Hippo said:

That fred contains multiple links from different sites but they is all broke'd at the moment.
Give it about 4 hours and there be another link that wurks.

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I don't need the link Hippo. I've found 3 identical copies of the FL1 manual on my portable drive. So I've printed out the wiring diagram, in preparation for another testing session, although this time from the TCM plug.

I still think yer got two faults. The auto's computer can put up with certain faults but when there's two it often can't.

Dodgy wires dun't sound good. The auto's computer should protect against incorrect shifts at speed like 5 to 2, or 4 to 1, at 30mph. Losing control of a solenoid at speed could be the reason why it suddenly drops gears if the wiring int too good and it allows the solenoid to switch oft when the wore "open" or at least goes past the point of too higher a resistance to drive the solenoid.

If you drive normally at 30mph and left foot brake slightly at the same time, does the fault occur?

Hippo said:

I still think yer got two faults.

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Very likely. But without a reader that actually reads the codes, it's impossible to know what they are.
I'm going to be testing the wiring from the TCM to the solenoids over the weekend. I'm also going to check the CAN bus to the ABS ECU too, it's it's coming up with a TCM to ABS CAN failure.

Hippo said:

Dodgy wires dun't sound good.

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No it doesn't. I only spotted them by chance, after I moved the FBH hoses. There's definitely some taping going on there though.

Hippo said:

The auto's computer should protect against incorrect shifts at speed like 5 to 2, or 4 to 1, at 30mph.

Click to expand...

You'd think it would, unless there a damaged wire, which is energizing the wrong solenoid, from another's feed?

Hippo said:

If you drive normally at 30mph and left foot brake slightly at the same time, does the fault occur?

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I've not tried that to be honest. But this strange fault is completely random.

Nodge68 said:

Oddly it behaved impeccably on the way home.

All the solenoids measured within spec, and to be honest I'm not prepared to sling £200 worth of solenoids at it on the off-chance it might or might not fix the issue.

On the plus side, I have found Some "evidence" of tampering with the EDC to box harness. There's an area that's hidden from view, which has been rapped in some form of tape. So I'm thinking that maybe there's a break in the wiring at that point.

I'm also getting a CAN failure between the TCM and ABS ECU. So that's going to need investigation too.

Click to expand...

I got a set of good used solinoids for £50 from eBay.. that was all of them I only changed the duty solinoids..
All mine tested good too.... but changing them fixed me fault of slamming into gears.

Ok. I've done a full check of resistances of the solenoids, at the TCM connection, so to prove the wiring right through the harnesses. All solenoids are in spec, at least when cold. I'm going to drive it a bit and re-check when the box is hot.

I also checked the speed sensors, which are also showing the correct values.

I've seen a couple of potential issues.
There's tape on the main harness, close to the box.
There's also blue tape in the environmental box, which doesn't look factory. Could someone with an automatic look there's for me. It would be helpful.
Here's the blue tape in question.
Thanks

That is standard wiring - my auto and my parents auto both had the splice joints like that in the e box

td4van said:

That is standard wiring - my auto and my parents auto both had the splice joints like that in the e box

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That's good to know. Thanks

Any clue as to the strange operation, or missing CAN at the ABS ECU? Although this hasn't returned after a short drive.

Mine had blue tape anorl. Others it anorl. Example int this fred:

https://www.landyzone.co.uk/land-rover/gearbox-woes.280279/page-2

Eye can put some of my own up later fer comparison if yer need them

If yer leave it in sport mode does the fault occur?

Hippo said:

Eye can put some of my own up later fer comparison if yer need them

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No need Hippo, but thanks for the offer. We'll assume they all have some kind of post production modification.

Hippo said:

If yer leave it in sport mode does the fault occur?

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It's random, so it's difficult to say. I tested it yesterday and it ran faultlessly. I did find some sort of corrosion in the connection to the hall effect position sensor up by the gear lever. I also disconnected the CC ECU, as this was altering the resistance of the CAN line, at the TCM plug. The "CAN failure from TCM" hasn't returned, since unplugging the CC ECU.

My thoughts on this is that unless you have the box/engine to a test bench it's not economical to try and diagnose the fault to sorce. That's why I presumes garages just blitz areas.ie all solinoinds, then test.. ... I just using the force belive you have a solinoid problem....Blitz them n see what happens.

jedi said:

I just using the force belive you have a solinoid problem....Blitz them n see what happens.

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I've got a whole valve block assembly coming next week. I'll test all the solenoids before installing, and see if the problem arises again. One thing I do know, is the CAN failure to the ABS ECU has been cleared by removing CC ECU from the system. I'll see how it behaves next week, but I'll be swapping the solenoids ASAP.

Today I repaired a 2/4 duty solenoid, these fail with an easyish to repair fault.

I also replaced all the box solenoids and the solenoid harness.

I took the opportunity to do a partial fluid change too.

I took it for a 15 mile drive, all of which it behaved impeccably. However the fault was completely random in nature, sometimes not appearing for weeks on my daily commute. However driving for more than 10 miles or so has triggered a misbehaving episode of late. So a 15 mile drive should have been enough to get it to mess about. However it was working as it should, and another peculiar problem it had has vanished. Ever since I've had this TD4, when the box was hot and shifted to 5th, the TC would also lock in, then disengage. Well that seems to have cleared altogether. The box shifts to 5th, without the TC locking momentarily, so I can only assume that was also caused be an iffy solenoid.

So from now on all I can do is use it and see if the box is now sorted.

Pinkies crossed that the gremlin lives no more!!

andyfreelandy said:

Pinkies crossed that the gremlin lives no more!!

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Hopefully. I'm feeling too old for repeated grovelling underneath, then climbing out from underneath and standing on a tool box too work on it from above.

I hope the sump seal stays oil tight too, as no sooner had I started screwing up the 20 odd pan bolts, some fluid decided to find it's way to the bottom flange, running all over the RTV. It's not leaking yet, but time will tell on that. I've also discovered that there's a lot more fuel on the engine than I remember too, so looks like the HP pump is going to need some surgery in the future.

Ok. So it's been 3 months since I replaced all the solenoids with some second hand replacements, the gearbox running faultless aly in all this time.
Yesterday I took our eldest daughter to work which was a 13 mile trip, in heavy traffic through Newquay. On the way back, the gearbox decided it was going to mess around again. Initially I thought the box had flared between 3rd and 4th, which I dose vary occasionally if I'm given it some beans. I backed off the throttle when the engine raced, and it locked into 4th ok. Suddenly without warning it did it again, only this time it slowed down under engine braking. It continued to do the same thing, every time it up changed to 4th. It occured to me that the box was actually selecting 2nd instead of 4th. I pulled over and cycled the ignition, so as to clear down the TCM. As the car accelerated through the gears, the same thing happened, so I switched over to command shift instead of Drive. This actually made no difference, but I could leave the box in 3rd, which prevented the sudden change down to second. Once I was away from the Newquay traffic, I decided to try an up change to 4th. The box again selected 2nd, so I held it there with the engine at 4500 RPM to see what happened. Well after a few hundred yards, the box went into 4th with a huge bang and I get the F4 and HDC error light. I continued to drive it to Wadebridge, which where I was going to meet with family for a bike ride. Once in F4 it ran just fine, although hardly economically with it stuck in 4th.

I parked it up for 4 hours or so, while enjoying the day out.

I wasn't looking forward to the 20 miles drive home, expecting all sorts of games from the box. I used Command Shift all the way, but the box behaved normally, without any messing about. So now I don't know where to go with this. Was it a problem with the gearbox, simply because it was vary hot? Or is it perhaps the TCM, which is getting some form of error, once it's hot.
The day was hot (about 26°C) and I was in stop/start traffic for a good 30 minutes, so I guess the TCM was pretty hot too.

