Trans starts out in M mode on it's own

[bigvettefreak]

I bought a 740iL non sport with the A & M switch to change the trans mode.

When I first drove it for a short test drive, it had a yellow M showing in the shift indicator area and wanted to start out in manual mode (3rd or 4th gear). I pulled it into 2 and it started out fine, then after driving a 1/4 mile or so, the M went out and the trans acted normally.

Trans never made any funny noise or slipped etc, just tried to stay in manual mode on start up then begain to work in Auto mode after being driven for a short distance.

After I bought it, when I first started the car and pulled away, it did the same thing only this time it went into auto mode faster. I drove it for about 40 Plus miles (on an interstate & it drove great!) and after I got home, I stopped for gas. When I started the car up to take it to my mechanic, it did not show the the yellow M and shifted into first gear correctly.

It has still not shown the M when first started and a week has gone buy.

Any ideas?

I am going to have a pan fluid & filter change done, plus clean the A-M switch and see what happens.

Maybe from sitting for the couple of months that it wasn't driven, it caused the computer to get confused or a selonoid to stick?

Look forward to getting your ideas.

[tommyb2b]

Before doing the fluid change just clean the switch! Im 90% sure its your A/M switch!

[bigvettefreak]

The A-M switch seems free, easy to move. The cup holder is clean, no spills of any kind and it is free too, so I don't think anything was spilled in that area that would cause a sticky switch.

I did push the switch to A the first time it happened and it did not change anything. The trans did start to shift as it should after being driven for about a 1/4 mile.

The other reason I am reluctant to call the switch, the trans started working as it should after being driven less than a 1/4 mile without touching the switch the second time I drove the car.

Then after driving the 40 miles, it was working fine, no yellow M at start up.

Strange.

[Se73n]

These car's get some weird gremlins. Just have a AAA membership and shrug it off.

[martyanderson10]

I would still bet on the switch being faulty. Another thing worth trying is to do a battery reset. Disconnect the battery and wait 20 minutes then hold the two terminals together for 20 seconds and reattach to battery.

[nah2323]

BVF, all of the issues you're having seem to point to electrical issues. Either ignition switch or the alternator is slowly dying. As either/both of them get wors,e more issues will arise!!

You've had:
Radio - no sound
Trans - Manual mode at startup
ABS DSC lights

Someone else care to comment on that?

[IcemanBHE]

Nope...Id be doing the old voltage test. See DIY forum.

[bigvettefreak]

I'll Have the battery & charging system checked pronto!!

What kind of a voltage drop would cause these problems?

[Showtime22]

The sunroof switch on headliner will swap right in to the A M switch on the console. You can swap the sunroof switch down to test.

Not sure but - I think if you shut down the car in M mode and you restart it and the M is still on the dash lit up then the switch is holding it in M mode and bad.

[bigvettefreak]

Well the Battery is good and there are not charging issues.

The Auto Manual switch is also good , so why would the yellow M come on at start (not all the time) and go off on it's own. (I have had it go on after I have been driving and then it will go off too)

What causes the trans to shift modes? a control Mod.? Servos in the trans?

The trans shifts smooth etc. other than the pesky wanting to be in the Manual mode when it wants to.

Is there a way to disconnect this feature? If I wanted to shift gears, I sure as heck would not have bought a 740iL.

[IcemanBHE]

Leave the A/M plug unplugged. See if it still does it.

[martyanderson10]

Well the Battery is good and there are not charging issues.

The Auto Manual switch is also good , so why would the yellow M come on at start (not all the time) and go off on it's own. (I have had it go on after I have been driving and then it will go off too)

What causes the trans to shift modes? a control Mod.? Servos in the trans?

The trans shifts smooth etc. other than the pesky wanting to be in the Manual mode when it wants to.

Is there a way to disconnect this feature? If I wanted to shift gears, I sure as heck would not have bought a 740iL.
How did you determine that the switch is not bad? I had the EXACT same problem and put in another switch and it has not done it since then (over two months ago). Not saying your wrong, just curious.

[bigvettefreak]

Mechanic tested the switch and told me it was working as it should.

[Qsilver7]

...
I did push the switch to A the first time it happened and it did not change anything. The trans did start to shift as it should after being driven for about a 1/4 mile...


...why would the yellow M come on at start (not all the time) and go off on it's own. (I have had it go on after I have been driving and then it will go off too)

What causes the trans to shift modes? a control Mod.? Servos in the trans?...


Mechanic tested the switch and told me it was working as it should.

Something is not quite right...from the first two quotes...it's obvious that what the "mechanic told you"...isn't correct.

Just because the switch "looks" good from the outside, doens't mean that there isn't residue from a previous spill gumming up the insides of the switch UNLESS you remove and disassemble it.

And as mentioned by Marty.... if you don't feel inclined to open the switch to see what may be inside it...you can pull the sunroof switch out and swap it in. Then move the switch fore/aft and you should be able to see the tranny mode change from A (adaptive) to M (manual)...and you should be able to select this at will plus it should stay in the mode you select.

You've looked at a lot of potential culprits but you keep dismissing one simple step that will totally exonerate the tranny switch...open it up and see if there is residue from a previous spill. Again, the switch would have been cleaned up and the button manipulated enough that it moves...but the contacts inside the switch could still have residue that is preventing the switch from working properly.


http://www.nmia.com/~dgnrg/console6c.jpg

[bigvettefreak]

Problem solved. It was not the switch but a Wire in the harness. Mechanic traced the wires and found a problem. Seems there was an auto start installed at some time and someone had been poking around the several harnesses trying to find what ever it was they needed and caused the problem that took a while to surface.

No more yellow M :redspot

Thanks guys, I have learned alot and if this pops up again, I,m good for the anwer.

[bigvettefreak]

OPPS!!!! spoke too soon. http://images.bimmerforums.com/vb3images/icons/icon9.gif

With the harness checked and given the all clear, I thought I was good to go.

I decided not to plug the harness back into the switch as I have no intention of ever using that feature and can plug it in if I sell the car and why tempt the Gods, the light was off and it was shifting properly unplugged.

WRONG! The stupid yellow M came on today and the car went into manual mode again only to go out of manual mode when the car was restarted. :mad

Now what??? :eyecrazy This seems to be an intermitten problem leading me to think it may be a trans control mod or a switch inside the trans that is goofy.

Anyone have an idea? :help Is there a code that I could or should look for?