I wonder whether anyone can help suggest what’s causing the following electrical oddity on a Td6, please?

When the ignition is switched off, the engine stops normally, but the car's other systems do not always shutdown correctly.

When the aberrant behaviour occurs, the first clue is that a couple of seconds after ‘shutdown’ the SRS (Airbag) warning light comes on and stays on at (roughly) half brightness. (That LED I know is switched directly by the Airbag ECU).

Also, when the car has failed to shutdown ‘cleanly’ the wipers, electric windows etc all remain live, although the HVAC and audio systems do shutdown.

When this originally occurred my suspicion was that it was the dreaded steering column failure, but I had it tested by Turner Diagnostics who were sure that the steering column was not at fault.

At that time, on occasions when a clean shut down had not occurred, the car would end up in a ‘halfway house’ situation whereby the central locking would refuse to lock the car, presumably because as far as it was concerned the car was still active.

Worse, was the fact that the ignition system would also hang up, and the key would not be permitted to turn to commence a re-start.

The only cure under these conditions was to disconnect the battery, wait a minute or two, then reconnect, whereupon all systems would reinitialise and normal service would be resumed. (The well known Fuse 18 fix associated with the steering column would never be successful)

At the time all this occurred late last summer, I fitted a complete brand new ignition lock assembly (including key-in sensor) and a new Body Control Unit – but to no avail. I just got used to occasionally having to lift the bonnet, disconnect the battery and reset the system.

Then, without warning, one day last September the problem suddenly apparently cured itself, and the car has behaved impeccably ever since ….. until this week.

In the interim, still suspicious of the steering column, I had bought one of the steering column ECU emulator devices.

So this week as soon as the problem recurred I fitted the device, and the result is interesting:

The failure to shutdown remains, but recovery from the suspended state is easy because the lock barrel is never impeded from turning, thus I can simply restart, wait and then try another shutdown.

At the moment I reckon 50% of shut downs are clean, the remainder end up in suspension.

Having pored over technical manuals relating to both the L322 and its step brother the E53 X5, I can only conclude that perhaps the Immobiliser ECU is at fault – simply because its only part of the start-up and shutdown sequence that hasn’t been changed.

I assume, but haven’t been able to find a document to confirm, that it’s this ECU which emits the shutdown signal over the K Bus, but that it has a discrete connection to the engine ECU which is why the engine always stops as commanded.


Thus my only other idea is to put an oscilloscope on the K Bus to see whether the waveforms are clean, and if not disconnect one ECU at a time until I find the culprit.

In opposition to this theory is that the HVAC system is connected to the K Bus, and it shuts down correctly, but on the other hand it is barely a foot away from the Immobiliser ECU so the signal may not be so dirty...

Anyway after that essay, I’d be grateful for anyone who has read it through to offer any other suggestions on where to look.

Many thanks

When you disconnected the battery did you touch the positive and negative leads together? Touching and holding them together for about 20 seconds has the effect of resetting the ECUs. Followed by doing the steering reset by turning the steering from lock to lock with the engine running.

If you have then my apologies. Can't think what else to suggest. John
2008 Stornoway Grey 3.6 Tdv8 Vogue
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Thanks, yes I have tried both a quick disconnect and a full reset, and either one was enough to reset the system enough to regain full control.

One thing that I have just noticed is that sometimes on a 'clean' shutdown there is a noticeable delay between ignition off and steering column retract - probably 10 or 15 seconds, so something is either doing some thinking, or is sending messages out that are getting corrupted.

Have you tried the seat wiring? The seat wiring and the loom under the carpet, under the front seat/s rub through for a past time and send spurious problems...

Try moving the seat before shutting down? If you have the wherewithal? Take the two front seats out and check the wiring for rub throughs...

Thanks, I hadn't thought about the seats, although they are indeed on the list of K Bus devices.

When I have needed to get under them previously I have simply undone all four bolts and then rocked them backwards so that they are resting on the back seats. That should allow access to inspect the loom on each.

Circumstantially it would also make sense because last autumn I did this whilst checking for water ingress, and that was at about the time that the problem miraculously stopped, but I had never made the connection. Pardon the pun.

When checking the wiring to the seats, there is also a loom under the carpet hidden! That also suffers the same issues sir... 👍

Sounds like a wiring fault. My own TD6 wouldn't fully go to sleep, gear position indicator led would remain on even after being locked and this has only recently been sorted when a wiring fault which related to the EAS going faulty was found and fixed in the wiring loom located in the front footwells.

Since that's been traced and sorted the car goes to sleep correctly.

Many thanks gentlemen.
As soon as the rain stops I'll remove the seats, take out the carpet, and see what lurks beneath...

I thought that I should report back, in case it helps anyone else in the future.

Having ripped out most of the interior, there was no sign of physical damage anywhere, and disconnecting various LRUs from the K Bus made no difference.

Finally I put a Resler Interface on the K Bus and used Navcoder to monitor the bus traffic.

It was clear that the IKE (Instrument Pack) was never shutting down, and was continually broadcasting that the Ignition was in position I even though the ignition was off and the key removed.

My initial worry was that the Instrument Pack had failed, but it receives its Position 1 12V feed straight from the Ignition Switch via Fuse 45, and when having switched off the ignition, I pulled Fuse 45, the IKE dutifully switched off as intended.

Therefore the culprit surely had to be the ignition switch, didn't it?

As I posted previously the ignition switch assembly was replaced last year in an attempt to pin down this problem, but what I had done was to transfer over the original ignition lock barrel.

Land Rover's prices for a new barrel and a couple of keys are obscene, so this afternoon I tried a deep clean of the old barrel.

Having removed just the barrel and given it a thorough bath in Isopropyl Alcohol, I was staggered at the amount of rubbish that has come out, including a lot of fine metallic swarf.

Having refitted the lock barrel, I can report that at the moment the car is behaving itself...

Sounds like the metallic swarf was shorting out the switch electrical contacts and fooling the car into thinking that the key was at position 1?

Mike