Auto box in two gears at the same time ?

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ianda12

Active Member
Posts
837
Location
Gravesend, Kent
Hi All
My freelander has developed a fault with the auto box. when changing up or down between 2nd and 3rd it momentarily produces a vicious engine breaking as if it is in two gears at once and locking the box before changing.
It also sometimes wont change up from 1st or 2nd until the revs hit about 4000.
I tried a partial fluid change but hasn't made any difference.
These are intermitent faults as sometimes it drives perfect, then the next time I use it they are back again, sometimes they start halfway through a journey. Any ideas not involving petrol and matches would be appreciated.

Thanks
 
Right
I checked the resistances for the solenoids as per Hippo's utube video from the gearbox ECU and all the solenoid readings were O.K.
Three of the sensors were O.K. but the 'Vehicle speed sensor' was open circuit.
To check the wiring I undid the barrel connector(C0932), pulled the cable up a bit and checked from there. The solenoids were O.K. but all four of the sensors are now open circuit.
Put everything back together and tested the car, drove a mile up and down the road and everything seems fine.
Decided I must of broken some wires between the barrel connector and the gearbox whilst moving it, so threaded the connector up to bonnet level, cut of the plastic ribbed cable protector and checked the continuity of the wires from pins 1,2,3 & 4 to just before they go into the gearbox. The wires are O.K. and the sensors/wires are open circuit in the gearbox, but the car is driving fine.
I don't think I have fixed my origonal problem but as it was intermittent I will have to wait and see.
Does anyone know if the gearbox ECU is clever enough to realise the sensor readings are crap and substitute some fail safe readings ?
As the original symtoms are very similar to those of 'Bukko' I am posting on his thread www.landyzone.co.uk/lz/f9/v6-gearbox-ecu-250709.html as well
 
Last edited:
ianda12 said:
Right

Does anyone know if the gearbox ECU is clever enough to realise the sensor readings are crap and substitute some fail safe readings ?
Click to expand...

The TCM (EAT ECU)would throw a DTC Error code if that sensor was open circuit.

P0720 Vehicle speed sensor out of range

From Rave

The EAT ECU will detect sensor failure if the ABS ECU speed signal is more than 25 mph (40 km/h) but the vehicle speed sensor reading is less than 3 mph (5 km/h) for more than two seconds

If a failure of the vehicle speed sensor occurs and the ABS ECU speed signal is functional, the EAT ECU will control
gear shifting using the ABS ECU signal.

If both the vehicle speed sensor and the ABS ECU speed signals fail, the EAT ECU will lock the gearbox in fourth gear (fail-safe mode) and inhibit torque converter lock-up control.
Click to expand...
 
I haven't checked for any error codes as the engine management warning light isn't on !
Its a 2001 v6. I will check for codes though just in case.
Thanks
 
I can only check the engine ECU for error codes and there are none, I am going to try and check the current drawn by the solenoids to see if one ( or more) is sticking. This might not be very easy as the fault is intermittent.
 
I've had this happen to my heap too on down shift as if the brakes are suddenly applied sharply for 1 second then released. I got a drone sound at the same time too. I'm getting deeper into the mystical workings of the auto gearbox and ma heaps ability to control it. How often does your down change drone happen? Mine has done it something like 6 to 10 times if I remember correctly. This is across 500 to 1000 down changes from 3 to 2. Doesn't happen much I know but it's annoying especially with the other intermittent fault I have. My main issue is an intermittent bump on 3 to 2 (covered in my auto fred) which I think I have reduced significantly with slightly smoother changes on all shifts so far. Hence not being about much as this and other things are talking up a lot of my time. Just finished rewiring a change to me monitoring test rig ready to install tomorrow. I don't have any fault codes in the auto or engine computers.
 
