Cruise Control Stopped Working in 5th and 6th Gears Only

R

radicalmachine

Member
Hi Chaps,

Odd one for you. Factory-fitted cruise control on my 2010 E89 has always worked no issues, until now:

Cruise control works absolutely fine above 20mph in gears 1-4, but for no apparent reason not in 5th and 6th gears. If cruise control is engaged in 4th gear and I change to 5th, it disengages with the yellow cruise control warning light (indicating pre-conditions for cruise control are not met). If I try to engage cruise control while in 5th or 6th, I get the three-dashes (---mph) instead of the speed.

Scratching my head on this one, as I'm not getting the cruise control malfunction light, and works no problem in other gears. There are no fault codes in the ECU to indicate any issues.

Anyone seen this before?
 
This is only a wild stab, but is it maybe thinking the revs are too low?
Does it measure that?
I don't know, just saw a straw blowing by and clutched at it.
 
This is very strange. On mine it won't let me do cruise control in sport+ mode but that's it other than below 20mph.
 
radicalmachine said:
Hi Chaps,
Anyone seen this before?
Click to expand...
Are you on stock tyres/wheels?

Just a comment on another forum with a similar issue.. although they had retrofitted cruise and it needed some additional coding...

https://www.bimmerfest.com/forums/archive/index.php/t-935478.html
 
I was thinking it could be down to wheels and tyres too. Having wheels with a larger rolling radius will cause cruise control issues, people often have this problem when changing the final drive ratio on their car, cruise will stop working in higher gears.
 
Thanks for the thoughts chaps.
She sports genuine BMW 19inch V-Spoke 296 wheels with Goodyear Eagle F1 Asymmetrics all-round, so I suspect that's not the issue. I've just taken ISTA-D outside on the laptop to make sure I'm not going mad, and there is a single fault code 'A6A2 Soft Close Automatic' in the CTM module (so clearly an issue for another day :rofl: ).

Taken her out for a spin and sure enough cruise control engages no problem up to 4th, and disengages in 5th / 6th. Nothing has recently changed on the car except a new battery but if anything I would have thought that would nix the entire system not just in 5th and 6th gear.

Proper head scratcher!!
 
Your changing up a gear when you are going to slow, the car recognises this and wont allow you to use cruise as revs are too low. If you go 5 mph or so faster I am sure it'll be fine.
It'll do this on hills as well if the revs are too low.
 
Hmmm it's an odd one. Could your clutch be worn at all (check by putting into top gear, holding the brake lightly and trying to accelerate) if the revs rise with no speed increase yo have a slipping clutch.

Other than that I can only think of a DSC control unit problem :|
 
All good suggestions chaps:

mcbutler said:
Your changing up a gear when you are going to slow, the car recognises this and wont allow you to use cruise as revs are too low. If you go 5 mph or so faster I am sure it'll be fine.
It'll do this on hills as well if the revs are too low.
Click to expand...

Doesn't matter how low or high the revs are or how slow or fast I'm going, cruise control gives me '---mph' when attempting to set while in 5th or 6th, or displays the 'cruise-control pre-conditions not met' symbol when changing up from 4th to 5th.

Nictrix said:
Are you putting it in 6th and then engaging cruise or engaging cruise and then changing gears?
Click to expand...

Both, cruise control gives me '---mph' when attempting to set while in 5th or 6th, or displays the 'cruise-control pre-conditions not met' symbol when changing up from 4th to 5th.

ph001 said:
Hmmm it's an odd one. Could your clutch be worn at all (check by putting into top gear, holding the brake lightly and trying to accelerate) if the revs rise with no speed increase yo have a slipping clutch.

Other than that I can only think of a DSC control unit problem :|
Click to expand...

Tried this just now and no slippage, clutch holds well. :driving:

I thought it could perhaps be related to tyre pressure, so topped the air up to 2.4bar in front and 2.9 bar in rear as recommended on the vehicle, but no dice there either. I guess the last thing I can try is get familiar with NCSExpert and check that cruise-control is coded correctly as per Clarker63's suggestion, though cruise was factory-fitted so I feel this has a slim chance of yeilding results.

Keep 'em coming boys
 
radicalmachine said:
All good suggestions chaps:

mcbutler said:
Your changing up a gear when you are going to slow, the car recognises this and wont allow you to use cruise as revs are too low. If you go 5 mph or so faster I am sure it'll be fine.
It'll do this on hills as well if the revs are too low.
Click to expand...

Doesn't matter how low or high the revs are or how slow or fast I'm going, cruise control gives me '---mph' when attempting to set while in 5th or 6th, or displays the 'cruise-control pre-conditions not met' symbol when changing up from 4th to 5th.

Nictrix said:
Are you putting it in 6th and then engaging cruise or engaging cruise and then changing gears?
Click to expand...

