What does the button on the gear knob of an automatic car do?

NeilF

NeilF

NeilF

Soldato
Joined
15 Nov 2003
Posts
14,473
Location
Marlow
So the button on the front of our SMax automatic gearknob broke off. A new replacement was £300!

I replaced it with a £10 Ebay version, and then managed to source a second hand one.

I'm trying to work out if all is working well, as the button on the front of it seems to do nothing? ie: I can basically move to any gear while driving without needing to press the button.


Should I need to press it when driving to change from [D]rive to [R]everse for example?
 
On most mechanically operated automatic gearboxes, the button should lift the locking pin via a cam or actuator. In more modern automatic shifter mechanisms this will be electronic.

Either way you shouldn't be able to shift from Park to anything else without the button being pushed. The same is likely true for Drive to Reverse, but usually you can shift from Drive to Sport or Drive to Neutral without needing the button.
 
paradigm said:
On most mechanically operated automatic gearboxes, the button should lift the locking pin via a cam or actuator. In more modern automatic shifter mechanisms this will be electronic.

Either way you shouldn't be able to shift from Park to anything else without the button being pushed. The same is likely true for Drive to Reverse, but usually you can shift from Drive to Sport or Drive to Neutral without needing the button.
Click to expand...
To come out of park I have to press the brake pedal.

But the trigger in the gear knob seems to do nothing (& never needs pressing), which seems wrong!?
 
It's broken then. It should lock it in park, also should lock out reverse from neutral, and park from reverse. The brake pedal switch is secondary to this, and usually locks out the shifter button when in park.
 
It might just be that you haven’t fitted the button properly. When I had to take the shifter mechanism apart on the TT (to fix a rattle), the first time I refitted the shifter I missed the fact that the button had a slot that I needed to fit the lifting pin through before pushing the gear lever back down fully onto the mechanism. The button dod nothing when I’d fit it incorrectly.
 
on our mondeo if you dont press the brake you cant operate the knob and move the handle so yes you have something incorrect. may i suggest a haynes manual if you cant get one for your exact vehicle then a mondeo one should be similar and look at the pictures


in fact i take that back as i have just looked in my haynes manual and the automatic transmission section is very sparse more the mechanical side than switch wise ....so you need to take it apart again and have a thorough look , maybe a spring or the likes is missing/dropped down.

i know on a renault auto we had the electric relay that controlled the selector release went faulty and i had to remove the mechanism for a few weeks for the wife to drive it as it would not go into gear, she didnt like using the overide lol. and we didnt want the vehicle laid up while parts were ordered etc but that comprised of springs and pins that needed to be place right to work properly. sorry cant be much help .
 
Last edited:
dont know if the same from the manual
removal selector lever assembly

remove centre console
from inside car, depress the release button in the centre of the selector inner cable end fitting and disengage the end fitting from the balljoint on the selector lever.
pull back the retaining collar and detach the selector cable from the sector lever housing
disconnect wiring connector and undo for nuts too lift out selector housing assembly.

and the usual

refitting is reverse to removal

thats basically all it says grrrrrr maybe makes sense in the vehicle but it sounds as if either a cable should engage or the button should operate a plunger or push a lever so again take apart maybe take some pics?
 
Yeh, looking at the top of the plastic 'gear pole' which the gear knob fits onto, the top 1cm or so has broken off, so there's no hole for the gear knob trigger mechanism to catch into and alter the behaviour. So I'll get a garage to change that selector unit. By chance, when I ordered the replacement knob (off ebay), it came with the entire selector unit, so fingers cross a straight swap over for them :)
 
If you can shift into reverse without pressing anything then you need that sorted before you lunch the autobox and cause an accident when it gets knocked when you're at speed.
 
Luke said:
If you can shift into reverse without pressing anything then you need that sorted before you lunch the autobox and cause an accident when it gets knocked when you're at speed.
Click to expand...
Yeh... As I said above, luckily I have a replacement shifter unit, as it came with the gear knob I bought off ebay.

If the gear knob is £300 new, god knows what the shifter unit is :eek:
 
I had this issue in my Mk4 mondeo some years back. The button somehow broke and then the shifter would move freely (provided the brake pedal was depressed) - thought it was strange but that's the mechanism failure mode.
 
I tend to just use the button any time I cross reverse - though in most technically you don't need to use it going from R to N but do going from N to R and from R to park or vice versa.

In practise I've found, even when the manual says otherwise, quite a few autos will seemingly go in and out of park fine without using the button but so far require it to go from N to R at least when you've come to a stop - I've not tried it while actually driving.
 
You must log in or register to reply here.
Back
Top Bottom