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02motive

Cruise Control not engaging (E46 in general)

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Hello all, sorry if I missed to introduce myself to the forums, haven't really found a place to do so. 

As for the issue, there are two parts. 

The first part was when I initially got the car. I noticed that whenever I had a passenger in the car, the CC just wouldn't engage. The indicator would light up for a brief moment and go off. When I was alone, it would engage on first try no issue. I assume that the passenger occupancy mat is shot, since the small black box under the seat is missing. 

The second part is right now. I had to take out my seat out and had to move the car without it. Of course, this set a fault in the Air Bag module that needs to be reset. I've also noticed that I can't engage CC at all. It has the same behavior as when I'm with a passenger. 

Could it be that it's some kind of safety feature from BMW's legal side (air bag fault = CC not working = not their fault if something happens)? I would suspect wiring if I hadn't ended up with the same behavior for my seat, but now I'm not sure. I haven't found anything odd in the wiring, nor that it's been tampered with. 

Thanks for any suggestions/ideas 

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Check your MAF. A faulty one or one on its last legs will cause CC issues. Sometimes people forget to reconnect the MAF when they've been working in the engine bay.
The passenger occupancy sensor has no bearing on whether the CC engages/disengages.

 

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It's connected properly. Is there any way I can check it without diagnostic tools(still have to get one)? I know that the M50/52 from the E36/E34 would change the way the engine behaves when you unplug it (dumps more fuel in).

It's interesting to me that the CC issues got worse after getting the airbag light for my seat, which is why I connected the issue with the airbags

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E46s have a known issue with the passenger occupancy sensor throwing up the airbag light. Not heard anyone else mention CC issues when they get that error. Just fit a bypass kit and away you go (with that issue).

...So it's not linked! BUT if someone has been messing with the wiring on your car before you got it, who knows? I've seen worse!

I'd get diagnostics on it first and foremost and then go from there..

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Is the CC factory fit or has someone retrofitted it? Plenty of idiots out there that have no idea what they're doing. :P

There's no sure-fire way of testing the MAF. Usually you'll have drivability issues like loss in power, hesitation, bad fuel economy etc. If you know someone with an E46 you can swap but ideally you need a scanner/software.

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2 hours ago, Schumacher said:

Is the CC factory fit or has someone retrofitted it? Plenty of idiots out there that have no idea what they're doing. :P

There's no sure-fire way of testing the MAF. Usually you'll have drivability issues like loss in power, hesitation, bad fuel economy etc. If you know someone with an E46 you can swap but ideally you need a scanner/software.

Factory fit. No loss in power, pulls nice, no heasitation etc. Avg consumption is ~8l/100km (~10 when pushing it, ~6 open road and ~8 in the city). 

 

2 hours ago, E46Driver330Ci said:

Yes, there is a way to check without diagnostic tools. Just keep buying parts until money gone. Then inspiration will strike.

Ha ha. Not funny. 

 

3 hours ago, momo said:

E46s have a known issue with the passenger occupancy sensor throwing up the airbag light. Not heard anyone else mention CC issues when they get that error. Just fit a bypass kit and away you go (with that issue).

...So it's not linked! BUT if someone has been messing with the wiring on your car before you got it, who knows? I've seen worse!

I'd get diagnostics on it first and foremost and then go from there..

I've read that. Easy to break as well.. The bypass kit is the plan, since I don't fancy handing out ~100 euro for a new one, just so it breaks in a year. Wiring seems fine, checked under the dash, nothing funny going on under there. I just find it strange that it worked at first when I was alone and not when there was a passenger and now it's not working at all, but I have the airbag light :D Acquiring diagnostics is also in the works, so we'll see once I hook it up

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Do you have a local specialist you could pay to put it on diagnostics in the meantime?

No point throwing money at it unless you know what's going on.

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4 minutes ago, momo said:

Do you have a local specialist you could pay to put it on diagnostics in the meantime?

No point throwing money at it unless you know what's going on.

I could find one, yes

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An update to this - connected the car to INPA, it has a fault for lamda controller (not sure what it is) and the oil level signal seems to be missing. There was also a fault for MF wheel interface, but since it registers all buttons as working, I believe it's related to the condition that CC can't work if there are faults on the ECU present (this claim is taken from WDS)

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Not sure about that claim. My car was running with 8 or 9 faults on the ECU and the cruise control always worked. The only time it exhibited issues like you're describing was when I had a sticky button on the MF wheel.

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11 hours ago, dontpannic said:

Not sure about that claim. My car was running with 8 or 9 faults on the ECU and the cruise control always worked. The only time it exhibited issues like you're describing was when I had a sticky button on the MF wheel.

What do you mean a "sticky button"? I toggled them with while monitoring INPA and they seemed to work fine. Either way, I will certainly need to investigate some more 

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No faults for either of those at the moment. I assume that there would be a fault stored in the system if either of those was faulty. A bit busy with something else, so I'll play with it later

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On 12/09/2020 at 09:53, 02motive said:

 

What do you mean a "sticky button"? I toggled them with while monitoring INPA and they seemed to work fine. Either way, I will certainly need to investigate some more 

What do you think I mean? A sticky button is a button that's sticky - gets stuck down, or doesn't engage properly. Isn't as smooth as a normal button, just a bit sticky.

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Issue solved - it was the clutch switch. INPA showed it as working, but it seems it wasn't as it should. Took it out, cleaned it as it was dirty, plugged it back in and toggled it on / off with a small magnet. Now CC works without issues. 

image.gif

Edited by 02motive

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