I have a shifting problem that started a week ago-
Driving home from work, I let off the gas pedal and the transmission shifted into neutral (by itself) and wouldn't shift back into gear until I had the gas pedal down for a few seconds....This repeated for about 10 minutes then all was fine.

I stopped at Lowe's for a bit and upon leaving, it repeated the symptoms for about 10 minutes. The dash has no indication of a transmission problem and my generic code reader shows no codes or may not not see it at all.

My first thought was low fluid level as I haven't checked it since 2011. I thought of doing a hard reboot but I'll wait on responses from here first.

 

Have you any evidence of fluid loss ? The stuff has to go somewhere if there's a leak, and normally leaves a slick on your driveway. This might be very small, but continuing day after day means eventually it will all be gone. Take a few months, though. Puzzling it shows no codes.

Why do you think it has shifted into neutral ? Can you can rev the engine with it in Drive without actually any ? Don't forget there is a torque converter between engine and gearbox. If its internal one-way clutch fails it could cause your symptom

 

Found fluid on the tranny lines at the radiator which is why I think it is losing fluid.

It appears to shift into neutral when I let off the throttle because:
1. When I push down on the throttle pedal the rpms go up and my speedometer continues to drop.
2. I can play with the throttle as if I am sitting in my driveway in Park or Neutral.
3. I have to hold down the throttle for over 5 seconds before it abruptly shifts into gear and speed increases.
4. The above is all that I can recall.
It's been in the garage since that incident as I don't want to induce further damage or any damage to the driveline.

Checked the Shop Manual for Transmission Diagnostics, this is what I got:

 

Clearly the cheapest option is to check the fluid level and maybe then replace fluid and filter.

Drive is transmitted via the torque converter then via an epicyclic gear train in the gearbox. This is applied by high pressure fluid to clutches in the gearbox via electric valves on the Mechatronic assembly.

Can you get any gears by moving lever to the gears position (5,4,3,2), and reverse ?

 

I will check the fluid level at the earliest convenience, I am currently updating systems around the house so it might be awhile.

It is drivable in all gear ranges as long as power is applied, when I let off the throttle it appears to shift into neutral and I have to have the throttle down for over 5 seconds before it shifts back into a gear.

 

reyesl,

In order to avoid catastrophic transmission failure, you really need to resolve this issue before you drive the car again. It does sound as though your fluid could be dangerously low.

As soon as you can, raise it up on four jack stands or two ramps and two jack stands so it is level, and check the fluid at the correct temperature per the manual. Also check the large electrical connector on the rear right upper side of the gearbox for signs of oil contamination and flush both halves with zero-residue electrical contact cleaner spray.

I hope the fluid leak at the cooler line/radiator joint won't be difficult to resolve. Once you've corrected the leak, it would be prudent to do a full transmission fluid flush since the fluid in the gearbox now may be at least slightly burned.

If you do a flush instead of a top-up, you can change to the less-expensive Motorcraft Mercon SP, but if you just top up the fluid for now, I would recommend using ZF Lifeguard 6 to avoid any possible incompatibilities.

Cheers,

Don

 

I've gone through several tech manuals on the tranny from ZF, Jaguar, and Land rover while waiting for the ZF-6 fluid to arrive. Found a few possible causes for the current symptoms, will have to check later. I checked the fluid level yesterday and found the level to be correct (seen signs of past removal of the fill plug).

I attempted to recall what happened on that day the tranny seemed to have malfunctioned--The DCS light flashed then remained on with a "DCS Not Available" msg displayed. As I entered a left turn, the ABS flashed for about a minute, during that time I let-off the throttle and entered a right turn after which the transmission did not provide any power to the drive-train for about 2-3 seconds.

After the transmission oil level check (yesterday), I went for a test drive and had no warning lights for about 20 seconds. The same thing happened with the ABS and DCS but this time after about a mile of straight-road. The transmission worked as should. Parked the car in the garage till I have time to check the wheel speed sensors and other components mentioned in the Workshop Manual.

 

That sounds like an ABS fault - wheel sensor, or whatever - upsetting the trans (or causing torque reduction). Check for ABS codes.

 

Have you ever had the plugs and coils replaced?
These can cause the same symptoms. The jag is bad at detecting these as cel codes.

 

That kinda sounds like the old throttle position sensor malfunction. Or bad battery maybe.

 

Finally had the time to pull my wheels off to check the speed sensors. I unplugged all four sensors, cleaned the tips with a damp towel, cleaned the rear sensor rings with a detail wire brush, connected all four sensors and went for a drive. I don't know which axle had the issue but all is well so far...

 

Front and rear sensors: