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'Transmission 1 to 2 seconds delay when you shift it from P or N into D...'
A 305/xj12 I am contemplating going to look at has a transmission that has '1÷2 seconds delay when you shift it from P or N into D'. Anyone familiar with this issue?
I never have researched the possible causes, I just live with it. It has not worsened or caused any other running problems that I can tell. However, I would like to solve it. We need to find the root cause. The exhaust center section has to come out to drop the pan, so not such a causal affair.
Interestingly, my car has an annoying harsh engagement of 'Reverse'. Its the opposite of the slow engagement to 'Drive'. So after all these years, it's finally time to look into these issues.
interesting! It sounds as though it may be a gearbox specific issue rather than a X305 one. I'm assuming the one I am going to appraise has a GM 4L80-E unit.
I had thought about the possibility of low fluid pressure or stuck ball valves in the valve body. Stuck (or missing) ball valves might explain my harsh engagement into Reverse.
Another thought: since the center exhaust section has to be removed to drop the pan and replace the filter, perhaps the filter hasn't ever been replaced! I assumed my trans had a relatively new filter in it at 66k (at the 60k service) when I bought the car, since it had always been serviced at the dealer up to that point. But the issue was present then too. I didn't really investigate. It wasn't a deal breaker for me.
My fluid changes were done via the repeated drain and fill method. Just finished a series. There was no improvement in gear engagement after the fluid flushes.
First things first, I think the filter must be replaced in order to rule out that simple factor. My car is due for it now anyways at 95k.
Last edited by SleekJag12; Mar 20, 2018 at 03:10 AM.
I spent some time on youtube last night watching videos about GM 4L80-E rebuilds, transgo shift kit installs and general maintenance, nothing specific to the sticky shift yet. Replacing a badly clogged filter could free up fluids but a long shift delay suggests some sort of solenoid issue to me? I'll continue to research...
Transmission OBD read if anything is flagged ? Internal shift control module reconditioning by removing it and it's solenoids to soak in solvent and maybe free up a sticky check valve that causes a slow muscle fluid response to shift command ?
Just spit balling .
On the good side is that transmission is common and my be cheap so at least you get the engine and it's components .
Reliability during bringing it home in that condition is a factor to consider if it is even an issue .
Transmission OBD read if anything is flagged ? Internal shift control module reconditioning by removing it and it's solenoids to soak in solvent and maybe free up a sticky check valve that causes a slow muscle fluid response to shift command ?
Just spit balling .
On the good side is that transmission is common and my be cheap so at least you get the engine and it's components .
Reliability during bringing it home in that condition is a factor to consider if it is even an issue .
The car is a flight away on west coast, trying to read up as much as possible in the manual you gave me link to above (thanks!), watching youtube rebuild videos to understand idiosyncrasies. The current long term owner says it has been like this for years and operates perfectly, and he has driven it all over the US....
Thanks!
Is there an overall workshop manual for the 96 xj12 anywhere online? Would be useful for more general troubleshooting...I like to read up as much as possible prior to the side of road head scratching that inevitably happens sooner or later...
Without following the fluid logic to find the target binding check valve ( if it is ) to enable muscle pressure to do it's thing if you had a good backup manual gate gear selection with no lag that would be a confidence booster to get it home .On the other transmission like mine for the X300 series there is a rotary manual shifter as a screw torque bit on the shifter plate other then taking the J gates into the 1 2 3 positions besides the normal D position
You might find out more information on this screw torque bit feature ( if it has this 3rd shifting option ) and a overhaul manual in the X300 section as the same GM 4L80-E transmission is used in the supercharged AJ16 engine beyond the normally aspirated like M'Lady Penelope's AJ16
Without following the fluid logic to find the target binding check valve ( if it is ) to enable muscle pressure to do it's thing if you had a good backup manual gate gear selection with no lag that would be a confidence booster to get it home .On the other transmission like mine for the X300 series there is a rotary manual shifter as a screw torque bit on the shifter plate other then taking the J gates into the 1 2 3 positions besides the normal D position
You might find out more information on this screw torque bit feature ( if it has this 3rd shifting option ) and a overhaul manual in the X300 section as the same GM 4L80-E transmission is used in the supercharged AJ16 engine beyond the normally aspirated like M'Lady Penelope's AJ16
THANK YOU Parker, for finding and sharing that Technical Service Bulletin. I was never aware of it all this time.
Jaguar made a good effort to integrate the 4L80-E for use in the first-gen XJR and last-gen XJ12. But like any new design and first build, it wasn't perfect. They must have started hearing about this issue almost right away. They must have been working frantically (with GM) to identify and correct the issues in order to keep the "new model" Jaguar buyers somewhat happy, as they were dropping 70-80k on these cars (or investing in pricey leases), a lot in 1990s money.
