Ok. So it's not often that I'm stumped by an issue, but this one has stumped me completely.

This morning I had to take our eldest daughter to work, which is nothing unusual. I drove her the 13 miles or so to work, with the car behaving completely normally.
Started the return journey, via Newquay to get fuel. I came up to a roundabout, slowing to an almost stop, before pulling away again. The box thumped down to 1st, at the exact second I put my foot on the throttle to accelerate away. As I rounded the roundabout, I expected to feel the box change up to 2nd as it would normally do. However it stayed in 1st and remained there, even with the engine at 4,000 Rpm. So I limped along at a silly slow speed with the engine spinning at 4K Rpm until I could pull off the carriageway. I tried selecting different gears on Command Shift while limping to the safe stopping place, but box didn't change to a higher gear, although the gear number on LCD did show 2nd when I shifted up. I wasn't going fast enough for 3rd to select anyway. Once stopped, I selected neutral and cycled the ignition, then tried again but it remained stuck in 1st. I then tried reverse and it went backwards ok. I put into park and that worked fine too. So I selected drive and tried again. As the engine got to 1,500 Rpm the box changed up to 2nd, up to 1,500 Rpm and it then went to 3rd then 4th. I was now travelling the speed of the vehicles in front, so after a few seconds box TC locked. I was able to drive the FL1 home without further issues, stopping for fuel on route. 30 minutes later I had take our youngest daughter to football, which was a 20 mile round trip, again the box behaving as it should.

I was thinking that maybe 1st gear clutch got physically stuck into permanent engagement, instead of releasing when it should have. It did change gear at the exact time I accelerated, so the change was more violent than normal.

However things progressed on this fault, so read on for more information.
Any help would be useful.
Maybe @Diesel Do might shed a different angle on this problem.
Cheers.

I've had it stick in 3rd once, but that was sorted out by slowing down and crawling for 100 yards or so til it changed down.
Got to say, this hot weather probably hasn't helped, mines farting about and lumping through gears once it's been running for 20 minutes. It's just not used to dealing with this heat. When it was cooler for those few days it went back to normal.
So I'd say a confused TCM and wouldn't worry too much.
Mike

Sounds like a momentary sticking clutch, could be the jerk, could be the heat. Only fault I have ever had with mine was when I lost reverse (band broke) and it locked the transmission and so wouldn't go backwards even if pushed. Mildly embarrassing as I used to swing across my neighbour's drive and back in !! Had to leave it there with a note on it

Could it be a bad speed sensor? had that problem on my Audi where sometimes it wouldn’t change up from 3rd to 4th that started off doing it randomly until it got gradually worse.

You could try changing the oil it might be too old

Danyou said:

Could it be a bad speed sensor? had that problem on my Audi where sometimes it wouldn’t change up from 3rd to 4th that started off doing it randomly until it got gradually worse.

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The thing is with the autobox speed sensor (VSS) is it likes to throw fault codes even when it's working fine!
So guessing if it's dying or not is a bit difficult.
Mike

Skinny Mike said:

The thing is with the autobox speed sensor (VSS) is it likes to throw fault codes even when it's working fine!
So guessing if it's dying or not is a bit difficult.
Mike

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Oh well,didn’t realise that they were that fickle.

Skinny Mike said:

I've had it stick in 3rd once, but that was sorted out by slowing down and crawling for 100 yards or so til it changed down.

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I'm glad I'm not the only one. I could have coped with it being stuck in 3rd, but being stuck in 1st was a real pain, especially on holiday change over day. I'll monitor the situation and see if it reoccures.
Thanks for the reassuring reply.

andyfreelandy said:

Sounds like a momentary sticking clutch, could be the jerk, could be the heat.

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I'm thinking it was the rough down change, just as I put my foot down to pull away. It definitely went in with a bang, which could well have stuck the clutch. Obviously the TCM didn't know about it, or it would have given me the F4 warning, which it didn't.
Thanks for the reply.

Madmustang said:

You could try changing the oil it might be too old

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It's not the fluid, that's had 3 changes since I've owned it, the last one being under 8,000 miles ago.
Thanks for mentioning it though.

It's the sort of fault yer need to happen on a completely different drive cycle occasion, to know there's an issue or not. I would be hoping for a sticking solenoid value rather than a clutch. Hence why yer could request gear change but it didn't physically happen.

Was there only one LED at a time illuminated on the display by the gear lever?

Accelerating on the cusp of changing gear will give a slightly rougher gear change sadly. The FL1 works ok in hash temperatures. The recent hot spell we've had is well within spec of what it can cope with, before they put an air blast cooler on the auto. Like int middle east territory.

Well this sticking in first has reappeared. It did it last Sunday after a 10 mile drive and today it did it again. This time I was traveling too fast for the TCM to need 1st, but the box went into 1st anyway. This gave the effect that N had been selected, until the hippo had slowed enough for 1st to actually catch up. This is a strange fault indeed. Stopping and selecting R does seem to make the box work again, but this isn't always a practical solution.

Unfortunately my code reader doesn't communicate with the TCM, so it's pure guesswork, unless someone else has a clue.

Knowing not a lot about autoboxes but does it hold 1st or change down too early (can't tell from description)? Only thought I am having is mine holds low gears in cold weather for longer could whatever gives this control be defective? Does using sport mode clear fault?

The clue ere is the bit where yer stationary and it's not changing as requested.

