Hi all,

2006 TD6 Vogue, 120K miles

Hope someone can advise on a torque Converter (TQ) problem - trying to figure out if it's mechanical or electrical.

So here's what's happening:

(1) I start the car, display the 4x4 screen on the infotainment unit. Screen says Hi-range engaged (which it is).

(2) Reverse onto the road, then into Drive and start going up the road. On starting to move forward, 4x4 screen
changes and says Lo-range engaged (but it isn't). *Don't* get the Lo-range indication on the dash. If I move the
gear stick to the left then the dash shows the gear number - there is no sports mode.

(3) Car drives 'normally', going through all 5 gears. I don't think the TQ lock-up clutch engages - small changes to the throttle position cause changes to the revs.

(4) On a long journey, after some time (maybe 20 miles or so), the 4x4 screen changes and says Hi-range engaged
(which it was all along). The TQ lock-up clutch engages - revs drop slightly, and small changes to the throttle
position do not cause a change in revs. Sports mode now available if I move the gear stick to the left.

(5) On some hills at some speeds, revs maybe somewhere in the range 1500 - 2500 rpm, I get the 'TQ needs rebuilding'
symptoms as the car surges a bit and revs drop/increase 100 - 200 rpm. BUT as it's doing this, the 4x4 screen flicks
between Hi-range engaged and Lo-range engaged - it feels like the TQ lock-up clutch is being switched in and out.

So anyone any experience of this? Is it the TQ, and that has feedback through the gearbox ECU to the infotainment
screen? Or could it be the gearbox ECU actually switching the TQ lock-up clutch in and out, and the TQ is actually OK?

Thanks for any help.
Stuart

RRPhil is the man you want. Sounds electrical to me though. When was the box last serviced? 2007 Vogue TDV8 in Zermatt Silver with Charcoal

I haven't got any paperwork to suggest that the gearbox has ever been serviced - so it's quite possible all original, and I'm aware that 120K miles may be pushing it. Just trying to get an idea if this particular problem is electrical or mechanical.

When in low range, there is no sport mode i dont think, its just manual selection of gears ... which is what you seem to be getting. When in high range, the sport mode is available, with the addition of specifying manual selection of gears ... again what you're seeing from the car.

The other components of the car will react to whether in high or low range too. I'd imagine that TQ lockup will disable in low-range mode so that the when off roading, the high torque loads on drivetrain will not snatch at the TQ if it were locked up.

So your issue to me reads like the car is seeing a signal telling it that its in high/low range, and its reacting to that ... so what sends signals related to that ? To me, I'd guess its either going to be the selector on the centre console, or the the sensor that senses whether the transfer box is actually in high or low range.

On the transfer box, there is a sensor which detects at what point the transfer box physically is when it changes from high to low. it has a number of readings IIRC ... something like:

beyond HI
correctly in HI
between Hi and neutral
Neutral
between neutral and LO
correctly in LO
beyond LO

i suppose its possible that if the sensor outputted a wrong position, then systems would react to it.

What happens when you change from hi to lo range and back? Maybe try it a few times to cycle the transfer box through its movements. ( i remember being told by an LR dude that the systems were meant to cycle themselves to prevent being seized ). There is no harm in doing it yourself though. V8 or else ...

Hi/lo switch doesn't work (sorry, should have added that in the original post!) Not an issue in itself as I'm never likely to need lo range ...

If the switch is in op, Is this causing the erratic display I wonder?.

I would replace the switch firstly. That way you should see the correct display when switching.

Is yours not 6 speed?.

I'm with the above - if your hi/lo switch is faulty then it makes some sense you are seeing odd readings. Land Rover Addict
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Well, given that there is a problem with the switch, and that what you describe tallies with the type of behaviors the switch affects ...


... fix the switch ?


Whilst you might not use the lo range, its an integral part of the transfer box ... if it doesn't work, then could that begin to affect the high range also.

Whats wrong with the switch ? in what way does it not work ? V8 or else ...

Just an update - thanks to all who have replied. Another forum member who lives fairly close to me helped me look at and clear the fault codes with his IIDtool. The Hi/Lo switch was completely unresponsive. On clearing the fault codes the Hi/Lo switch would work and we could switch into Lo range and back to Hi range (so the transfer box motor works) but the 4x4 screen and instrument pack messages/lights didn't seem to agree with the box position. Looking at the live values on the IIDtool, it said the box was in Lo range when clearly it was in Hi. A quick drive round the block has brought back the transfer box fault codes 0x5221, 0x5223, 0x52F1, and the Hi/Lo switch does nothing again. Next step is to replace the ECU (which is cheap) and check the wiring between the ECU and the box motor connector, then look at replacing the box motor.

Final update. Took out the battery to get to the transfer box ECU and wiring. Measured resistance between potentiometer wiring signal and ground (or reference voltage - can't remember which) which was OK. But measuring between potentiometer reference voltage and potentiometer ground was open circuit - should be around 5K ohms. Checked wiring between ECU and transfer box motor connector and all OK. So off with transfer box motor and check potentiometer.

Measure resistance between reference voltage and ground connections while rotating potentiometer, and it’s mostly open circuit, only making a connection when the wiper is in certain positions (and not in the high or low positions). Presumably the pressure of the wiper is distorting the track very slightly in certain positions and remaking the bad connection. Got a refurbed motor from 4x4LRO (good service), fitted and all problems solved!