Gearbox problems

Hi all so this weeks problem is gearbox

I know there a few things on here about gearboxes etc but I want to get ppls view on my current issue. My L322 is O2 and done 150k td6

The gearbox runs and works fine through all gears no problems but yesterday I got the old grans fail program come up on the dash, again the gearbox worked fine. I got my test book and got back fault p0374 = gear 4 incorrect ratio. I clears that and it's not come back but then today the grans fault came back and my test book gave me back slipping detected.
Even though my testbook is finding these faults the gearbox works fine. I've checked the oil and it was all ok.

Anyone put anything to this ? I feel it's electrical not mechanical though I no I will be wrong.

any idea on when the gearbox was last replaced if it has been ?

get the oil and filter changed if it hasn't already had it done

torque converters will slip when they get worn, get the car into 5th gear at around 40MPH and accelerate, not to much that it the car kicks down a gear, but just enough to slowly accelerate whilst keeping the gearbox in 5th gear lockup.
in the 5th gear there should be no slipping when the TC is locked in 5th gear, IE no revving up when you accelerate


good luck

As above....

When the box starts going south, the gearbox detects excessive slippage and also differences in input and output speed based on gear selection...if this is to much and the TC can't limit the slip it throws the fault!

Well the box has not been changed and when I got the car they said they had services the box but when I was under the car yesterday there was no evidence of it being serviced as I could not even get the filler plug out and there was a yellow check mark from the factory on the plug. If it is sliping what does that mean new box or a oil change ?

discopaul said:

Well the box has not been changed and when I got the car they said they had services the box but when I was under the car yesterday there was no evidence of it being serviced as I could not even get the filler plug out and there was a yellow check mark from the factory on the plug. If it is sliping what does that mean new box or a oil change ?

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try a fluid and filter change first, the condition of both will give a good indication of wear.

Just spoken to 3 gearbox specialist and they all said the same, now days oil changes on boxes is not a good fix like on older units and range rovers suffer with sticking valves which I've had come up on my testbook so I'm going to see how I get on this weekend over billing and then get it in tue

discopaul said:

Just spoken to 3 gearbox specialist and they all said the same, now days oil changes on boxes is not a good fix like on older units and range rovers suffer with sticking valves which I've had come up on my testbook so I'm going to see how I get on this weekend over billing and then get it in tue

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That's cos they don't like doing it. The box will always last longer with regular oil changes, in fact it was on older boxes where the trouble arose when crap got into the mechanical governor after a late oil change.
Three oil changes each with Lucas Transmission Fix has cured the problems on my P38.

Change the oil ASAP

Cleaner the oil the better !

Up date
Just changed the oil and filter. The oil was a redish brown but no smell or burnt oil, in the pan I expected to see bits of metal but again nothing all normal and the magnet had a light gray gunk on it nothing serious.

I took it for a drive and the box does seam smoother and so far so good no fault even when the box was nice and hot.

I got out 6lts of old oil

discopaul said:

Up date
Just changed the oil and filter. The oil was a redish brown but no smell or burnt oil, in the pan I expected to see bits of metal but again nothing all normal and the magnet had a light gray gunk on it nothing serious.

I took it for a drive and the box does seam smoother and so far so good no fault even when the box was nice and hot.

I got out 6lts of old oil

Click to expand...

All going well change the oil again in a week to make sure it's all flushed out