas K+ Dcan USB OBD2 OBDii Diagnostic Scanner for BMW: Automotive
That cable looks correct.

Check that the battery terminals are clean and tight.

Sounds like a starter issue. But getting a real bmw code scanner is a worthwhile investmebt.

Curious, how are you bump starting with SMG? Rolling it in neutral than shifting to first? Never thought the car would allow that. Learn something new every day.
 

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Curious, how are you bump starting with SMG? Rolling it in neutral than shifting to first? Never thought the car would allow that. Learn something new every day.
+1 on that.
I always thought it wouldn't allow it, I guess live and learn


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So the only code that came out of my generic scan tool was P1434 which seems emissions related, and my CEL is not on.

When I try to start the car, the only noises I hear are coming from the SMG system and the clutch. I don't hear the starter solenoid clicking at all, and the starter does not turn. The person I bought the car from recently installed a new battery, and it does indeed look new. Plus I just drove it for over an hour (by bump starting it), so the battery should have a good charge on it.

I'll definitely pick up the diagnostic cable and the software, is there a particular diagnostic cable that is recommended? I found this one on Amazon, but it seems too cheap to be right: Amazon.com: Taotao Inpa Cable with Switch FT232RQ BMW K+D CAN USB Interface Cable Car Ediabas K+ Dcan USB OBD2 OBDii Diagnostic Scanner for BMW: Automotive
I also think it’s a starter issue. If the dashboard lights up but you only hear the SMG/fuel pumps when turning the key, and the battery is fresh/properly connected, the starter is probably dead. Good luck!
 

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Also, make sure you get good power to the starter. I just saw a guy replace his starter on e60 only to find out that the power cable to the starter was oxidating like hell and wasn't providing enough current. Just a thought.

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