Disco 2 Manual/Tiptronic gearbox

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DrecklyD2 said:
You’ll need a switch, some wire, and a standard 30amp relay.
The reason for using a relay instead of a large resistor is it acts as a fail safe for the TCU. Even though you have manually energised the TC lockup the TCU still thinks it’s in control and will when it thinks it’s right will energise the TC. If a resistor is used it will short and put it in limp mode. So the TCU thinks it’s doing its job as it should.
The other reason is the TCU is constantly monitoring the system, if you splice in or cut the TC wire it will throw a fault and again enter limp mode. With the relay connected the TCU sees this as a connection to the Solenoid Valve as thinks all is well. Ok now I have bored the hell out of you here’s what you need to do.
1. Find pin 32 on the TCU, cut this wire but not too tight to the TCU.
2. Connect the wire from pin 32 to one of the pins on the relay. Either the + or - that energises the relay.
3. Connect a wire from the opposite side of the one you have just connected on the relay and splice it in to the wire on pin 53 which is the power supply to the solenoids. This connection allows the self diagnostics to see what it thinks is the solenoid valve.
4. Connect a length of wire to the wire that was connected to pin 32. Connect this to one terminal on your switch and the other to a good earth.
5. When you operate the switch you are supplying a direct ground to the TC solenoid valve which will energise it and lock your TC. You can do this in any gear, but don’t let it change gear when locked.
I hope all this makes sense, but let me know how you get on and if you have any questions please feel to ask.
Cheers
Tom.
Click to expand...
Does this look good and do you think it would work?
 

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I'm guessing RE? I wass thinking when my wife drives it so that she does not need to think about locking the TC when driving.
Does 32 give a 12v Signal or power to the solenoid?
 
Infantry grunt.
I'll have to check and get back to you on that.
I know the solenoids have a permanent live feed and the TCU uses the earth to switch the solenoid.
If my wife drives my truck I just un plug the relay and join the wires.
Could be done with a switch quite easily.
 
I dont want to interfere in this mod as i can't try myself but based on the autobox operation mode which i know in theory i can tell you that this way when you switch it on the lock up solenoid will be energised(all the solenoids are getting permanent power feed from pin 53 and earth to be activated when needed then when the switch is off the system goes back to normal operation). I'm really amazed that the ECU does not identify the false lock-up but as the OP who drives this way said it works without fault codes i cant contradict that. Good luck, let us know how it works for you too cos it's an interesting mod. In theory, it depends much on how you'll use this cos if at one point the conditions for the ECU(TPS/rpm inputs) will be proper to lock up while your switch is on then normally it must recognise the open circuit for that solenoid and go to default that's why i was suspicios... maybe it "feels" the open circuit anyway that's why the OP connected a relay's coil there
 
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On a second thought, your scheme as to work like the OP did it without relay should look like this IMO... as the ECU to not get open circuit there when the switch is on

1700002839018.jpeg
 
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sierrafery said:
I dont want to interfere in this mod as i can't try myself but based on the autobox operation mode which i know in theory i can tell you that this way when you switch it on the lock up solenoid will be energised(all the solenoids are getting permanent power feed from pin 53 and earth to be activated when needed then when the switch is off the system goes back to normal operation). I'm really amazed that the ECU does not identify the false lock-up but as the OP who drives this way said it works without fault codes i cant contradict that. Good luck, let us know how it works for you too cos it's an interesting mod. In theory, it depends much on how you'll use this cos if at one point the conditions for the ECU(TPS/rpm inputs) will be proper to lock up while your switch is on then normally it must recognise the open circuit for that solenoid and go to default that's why i was suspicios... maybe it "feels" the open circuit anyway that's why the OP connected a relay's coil there
Click to expand...
One of the main reasons for no faults is the use of the relay.
It does two operations in one.
Firstly self diagnostics sees a connection and thinks its connected to the solenoid.
Secondly, when the TCU gets all the relevant information and sends the earth connection to what it thinks is the solenoid when in fact it energises the relay and it thinks all is well.
Hope that makes sense.
 
Iwandavies351 said:
Thank you, i will try and see if it works, great, if not, nothing lost, other than gearbox exploding. 🤪
Click to expand...
Luckily the gearbox will not explode it will go into limp mode. Let me know how you get on.
I have been using this setup now for a very long time with absolutely no issues or faults and it works perfectly for me especially when towing down steep hills.
 
Have you allowed it to change gear when the TC lockup is angaged, if so, what happened? Any adivice on how best to drive, what gear lever postion ect.
 
I have changed gear with it locked and it was smooth as a normal change but I don't make a habit of it.
I usually use it in 3rd bring the rpm uo to 2000, then let it cruise to 1500 and engage the TC.
It's all about learning the best rpm for each gear.
 
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