Good point, he's using a diesel torque converter and bell housing on a 4HP24 so there won't be any change, just a stronger gearbox. The V8 bellhousing wouldn't bolt up to the diesel engine and the larger TC probably wouldn't fit inside the diesel bell housing. I understand the diesel TC and flex plate has only 3 bolts compared with 4 on the V8 so to use the larger TC would involve quite a bit of modification to lots of bits.

Will it? I've changed the original 4HP22 on my 4.0 litre V8 for a 4HP24 with the larger torque converter and other than changes being smoother and at a couple of hundred revs higher, there's no difference.

That's right, I had similar on the Ascot, although it was giving a stored fault on the Nano. Fault was for one ABS sensor (RH Rear in my case) which when I tested it was open circuit. Changed that and everything back to normal. When the fault comes up as soon as you start the car and before moving, it is something failing the self test and, in most cases, it will be a faulty sensor, either open or short circuit.

Agreed, probably just on the limit. Top it up to the max mark but only after you've turned the ignition on and waited for the ABS pump to stop. When the ignition is off, the fluid stored in the accumulator will gradually make it's way back to the reservoir so the level will rise. So if you check the level when the car has been standing for a while, it will be fine but will drop as soon as the pump runs.

That can happen if the TC isn't fully home when you fit the gearbox. RAVE says to stand the gearbox on end when fitting it, which I did, and it slides onto the splines but is a bit wobbly, turn it, it drops about half an inch with a satisfying clunk, is fully engaged and no longer wobbles. As the engine is tilted down at the back, gravity helps with holding the TC in place but a bit of wood shoved in the bellhousing inspection hole ensures it doesn't slip out.

Yes, check the voltage, or wheel speed, with the Nanocom. They should all read exactly the same and as you start to creep forward, they should all start giving the same output at the same time. I've seen one where one sensor was sluggish and was slow to start giving an output which was showing the same fault as you have. A tap with a mallet was all that was needed.

If you've got, or had, an ABS fault, Traction Failure will come up on the dash when you switch off. Is it still doing it or has it now gone away? Chances are the ABS sensor on one wheel has moved and a light tap with a mallet to push it back in will be all that you need do. If it was a failed sensor, it would be detected during the self test when you first switch the ignition on and would also store a fault that the Nano could read.

If the temperature doesn't change then there is a problem with the blend motors. When the ignition is first switched on, they are driven from one end of their travel to the other and the feedback from the blend motor internal potentiometer is checked. If it doesn't show full travel, the HEVAC shuts down the output to the blend motors so they won't move when told to.

If you aren't getting a change in temperature on the pipes to and from the compressor, then chances are you have a slight leak and the refrigerant has leaked away. A simple test is to see if there is any pressure in the system still. Static pressure (when the engine isn't running), should be in the region of 6 bar on both ports, dropping to 2.6 bar on the low port and rising to 10.6 bar on the high port when working. These pressures are at an ambient of 20 degrees C but will give you an idea of what is happening.

Hi and welcome. If you intend keeping the car, you won't go far wrong with a Nanocom (https://www.nanocom-diagnostics.com/product/ncom06-range-rover-p38-edc-diesel-kit), not cheap but it will pay for itself over time. A slightly less capable, computer based, solution is the RSW EASUnlock V4 suite (https://www.rswsolutions.com/index.php/range-rover-p38a).

There's some things you can check with a HEVAC that is giving you the book symbol. Does the temperature change on both sides when you go from Lo to HI, if not, you have a faulty blend motor. Are both blowers working, take the pollen filter covers off and filters out and you can see then down the hole. If only one is working, that will cause a problem. Does it have any refrigerant in it? Leaks from the top left corner of the condenser are common. I know seeing the AC compressor on a diesel isn't easy, but can you see if the clutch is engaging? If it has refrigerant but the clutch doesn't engage, check the connectors on the pressure switches, dirty contacts aren't unknown.

Fusebox is held in place with 3 small bolts, removing those will allow it to be moved. Most people leave the sounder in place and just pull the plug out of it.

The Nanocom documentation (somewhere) does tell you to connect the cable to the unit first before connecting to the OBD port. I seem to remember seeing it when I first got mine although I could never work out why.

An odd one. If the microswitch in the lock barrel has stuck, normally the dash will tell you the key is in even when it isn't when the door is opened. It will also cause a mislock beep when locking. I suppose it is possible that it has failed open circuit so it doesn't detect the key in the ignition and that could set the alarm off when the ignition is switched on, but not as soon as the key is put in the ignition (as it wouldn't know the key has been put in the ignition). The coil around the lock barrel is there to cause the fob to transmit the unlock code as soon as the key is put in the ignition so it resets the immobiliser if passive immobilisation is still enabled. As far as I know it is only the immobiliser that comes on with passive and not the alarm too. Also, if passive is still enabled and the coil has failed so the unlock code isn't being sent, you would get the Engine Disabled message on the dash.

