2054 (05MY) 4.4 V8 Petrol Vogue BMW M62 L322
FULL S/H - serviced every year without fail.

Transfer Failsafe (3 year problem, still unsolved).
Gearbox rebuilt by Planetgears Peterborough 2 years ago
3 new X/Y switches/cables - latest = 12 months old
Avenger 4x4 Peterborough said low battery voltage so replaced battery 6 months ago.

Current scenario:

Cold start - hit and miss whether this problem happens but more like to than not.
Gear in 'P', Key in, turn key, no engine response, message 'Transfer Failsafe'.

Either...
Take key out and try again. Most times (99%) I get the same response.

Most times...
After not succeeding, key to off, foot on brake, gear to 'N', start car - it always works!
Leave the car to warm up (5-10 mins), turn engine off, gear to 'P', turn engine on - car starts, no 'Transfer Failsafe' message.
(Also - these days I can simply drive off with the 'TF' message still active but the 'limp home' gear action hasn't kicked in, i.e. I can drive at normal speeds, but I tend not to as I don't want to rely on this as always being safe.

Occasionally....
Take the key out then put it back in it will work ok in starting the engine with no other changes, but this is very rare.

Warm start:
Always starts. (Happy days - drive off into the sunset!)

I am not a mechanic but I understand a fair amount of the principles. I've read somewhere something about a Mechatronic unit. Should this be the culprit? Also, I thought there might be a correlation of the error and the brain that recognises the key, unlocks the steering/dashboard and allows the car to start correctly. Could the electronics there be at fault?

Having done the gearbox rebuild and fluids changed at service time each time plus the X/Y switch being replaced 3 times and a new correct LR battery, Im at a loss. Does anyone here have any pointers please.

Cheers.

Phil

Kariba1000 said:

2054 (05MY) 4.4 V8 Petrol Vogue BMW M62 L322
FULL S/H - serviced every year without fail.

Transfer Failsafe (3 year problem, still unsolved).
Gearbox rebuilt by Planetgears Peterborough 2 years ago
3 new X/Y switches/cables - latest = 12 months old
Avenger 4x4 Peterborough said low battery voltage so replaced battery 6 months ago.

Current scenario:

Cold start - hit and miss whether this problem happens but more like to than not.
Gear in 'P', Key in, turn key, no engine response, message 'Transfer Failsafe'.

Either...
Take key out and try again. Most times (99%) I get the same response.

Most times...
After not succeeding, key to off, foot on brake, gear to 'N', start car - it always works!
Leave the car to warm up (5-10 mins), turn engine off, gear to 'P', turn engine on - car starts, no 'Transfer Failsafe' message.
(Also - these days I can simply drive off with the 'TF' message still active but the 'limp home' gear action hasn't kicked in, i.e. I can drive at normal speeds, but I tend not to as I don't want to rely on this as always being safe.

Occasionally....
Take the key out then put it back in it will work ok in starting the engine with no other changes, but this is very rare.

Warm start:
Always starts. (Happy days - drive off into the sunset!)

I am not a mechanic but I understand a fair amount of the principles. I've read somewhere something about a Mechatronic unit. Should this be the culprit? Also, I thought there might be a correlation of the error and the brain that recognises the key, unlocks the steering/dashboard and allows the car to start correctly. Could the electronics there be at fault?

Having done the gearbox rebuild and fluids changed at service time each time plus the X/Y switch being replaced 3 times and a new correct LR battery, Im at a loss. Does anyone here have any pointers please.

Cheers.

Phil

Click to expand...

The intermittent nature of the fault suggests to me a bad earth or other corroded electrical connection. Check the earth strap from engine to chassis, they are known to fail. Check the battery voltage before you start the car, low battery voltage can cause that fault

Datatek said:

The intermittent nature of the fault suggests to me a bad earth or other corroded electrical connection. Check the earth strap from engine to chassis, they are known to fail. Check the battery voltage before you start the car, low battery voltage can cause that fault

Click to expand...

Thanks for this. I'm guessing the low voltage is what was picked up 6 months ago and is still happening despite a new battery.

Kariba1000 said:

Thanks for this. I'm guessing the low voltage is what was picked up 6 months ago and is still happening despite a new battery.

Click to expand...

After standing overnight, you should see at least 12.6 volts at the battery terminals. With the engine running, just after starting, you should see 14.4 volts or more at the battery terminals. You need to check this before going any further.

You have the ZF 5HP24 transmission and the New Venture Gear NV225 transfer box.

The critical thing is whether or not ‘P’ is lit up on the dash when the starter fails to operate?



Can you also just confirm that the message centre displays TRANS. FAILSAFE PROG rather than TRANSFER FAILSAFE?

Phil

@Bemble...

Thanks for that observation; never taken notice, but now I have. The ''P'' is not illuminated when putting the key in first time to start from cold. OK thanks. Once I have switched off and attempt to restart, it appears and everything is 'normal'.

Yes, it is TRANS. FAILSAFE PROG. In was being lazy when I typed the initial message.
Thanks

Phil

Your problem is either a selector cable adjustment issue or an inhibitor switch (xyz switch) issue. Clearly, it’s easiest to check the cable adjustment first. Underneath the vehicle, I would suggest that you slacken off the clamp bolt, slide out the cable, check that the clamp bolt is free to rotate in the lever (this is essential as the lever moves in an arc and the cable in a straight line, so the clamp bolt must be free to pivot) and, after ensuring that the lever on the transmission is in the park position and the gear selector is in the park position, re-tighten the clamp bolt.





If that doesn’t solve the issue, you need to move on to the inhibitor switch. Obviously I’m curious why you’ve had 3 new switches fitted in the past 3 years. I think that you need to check the wiring to the ECU as well as the switch itself.







The switch has five wires connected to five conductive tracks, designated L1, L2, L3, L4 & +ve, and a wiper with five sprung ‘fingers’ sweeps over these tracks. The wiper is splined to the selector shaft.







The ECU interprets the logic of which tracks are lined up in each gear position to determine the position that the driver has moved the shift lever to. This is displayed on the dashboard.



(Note that positions 4, 3 & 2 don't apply to the Range Rover, just P, R, N & D. The switch is also used by BMW, who use all of the positions on some models)

A simple continuity test with a multimeter will confirm if the switch is faulty, according to the table. The connector for the switch is mounted on top of the bellhousing, and you need to remove the plenum chamber to gain access.







However, it’s probably best to complete the continuity test at the transmission ECU itself, rather than at the connector, to ensure that all the wiring is tested.







Pin 31 = +ve (green wire)

Pin 34 = L1 (black wire)

Pin 24 = L2 (orange wire)

Pin 14 = L3 (purple wire)

Pin 4 = L4 (yellow wire)



Phil

@Bemble - Wow, thanks for that very comprehensive reply; much appreciated. It all makes logical sense to me and I will take this with me to Avenger 4x4 and get them to go through it.

Just to mention that you should disconnect the battery before removing the 40-pin ECU connector for the continuity tests and, once the battery is disconnected, you may need to lift the latch gate manually to allow the shift lever to be moved through each gear position, for the checks.



Phil