Both, cruise control gives me '---mph' when attempting to set while in 5th or 6th, or displays the 'cruise-control pre-conditions not met' symbol when changing up from 4th to 5th.

ph001 said:
Hmmm it's an odd one. Could your clutch be worn at all (check by putting into top gear, holding the brake lightly and trying to accelerate) if the revs rise with no speed increase yo have a slipping clutch.

Other than that I can only think of a DSC control unit problem :|
Click to expand...

Tried this just now and no slippage, clutch holds well. :driving:

I thought it could perhaps be related to tyre pressure, so topped the air up to 2.4bar in front and 2.9 bar in rear as recommended on the vehicle, but no dice there either. I guess the last thing I can try is get familiar with NCSExpert and check that cruise-control is coded correctly as per Clarker63's suggestion, though cruise was factory-fitted so I feel this has a slim chance of yeilding results.

Keep 'em coming boys
Click to expand...

You could try a battery disconnect to see if it resets the problem.
Rob
 
Smartbear said:
radicalmachine said:
All good suggestions chaps:

mcbutler said:
Your changing up a gear when you are going to slow, the car recognises this and wont allow you to use cruise as revs are too low. If you go 5 mph or so faster I am sure it'll be fine.
It'll do this on hills as well if the revs are too low.
Click to expand...

Doesn't matter how low or high the revs are or how slow or fast I'm going, cruise control gives me '---mph' when attempting to set while in 5th or 6th, or displays the 'cruise-control pre-conditions not met' symbol when changing up from 4th to 5th.

Nictrix said:
Are you putting it in 6th and then engaging cruise or engaging cruise and then changing gears?
Click to expand...

Both, cruise control gives me '---mph' when attempting to set while in 5th or 6th, or displays the 'cruise-control pre-conditions not met' symbol when changing up from 4th to 5th.

ph001 said:
Hmmm it's an odd one. Could your clutch be worn at all (check by putting into top gear, holding the brake lightly and trying to accelerate) if the revs rise with no speed increase yo have a slipping clutch.

Other than that I can only think of a DSC control unit problem :|
Click to expand...

Tried this just now and no slippage, clutch holds well. :driving:

I thought it could perhaps be related to tyre pressure, so topped the air up to 2.4bar in front and 2.9 bar in rear as recommended on the vehicle, but no dice there either. I guess the last thing I can try is get familiar with NCSExpert and check that cruise-control is coded correctly as per Clarker63's suggestion, though cruise was factory-fitted so I feel this has a slim chance of yeilding results.

Keep 'em coming boys
Click to expand...

You could try a battery disconnect to see if it resets the problem.
Rob
Click to expand...

SmartBear May be on to something..the E89 is notorious for spurious issues created by battery / supply related issues.

I would suggest..

Disconnect battery..wait 60 minutes


Reconnect and re-register , did you change capacity? If so update status..

Then try again..

Grasping at straws but in these situations with no other diagnostics ..did you use a code reader in the first place?
 
The question is what is different between a set rpm in 1-2-3-4 and it working to the same RPM in 5-6 and it not working!!
Have you tried in sport as well as comfort?
I think as forum members/owners and not techncians solving this, you may have to bite the bullet and take it to your indy, might be worth calling a few garages and asking for advice, never hurts to try.
 
Another wild stab at it from me:

The '---mph' kind of suggests it doesn't know what the speed is.
How does the Z4 get it's speed reading?
Is it off the gearbox?
Is it possible that there is a problem with a speed sensor?

Now I'm second guessing myself and wondering if that would mean the speedo not registering either?
 
enuff_zed said:
Another wild stab at it from me:

The '---mph' kind of suggests it doesn't know what the speed is.
How does the Z4 get it's speed reading?
Is it off the gearbox?
Is it possible that there is a problem with a speed sensor?

Now I'm second guessing myself and wondering if that would mean the speedo not registering either?
Click to expand...

If that was the case it wouldn’t be working ok from first to fourth :?
Rob
 
Smartbear said:
enuff_zed said:
Another wild stab at it from me:

The '---mph' kind of suggests it doesn't know what the speed is.
How does the Z4 get it's speed reading?
Is it off the gearbox?
Is it possible that there is a problem with a speed sensor?

Now I'm second guessing myself and wondering if that would mean the speedo not registering either?
Click to expand...

If that was the case it wouldn’t be working ok from first to fourth :?
Rob
Click to expand...

Yeah, I kind of thought that too tbh. I did say it was another wild stab.
Just seems to be pointing to something that isn't telling the system what the speed is in those gears?
 
Probably not what you want to hear OP, but Ross (Bowser134 on here) did some work on my 3 Series today and I mentioned your problem to him. In his 15 years at Sytner it's not a problem he has ever encountered.

I hope you can get it sorted as I doubt any of us would ever use cruise in the first 4 gears!
 
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