Their simplest solution was to replace the entire transmission with a "revised specification" transmission. An all-day project. Shipping transmissions in, and replacing them was "easier" than having a technician go into the unit while in the car, and run tests, replace components according to TSBs, etc. That tells me there were multiple issues, and to assure consistency and correction, an updated replacement was the only best option. And finding out exactly what was done to the updated transmissions these days, seems nearly impossible.
This is pretty heavy news. Although on a much smaller scale, and not a debilitating defect, it was the pre-cursor to the engine replacements that became necessary with the first-gen V8 a few years later.
Ford had some rotten luck with Jaguar back then! Not really anyone's fault, it happens. The 4L80-E was proven and generally works great in the few Jaguars that used it. The new Jaguar V8 was considered an advanced design, more refined, powerful and efficient than it's predecessors at Jaguar. They really put some money into improving the brand.
For me, the case is closed. I can live with it, like I have been. But I will still replace the pan filter and shift solenoids, just to be sure. I will make sure the ball valves are all accounted for, best I can. I suppose my particular car didn't show this problem until after the warranty expired, and the cost of the dealer replacement was out of the question.
Another item of note is that the Transmission Control Module needed a software update according to TSB 08.2-01, 10/1995. Document attached. I checked my car's module and it was done in April 1996. The update applies to XJRs too.
Let's see what 1 of 19 has to say. I think he's looking under all his cars right now to see if they have the orange paint spots on the transmission!
Might be worth asking round at Jag dealer service departments to see if they have any old files on transmission troubleshooting prior to the decision to replace the old unit, you never know your luck...I'd like to know if it's an electronics or physical issue....
Without following the fluid logic to find the target binding check valve ( if it is ) to enable muscle pressure to do it's thing if you had a good backup manual gate gear selection with no lag that would be a confidence booster to get it home .On the other transmission like mine for the X300 series there is a rotary manual shifter as a screw torque bit on the shifter plate other then taking the J gates into the 1 2 3 positions besides the normal D position
You might find out more information on this screw torque bit feature ( if it has this 3rd shifting option ) and a overhaul manual in the X300 section as the same GM 4L80-E transmission is used in the supercharged AJ16 engine beyond the normally aspirated like M'Lady Penelope's AJ16
As far as I know, the torx bit on the shifter plate is only a cover screw for the shifter park lock. You can press a small screwdriver into the hole to release the catch and move the lever out of park, without the key in or ignition on. Right? There isn't any other shifting function available there.
The transmission in the XJ12 is designed to engage 2nd gear when shifting into Drive, when in Normal mode. This action is where the delay occurs. When I set the trans to Sport mode, it engages 1st gear more quickly than engaging 2nd in Normal mode (but still just a shade longer than average). I think I'll try using sport mode more often. Unfortunately, the first gear whine is present, as it is in virtually ALL 4L80-Es. But I can live with that. The car comes off the line very quickly in Sport mode.
The TSB regarding delayed engagement makes no mention of checking the TCM, or anything else for that matter! The issues could have been electrical and/or mechanical but apparently there was no need to replace the TCM. The software update came out as a separate TSB, and is not mentioned in the delayed engagement TSB. I wonder if that software update was prompted by the delayed engagement issue in some way, perhaps as an attempt to alleviate it. Which didn't work.
Oliver, I suppose you will want to shop for an XJ12 with the revised transmission and the software update. However, I don't believe the delayed engagement issue to be a sign of any kind of impending failure. The transmission simply takes its time to engage. Don't press the gas pedal until it is engaged. It's a Jaguar, after all, no need to be in any hurry!
Oliver, I suppose you will want to shop for an XJ12 with the revised transmission and the software update. However, I don't believe the delayed engagement issue to be a sign of any kind of impending failure. The transmission simply takes its time to engage. Don't press the gas pedal until it is engaged. It's a Jaguar, after all, no need to be in any hurry!
The current owner of the xj12 I'm interested in has said the gearbox has had this 'feature' for as long as he can remember but it otherwise functions perfectly so I'm pretty sure this isn't an 'orange spot special!'
If you could get under a pre purchase xj12 (if you can ever find them) to look for the orange spot (or even better see the gearbox replacement in service history) that would be useful intel before taking the plunge...
'Transmission 1 to 2 seconds delay when you shift it from P or N into D...'
On the other transmission like mine for the X300 series there is a rotary manual shifter as a screw torque bit on the shifter plate other then taking the J gates into the 1 2 3 positions besides the normal D position
