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Sounds like either low oil level in box or gearbox ECU gone bad ---- I had a diesel come in that was reluctant to change gear --- I reset xyz switch & cable--- still the same so tried replacement ECU --- done the job

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Have you actually checked the gearbox oil level and condition? I dont see it mentioned? Maybe start with a filter and fluid change?

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Thanks guys, yes I had the trans fluid and filter changed and the gearbox oil was checked four months ago. Would getting another matching ECU be worth it or does it have to be programmed and create more problems since nobody around here knows much about LR's? I see that they are relatively inexpensive on EBay.

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sdoglb wrote:

yes I had the trans fluid and filter changed and the gearbox oil was checked four months ago.

That rings alarm bells with me, you didn't check it yourself so how do you know whoever did it did it properly? Transmission fluid has to be checked cold, in Neutral with the engine running after you have cycled through all the gears. If it was checked with the engine not running, you'll be a least 3 litres short.

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It was changed in June and I checked it 2 weeks ago and it was a little over the dots on the dipstick after I added a half a quart. Also, when ECU is mentioned,to be clear it is the Engine Management Electronic Control Unit behind the battery right?, because obviously there are other ECU's. I tried a swap out of the TCM to no avail. Also, if I can't run through all the gears, would it matter on the dipstick? (yes, I did it neutral and cold).

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Running through the gears makes sure the torque converter and oil cooler is filled, if you check without doing that first the level is about 4 inches above the max mark on the dipstick. It might be worth checking it before starting the engine just to be sure it is that high. If it is still at the max mark then that would suggest the pump isn't pumping the fluid.

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Thanks so much Gilbertd, I will do that right now. Also, I forgot to tell you that the indicator lights are all working on the shifter console, so the XYZ rule out is as you said confirmed. What say you on the Engine Management Electronic Control Unit?

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Update: ok, so I checked the trans level before starting and it was over the 2 dots by a half an inch. Started the truck with TCM hooked up and went through all the gears. Reverse works of course, but all the others have no engagement. Shut the truck off and checked the fluid level. It was at the first dot on the dipstich, which tells me the pump is working regardless of no Drive, 2nd or 3rd or o the other side of the shifter too - only Reverse. Filled it to just below the second dot on the dipstick. Keep in mind, when I unplug the TCM under the drivers seat, the truck will drive in 3rd gear (limp mode). No grinding, no chatter, no burnt smell, no noises...before this all happened or currently.

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Only half an inch? That isn't right. This is mine after it has been standing overnight and before being started

enter image description here

After starting it, running through the gears and checking it in Neutral, it was showing a bit low and only just reaching the top of the black plastic blob. Bottom mark to top mark is only around 250 ml so it doesn't need much at all. It looks like you have insufficient fluid level and/or flow. The level isn't dropping as much as I would expect it to when running. Could be a weak pump or maybe a restriction in the flow in the cooler?

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sdoglb wrote:

……. Shut the truck off and checked the fluid level…..

No! As has been mentioned before, you check the fluid level with the engine running.

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I missed that bit. Yes, it must be checked with the engine running and the gearbox in Neutral. As soon as the gearbox stops turning the fluid drains back into it so the level will be higher. That could mean you are simply low on fluid, showing low when not running and showing normal after it has been run for a while then switched off. If you waited a short time you'd probably see the level rise as more drained back.

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After re-reading all the posts, I did what was suggested again as per instructions. I apologize for not writing earlier that I checked the level when the Rover was running (that's what everyone does normally). Before starting the dipstick looked similar to yours Gilbertd, after starting and running through the gears (which don't work) and checking it in Nuetral while running - the fluid is between the dots.

Guys, I appreciate the insight and wisdom, but I've driven this truck for almost 7 years with the fluid below the first dot at times and over both dots and never experienced what is happening currnetly. The vehicle has been serviced every 3000 miles and fluids have been checked and topped off monthly. So, with that said, if you're telling me that if the transmission (gearbox) is a little low on fluid it will produce the vehicle not to shift into gear, I'm perplexed at that. A faulty pump, restricted flow in the cooler would not produce what I just did and one could not drive it in limp mode I would think. I'm thinking wiring harness or something electronic, but you guys have more experience than me...

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We aren't trying to teach you to suck eggs, just need to be sure the basics are fully covered before getting more involved. I know one owner who's car was driving perfectly until he parked it nose up on a steep driveway and found it wouldn't drive out, no gears at all. When it was finally towed out and onto the flat, it drove perfectly again. That was purely down to a lack of fluid in the gearbox.

Your problem is sounding more electrical if it drives in limp mode with the TCM disconnected yet doesn't with it connected, assuming I've got that right. That sounds as though the TCM isn't allowing it to work for some reason.

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you are correct :) thanks my friend

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https://www.ashcroft-transmissions.co.uk/frequently-asked-questions/4hp22-faq-s.html

My Autobox is now only able to select reverse. Why?
Your A clutch (forward drive) has failed and you will require a replacment autobox.

Sounds like it could be a mechanical issue...

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That is for the non-electronic gearbox as fitted to the earlier Classic and not the electronically controlled one in the P38. I agree it sounds like it could be an A clutch problem but the fact that it drives in limp mode with the electronics disconnected means that the A clutch is engaging then but not when the TCM is connected.

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Or its slipping badly and the ECU can see that and stops drive...

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Theres 4 codes being logged though seraching for the definititions of them comes up with the following
P1775 - might be generic gearbox fault in LR meanings rather than a specific fault
P1777 - step motor (can't see anything much really LR specific for this one maybe again a better definition can be found for this)
P0722 - Output speed sensor
P0740 - TC clutch control circuit

That would seem to point to an electrical issue of some sort rather than a fault with the box itself. Slipping and burnt bands etc would normally contaminate the fuild and make themselves much more obvious? Possible a bad feed to the box which is ok in reverse as its opening less solenoids than in drive?

You mention you checked the wiring - is this a case of looked at it for any obvious damage, or checked with a multimeter or similar method? Best bet may be a test lamp if you can manage to get one hooked up to the connectors? Pulling any of the obvious connectors apart to inspect the bits you can't otherwise see would also be a good idea just in case its gone green and furry inside where you can't see it.

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The electrical document that Marshall uploaded has tests that can be carried out with a multimeter at the connector to the gearbox. I'd be doing them and confirming you are seeing what you should be seeing.

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I'm going to have to get it up on a lift or wait for my mechanic to free his schedule. He mentioned the wiring harness being a possible culprit. I could only check connections and visibly inspect before my vertigo kicked in. So, with that said, I will make sure I mention Marshall's tests and print out these posts for him. I will get back with you when I make some headway. Don't forget me. I really appreciate all of you. Blessings <><