Any ideas are appreciated on this, as I'm all out of ideas myself, and to be honest, the car doesn't warrant loads of cash being spent on it.

So having read the above you say you changed all solenoids. But banging into gear is often a sign that the 2-4 brake duty solenoid is either faulty or has a short of some kind. And it's 2nd and 4th that are playing up.
I would doubt the TCM is at fault, it just doesn't add up. I have experience with them b×ggers, they tend to die completely.
The higher temperatures may have affected the gear change, more due to oil thinning or joints swelling, check the brake duty solenoid first.
I seem to remember there being a check list for the solenoids somewhere.
Mike

Skinny Mike said:

But banging into gear is often a sign that the 2-4 brake duty solenoid is either faulty or has a short of some kind.

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Hi Mike. Nice to see you on again.

This isn't the 2/4 duty solenoid. Yes a failed 2/4 duty solenoid causes slamming into gear. However this is randomly engaging 2nd when it should be engaging 4th. This is different from the initial fault, that prompted me to swap out the solenoids in the first place. I suppose it's possible that the replacement solenoids had a fault, but this I don't know. I'm sure it's a temperature related thing however, as this fault only appeared after it was very hot. It's been absolutely fine since, although it's not been driven far.

Ok. A little update on this issue. After it failed spectacularly when hot the other weekend, I drove it all the follow week completely fault free.

However, as I've been preparing the car for sale later this month, I decided to remove some of the accessories I'd fitted. One of additions was my Sony HU, and a Qi charger shelf. However after reasonably of the centre console, I moved the car to improve access to the front bumper and I got the F4 flash on the dash. Before I parked the car, there was no F4, so I assume it's something I've done.
So I decided to remove the centre console again, and check the plugs by the gear selector. The connections at the sensor board appear to have had some moisture in them at some point. This corrosion has removed the tin plating on the socket pins. So I decided to remove the socket from the circuit board, so I could swap the pins about. Oddly the socket is a 12 way type, but only 5 of the pins are actually used. This made is pretty easy to remove the socket, pull all the pins, then fit corrosion free pins to the locations that actually have wires in them.

After soldering the socket back in, I sat and thought about what this board actually does. I can't imagine it does a great deal. Presumably it is senses the gear selector position, but I don't know to what degree of accuracy. There are some components which I've been unable to identify, but I assume they're hall sensors, as there are magnets on the selector. The position of them appears to be a bit random, so I don't know what these are actually for. There are insufficient wires for each individual sensor to send a signal to TCM, but looking at the ICs on the board, one is a duel NAND gate and the other is a D type Flip Flop. So I'm thinking that this circuit simply tells the TCM that the gear lever is in the sport position. I'm going to research this in more detail today.

I've yet to finish putting the gear selector and centre console back together, but hopefully I'll do that tonight. Then I'll see if all the messing with the socket pins was actually worthwhile.

The logic is explained in Rave. At least that is where I think I read it. It simply looks for lever not in D and not moved to R or 4 and assumes it has moved to right for sport!! Mine goes across to sport but occasionally fails to shift when in sport. Maybe I need to clean up contacts too. Was it hard to remove the board??

andyfreelandy said:

The logic is explained in Rave.

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I'll see if I can find it later .

andyfreelandy said:

. It simply looks for lever not in D and not moved to R or 4 and assumes it has moved to right for sport!!

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That's the kind of thing I was expecting. It's definitely not smart, and not responsible for my selecting 2nd instead of 4th issue.

andyfreelandy said:

Maybe I need to clean up contacts too. Was it hard to remove the board??

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It's not difficult to get out the selector housing, once the housing is out the floor and the rubber sealing boot has been removed. The board is simply held in a couple of slots, with a plastic tab on the side of the housing, that needs so be sprung out for the board to lift.