Check the dash always reads ok. Also check only a single led is illuminated by the gear lever, and also correct. This proves the electrical wiring from the lever as the LEDs just light depending on which switch is closed on the barrel connector carrying those signals.

If all that is ok as above then if it were mine I would wait until it does it again then pull over. Then request gear lever options to see if the auto's computer receives the correct request. It should as it uses the use same switches physically on top of the auto, which operate the LEDs by the gear lever. But yer never know if the connection to the actual autos computer is always correct/playing up.

If the autos computer receives the correct command then this breaks up the problem as you'll either get the right reaction (gear change) or not. Like being able to pull away int 2nd gear physically or not.

I appreciate yer dunt have access to a diagnostic that can read the autos computer. Another option would be to manually buzz out those signals to see if they reach the autos computer connector ok.

Well that's how I would do it. When int fault condition see if its the command that's wrong or the reaction to the command that's not happening. It's always a good idea to have a look for engine and and error codes with auto issues. As yer know the auto and engine computers rely on abs computer interaction.

When yer stationary with yer foot ont brake... Yer can hear ticking from the auto gearbox solenoids if yer lie near the front of the car. Be careful yer dun't run anyone over.

When changing lever option... If it changes in/out of gear or a different gear like 1 to 2... You'll hear the ticking tone change, start or stop as appropriate. This will tell you if the gearbox is operating different solenoids in time with lever command request.

The V6 is quiet enough to do this. The Td4 a bit more difficult as it rattles a bit.

Gearbox shift solinoids are on there way out if its got the jatco gearbox

Ok to answer a few questions on this. When this fault occurred last time, I was braking down to about 30 MPH as I approached a roundabout. Seeing the roundabout was clear I put my foot on the throttle and the engine simply raced towards the red line. There was no drive from the engine to the wheels at that speed, like if N had been selected. The gear selector LED showed the correct D position, the also dash displayed D.

I slipped it into manual selection as I was coasting along and tried selecting up the box manually. The sport LED by the lever lit and the dash showed 3 on the LCD, all the while I was slowing down. I manually shifted the lever back down to 1, then to 2 then to 3, this time the LCD only showed 1 and 2, so I assume the TCM knew I wasn't going fast enough for 3 to be selected. At this point I was down to 20 Mph and it was very evident that the box was actually in 1st. The engine was racing away at 3K Rpm and I was traveling at 20. So while travelling in first I moved the selector back into D, then tried the 2/4 lock position. This did nothing, the box remained in 1st, with the engine revving away. So I pulled over (lucky I was on an empty Cornish B road) and stopped completely. I moved the lever from 2/4 lock all the way to P, then back to R. I reverse a couple of yards then stopped, selected D and pulled away. At 15 Mph the box changed to 2, then to 3, up to 4, then up to 5 and the TC locked. It this point I was up to 60 with the box behaving correctly. A mile up the road, I had to slow to pull into the bottom of my lane. It's a steep climb of about 300 ft up a narrow mile long unclassified road, which is more like a track. The speed varies from 15 to 30 Mph on the way up, but the box changed between 2 and 3 quite happily all the way home.

I reversed into my parking space and tried my code reader. It showed not fault codes on a global read, but still had no coms when I checked the TCM. I switched off the engine and went indoors as it was blowing a hooly outside and the rail was going sideways.

I'm thinking that this could well be a sticking solenoid valve, but which one I couldn't guess at. One thing I do know, this fault only seems to occur after I've driven more than about 15 miles. My daily commute is under 10 miles, and it behaves it's self the whole time I do that. It's only done it 3 times in the last 4 months, 2 of which were the last 2 weekends.
I need to get to the bottom of the problem though as an unreliable vehicle is useless to me.

biketeacherdave said:

Gearbox shift solinoids are on there way out if its got the jatco gearbox

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Yes the FL1 gets the Jatco box.

I'm beginning to suspect a sticking solenoid valve myself. However unless it goes open circuit, I've know way of telling which one is causing the issue. I'm very reluctant to spend £200 on a complete set of solenoids, especially if only 1 has an issue.

We did my mates johns one it all started after flushing the gearbox so......changed them all flushed the gearbox new oil all good its a known fault and simple to do diy

biketeacherdave said:

We did my mates johns one it all started after flushing the gearbox so......changed them all flushed the gearbox new oil all good its a known fault and simple to do diy

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Did you ever work out which solenoid it was? I'm wondering is 1 solenoid has I tight spot, which only comes into play occasionally.

Different one for each gear you can look it up and it will tell you but if ones gone the others won't be far behind check the gearbox oil for burning

biketeacherdave said:

Different one for each gear you can look it up and it will tell you but if ones gone the others won't be far behind check the gearbox oil for burning

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The box fluid was horrible when I got it. Not burned, just well past it's sell by date. I flushed it with 3 changes of Dexron 2 and then 3 changes to Carlube ATF-U. It's done under 15K miles since and behaved perfectly, except for the TC clutch, which started to shudder after I overloaded it in the summer of 2017. A couple of tubes of Dr Tranny Shudder Fix cured the shudder on TC engagement and the box has behaved impeccably until August this year, when out the blue it stuck in first, which prompted this thread.
I've not checked the fluid recently, but with under 15K on it, I'm expecting it to be fine.

I do get slight and occasional flair when it goes into 3rd, but I'm putting that down to a worn clutch and the synergy boosting power to more than the TCM is expecting. Of course it could be a sluggish solenoid on the 3rd gear too.

Maybe I'll just bite the bullet and replace all the solenoids.