hi guys, I have a 1999 discovery td5. The fault I have with the vehicle is, the TC won't lock up when you get up to speed. Sometimes it will take the notion but most of the time it doesn't. Might sound silly but it seems to stand a better chance of working in wet weather. i have read all sorts on internet so I changed the gear box oil twice, and replaced the gearbox filter on the secondchange of oil. No burnt smell from the oil and still a red colour. Will just add, all gear changes are nice and smooth. I have done a stall test and it's around 2800rpm give or take a little just using rev counter in car. From what I have read, TC lock is a ECU sending a message to a solenoid when temp,speed and light throttle is correct. I might have the next bit of info wrong but am I right in thinking that TC lock is manually selected when you put it in to low ratio box? If I am correct, everything seems to be working fine in low ratio. Which makes me think the solenoid isn't faulty or sticking. With it working now and again in wet weather I have the notion it could be electrics at fault. The other reason that makes me think this is, it might lock up at anything between 50mph and 70mph. I have had the vehicle checked for fault codes by Land Rover dealer and the only thing that showed up was Mass air flow and that's now been replaced. If anyone could give me pointers as where to look it would be greatly appreciated. Don't want to go to the expense of putting a second hand or reconditioned box and torque converter in to find it was something silly.
thanks for any help you can throw my way