Yeti Owners Club banner

1 - 13 of 13 Posts

·
Registered
Joined
·
12 Posts
Discussion Starter #1
Just had the (very expensive) exploding clutch cover plate/gearbox casing repaired...deep joy! Now however I've got a really strange issue. On selection of 6th gear the Maxidot display initially for perhaps a 1/4 of a second shows the correct '6' indication but this then goes blank. Additionally the cruise control won't function. However in all other gears the Maxidot shows correctly and the cruise control works correctly. My guess is that there is a switch or switches on the gearbox to feed information of gear selected to the ECU but cannot find any info on this here or on the web.

Any help will be very appreciated. The garage that did the repair is some ways away and I would like to try to fix if it's simple!!

Cheers Reg.
 

·
Premium Member
Joined
·
5,681 Posts
Pretty sure there is no information from the gearbox to show what gear its in.
It's done by working out the speed and engine revs.
 

·
Administrator
Joined
·
14,216 Posts
They probably forgot to put a sensor or wire back. When I had my rear springs replaced my Xenons became aircraft searchlights and did not "dance" anymore. Took it back and three minutes later it was all back to normal they had rotated a sensor lever out of the way and did not rotate it back into place afterwards.
 

·
Registered
Joined
·
12 Posts
Discussion Starter #4
OK so an update...but first a question!

Can someone please tell me what their rpm is at say 60mph in 6th in a 140hp 2.0 Tdi 4x4?

Spent an hour and a half at the garage while they tried to diagnose the problem. A few possible issues that failed to materialise into a corrective diagnosis. All wires and connections have been made so there is noting amiss there. Urrell is correct there is only the reversing sensor connected to the gearbox so there is no 'gear' information coming from there to the Maxidot/ECU. They did not remove the gear stick inside the car so no possible connections there and, as far as I can tell, there are no electrics there either.....so the info on the Maxidot must come from somewhere else.

However I have now another theory!

The car feels a bit more 'sprightly' and seems to be revving higher when cruising in 6th. This maybe wishful thinking on my part but I wonder if they have installed a gearbox with the final drive ratio intended for the 110hp engine instead of the one for the 140hp which ours is. Trawling through the web I find that there is indeed a difference between these two final drive ratios. So why is the system not allowing the cruise control to engage in 6th?

I wonder if the ECU has a tolerance between engine speed and road speed and if this tolerance is exceeded then the cruise control is disabled....you wouldn't want cruise control engaging in slippery conditions...so perhaps in 6th there is enough difference to prevent engagement but not in the lower gears.

Hence the question..

Thanks a lot

Reg
 

·
Registered
Joined
·
318 Posts
From memory about 1750 I prefer to stay in 5th at 60. 2000 is just below 70 both indicated speed which is 3-4mph low......
If I get out later today I will check.
 

·
Registered
Joined
·
318 Posts
Just checked on the way to the pub.
1650rpm at 60mph indicated.
 

·
Premium Member
Joined
·
1,572 Posts
Pretty sure there is no information from the gearbox to show what gear its in.
It's done by working out the speed and engine revs.
I not sure you are correct with that;

I tried going up and down the box (manual box) low revs and high revs and always the gear selected was displayed on the dash.

It does also show the arrow indicating which gear to change to either up or down, this would explain your second sentence, but there must also be something else that tells the visual indicator on the dash what gear it is actually in.
 

·
Premium Member
Joined
·
5,681 Posts
I tried going up and down the box (manual box) low revs and high revs and always the gear selected was displayed on the dash..
Yes it's because it's working out the ratio between engine revs and road speed to give what gear is selected.
It does not display until the clutch is out when the computer is working out road speed and engine revs to work out what gear it's in.
Same system on my motorcycle.
 
  • Like
Reactions: Dutchman

·
Premium Member
Joined
·
4,027 Posts
I praised Flintstone earlier, but Nick knows so much technical information that it boggles my mind - and he rides a Harley! Much respect to you. Jimmy
 

·
Premium Member
Joined
·
1,572 Posts
Yes it's because it's working out the ratio between engine revs and road speed to give what gear is selected.
It does not display until the clutch is out when the computer is working out road speed and engine revs to work out what gear it's in.
Same system on my motorcycle.
Sorry i doubted you.

That way it calculates it must be more complicated than a simple sensor on the gear stick.
 

·
Premium Member
Joined
·
5,442 Posts
That way it calculates it must be more complicated than a simple sensor on the gear stick.
But a lot cheaper than a series of extra position sensors on the gear selectors for every car built. Once you have figured, calibrated and tested the clever software algorithms, that's it. You only have to do that once, then apply it to millions of VW Group cars. And VW software engineers are quite good at developing clever software, as dieselgate told us.
 
1 - 13 of 13 Posts
Top