Hi Hippo
As it is intermittent sometimes I can drive it 20 miles and its all O.K.
Other times it will happen every change in auto and manual/ sports mode.Worst changing 2nd-3rd or 3rd-2nd but today it was bad and I noticed it on most gear changes.
I don't remember hearing a drone but it certainly 'engine brakes' sharply for a second.
I normally know its not going to work because as I drive off my driveway it doesn't change up out of second (I think), even though the engine is revving to 3000+, I have to put it into sports mode and try changing up a few times to get it going.
I have also noticed that it doesn't always change up into 5th.
Just checked the solenoids, the first 6 on your list (14-18) ohm all read 16.6 ohms and draw 0.67 amps with 11.85 volts applied to them ( can't hear them move or change).
The other 3 (line pressure, brake duty and lock up) all clicked very audibly every time I pulsed them with 11.85volts
Can't be bothered to spend any more money on it so will probably scrap it.:(:(
 
Hi All
Just checked the sensor resistances again, as 3 of them mysteriously went open circuit in the box when I moved the barrel connector (The other one already read open circuit from the ECU, and all four are still open circuit.
 
Last edited:
ianda12 said:
Hi All
Just checked the sensor resistances again, as 3 of them mysteriously went open circuit in the box when I moved the barrel connector (The other one already read open circuit from the ECU, and all four are still open circuit.
Click to expand...

That connector is well known for coming apart slightly.
In Hippo's video he holds it together with a cable tie across two jubilee clips.
I would check mine but I can't find it - it's trapped somewhere since my local *sshole garage put the engine back together badly.

It could well be your problem - and mine!
 
Hi Bukko
I Checked the sensors from that connector and as they read open circuit when all I had done was open the connector and pull the cable up a bit, assumed the cables were brittle and I had broken them. I unthreaded the cable so I could get access to them, cut of the flexible sheath, the cables all looked O.K.
So I stuck pins through the insulation into the cores for the sensors just before they disappear into the box. The cables all have contunuity back to the ECU, but the sensors all read open circuit in the box. I was even using an intrinsically safe multimeter which can only give out about 20mA on the ohms ranges so I couldn't of damaged the sensors checking them. I am at a complete loss as to why that has happened, or why it sometimes drives perfectly with no sensor readings to the ECU.
 
ianda12 said:
Hi Bukko
I Checked the sensors from that connector and as they read open circuit when all I had done was open the connector and pull the cable up a bit, assumed the cables were brittle and I had broken them. I unthreaded the cable so I could get access to them, cut of the flexible sheath, the cables all looked O.K.
So I stuck pins through the insulation into the cores for the sensors just before they disappear into the box. The cables all have contunuity back to the ECU, but the sensors all read open circuit in the box. I was even using an intrinsically safe multimeter which can only give out about 20mA on the ohms ranges so I couldn't of damaged the sensors checking them. I am at a complete loss as to why that has happened, or why it sometimes drives perfectly with no sensor readings to the ECU.
Click to expand...


Did you try testing the sensor at the TCM connection instead of at the barrel connection? This would confirm if you do have an open circuit or not.
 
Hi Zefrench
The first test I did at the TCM and all read correct except the speed sensor which was open circuit.
I then dissconnected the barrel connector to test from there to eliminate the part of the wiring loom from the barrel connector to the TCM.
The wiring was O.K., but from then on all sensors read open circuit, tested from where the wires go into the autobox. Makes no sense to me !!
 
Further update. Based on posting in the Volkswagen 09A forums, and reading the 232 self study PDF, I would guess that if all the electrical test are correct that one of those solenoids went bad mechanically :

THT500040 - N282 - 2-4 Brake Timing Solenoid
THT500050 - N283 - 2-4 brake duty solenoid valve


Now the N282 is on/off and you say it makes an audible click when tested I would not change it. However N283 is modulated and it's "action" changes based on the amount of voltage put to it. If it test fine electrically. I wonder if it is sticking or failed mechanically. I wonder how hard to test and measure varying hydronic pressure during gear change.

I am not sure which of the two taps to use for that one. Then again I personally hate growing parts at things. I wonder how much that Solenoid is by itself in the uk.
 
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