chosenview Posted July 25, 2009 Share Posted July 25, 2009 I have a 2001 TD5 Auto Disco and I am trying to understand the function of the Torque Converter lock up. I am trying to do this as a thought engaging the lock up would aid in engine breaking, but now I’m not so sure. I have a volt meter on the orange and white cable (Pin 33) coming out from the Auto ECU which goes to the Lock up solenoid. All it seams to do is energise at 3rd gear and de energise at near standstill. The RAVE cd suggests that it plays a part in Low Range, but I can’t get it to do anything other than engage at 3rd gear. I’m a bit of novice at driving autos so have been practicing left foot braking on descents but if the lock up is not engaged then this seams a waste of time Have I misunderstood the purpose of the lock up? Quote Link to comment Share on other sites More sharing options...
BogMonster Posted July 25, 2009 Share Posted July 25, 2009 The main purpose of lockup is at high road speeds to prevent overheating of the oil in 3rd and 4th and AFAIK it only works in those gears - older hydraulic boxes only had a lockup on 4th. Basically if the TC is slipping all the time on something like a long motorway journey where it may be transmitting near full engine power for a continual period of time then it will cook the oil and this isn't good for the gearbox. Yes it would aid in engine braking and yes it does up to a point but it isn't as effective as it might be if you could lock it in 1st and 2nd for engine braking in those gears as well. I don't know if it practical to modify this to lock in 1st and 2nd, or if there is a reason for not doing it, or even whether the newer more sophisticated boxes such as in the Discovery 3 may have lockups in lower gears as well. Dave Ashcroft is a member of LR4x4 so if we are lucky he might offer some insight into this question as it is an interesting one Quote Link to comment Share on other sites More sharing options...
chosenview Posted July 25, 2009 Author Share Posted July 25, 2009 I was considering a manual overide by energising the lock up solinoid. The worst case I can see is a stall of the engine??? Anyone know better? Steve Quote Link to comment Share on other sites More sharing options...
chosenview Posted July 26, 2009 Author Share Posted July 26, 2009 Also how come the torque converter lock engages when reverse is selected but the car does not stall Quote Link to comment Share on other sites More sharing options...
BogMonster Posted July 26, 2009 Share Posted July 26, 2009 Also how come the torque converter lock engages when reverse is selected but the car does not stall It doesn't engage in reverse, no need unless you plan on reversing long distances at motorway speed Quote Link to comment Share on other sites More sharing options...
chosenview Posted July 26, 2009 Author Share Posted July 26, 2009 Sounds odd, doesn't it. But the Volt metre shows the circuit to the lock solinoid energised when I select reverse. Makes we wonder if I have the right circuit. But it also energises as soon as the car hit's 3rd gear and it's the right colour and place as per the RAVE CD Quote Link to comment Share on other sites More sharing options...
chosenview Posted July 29, 2009 Author Share Posted July 29, 2009 A recheck shows I#ve tapped into the wrong circit - try again Quote Link to comment Share on other sites More sharing options...
Lara Posted August 1, 2009 Share Posted August 1, 2009 I have a lockup override button on the dash, this will lockup the TC in any gear and at any speed providing that the speed is above a pre set wheel speed inside the gearbox ecu, this is about 15k/h in high range and about 1.5 in low box, it is very usefully sometimes but you will actually find that in most circumstances, as long as you are off of the throttle in "over run" situations, the TC is locked by the computer anyway. JE Engineering did mine at my request several years ago. ("Julian's Tomb Raider" if you want to inquire, they will remember) Lara Quote Link to comment Share on other sites More sharing options...
evo828 Posted September 3, 2009 Share Posted September 3, 2009 Lara - I assume it was on the DII TD5 autobox? Have they replaced also the autobox ECU - or they left the stock ECU there and just wired the switch somewhere ? Quote Link to comment Share on other sites More sharing options...
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