Alarm siren lives just towards the front and under the fusebox. On later cars it was battery backed but by now the NiCd battery in it will be well past its sell by date so it may be that it was trying to draw too much current which popped the fuse. By now it has been unplugged on most cars.....

When he unlocks with the fob, does it turn off the red alarm LED on top of the dash or does it continue flashing?

Connector is supplied with power from Fuse 33. If that has blown, the Nano won't start even.

The suspension on a particular car makes a difference too. When I first needed something to tow a car transporter to the south of France, I went for a 4x4 and, as it was needed at very short notice, I bought a Ford Explorer. Absolutely horrible to tow with. The towbar is attached to the body and that is attached to the wheels by the suspension. Being something designed for the US market, as standard it had suspension that made it handle like a blancmange so attaching the trailer to it made it wallow around like drunken elephant on ice. The trailer had far more control of the car than I did. I used it once and bought a Range Rover Classic LSE two days after getting home.....

tking88 wrote:

Yes, it dips when the AC clutch engages which I understand is normal. But then it continues to do so every 30-60secs.

Perhaps I am being stupid but once the clutch has engaged, does it remain engaged until the ac or engine is turned off?

No it doesn't, it engages every so often to raise the pressure in the system then disengages until the pressure drops to keep it in the correct pressure window. I understand the AC compressor on a diesel is a bit buried but on a V8 where it sits on top of the engine so in easy view, you can watch it continuously engaging and disengaging. As the compressor has no built in regulation, if it was to run all the time the pressure would get far too high.

Does it dip in time with the AC compressor clutch kicking in? On a petrol engine the HEVAC tells the engine ECU that the compressor is about to engage so it can adjust the Idle Air valve to maintain the idle speed. Presumably the diesel has something similar but no idea what. One of our resident diesel experts should be able to tell you.

j_rov wrote:

Richard: Does 300 miles to a take sound normal? I know you run LPG but thinking you must have done the odd full take of unleaded when you are out of LPG?

I think my fuel gauge has only ever got above half full about twice is all the time I've owned the car so have never run on a full tank of petrol. The petrol in the tank is regarded the same as the spare wheel, for use in emergencies only and for as little time as possible. In fact, I've worn out the track on the sender at just below the 1/4 full mark so it either reads below that or above it, when it hits that point it drops off the bottom, the low fuel light comes on and the dash comes up with Fuel Gauge Fault. At that point I bung another 10 litres in just to move the sender (and freshen up the stale petrol).

However, it's a 100 litre petrol tank so that is 22 gallons, 300 miles on 22 gallons works out to 13.6mpg. A bit low but with a twin axle caravan that is going to be higher than the car and being driven with the revs kept down, probably about right. Use Sport mode and give it some revs, travelling slower isn't the most economical as the revs want to be above 2,000 rpm.

Since I changed my gearbox, the new one changes up at higher revs than the old one did and my economy has improved as it is keeping it in the power band more.

I've found the thing that affects fuel consumption more than anything is aerodynamics. Even an empty box trailer will make a hell of a difference, particularly in a headwind, whereas a car transporter loaded with something that is lower than the P38, even though it weighs far more will have much less of an affect. I've also found that using Sport mode and getting the revs up makes quite a difference on hills. The speed can be dropping when the revs are down to around 2k but cause it to drop down a gear and get the revs up to 3k and it will accelerate uphill. If you can keep your speed up to 70mph, the hills don't have much affect at all as the revs are higher. Admittedly that would be illegal in the UK though (sorry officer, it has so much grunt I'd forgotten I was towing).....

Even with a Range Rover Classic on a trailer the other week, my fuel consumption was higher but not ridiculously high.

That is the difference between EER (Energy Efficiency Ratio) and SEER (Seasonal Energy Efficiency Ratio) and COP (Coefficient of Performance) and SCOP (Seasonal Coefficient of Performance). As the efficiency will change with the difference between indoor and outdoor temperature, the seasonal figures take this into account by using a fixed indoor temperature with a varying outdoor temperature and averaging the result. EER and SEER are the differences between energy consumed and energy output, so a unit that draws 1kW to solely convert the energy and outputs 4kW has a EER of 4, whereas COP and SCOP are the output minus the input (the power used to convert the energy but also that used to supply control electronics) so that same unit would have a COP of 3 (4-1).

dave3d wrote:

Ha ha. That would be analogous to having an electric car and towing a diesel generator behind it.

My other half works for Cummins and they have supplied a large number of big diesel generator sets to Australia to power remote EV charging stations......