*** EDIT Although the symptoms were the EAS not responding, Traction, ABS and HDC warnings as described in my first few posts, the root cause of the errors was a faulty locking rear differential motor, with the fault codes per the thread title logged in the rear diff. ECU as read by the iid tool ***


My 2007 4.2SC air suspension is playing up & I could do with some pointers on what to check.

The raise / lower switch on the centre console seems to be disabling itself - re-enabling it via the iid tool (service / test menu) gets it working again but only for a few seconds each time, so I’m guessing something is causing it to lock out.

I can eventually raise to full height, but only after re-enabling the EAS via the iid tool multiple times.

It doesn’t seem to lose height on any corner overnight and I can’t hear or see any obvious airbag leaks.

Battery is 14v when idling, 12.5v with the engine off.

There are no obvious suspension faults reported by the iid tool and the height sensor voltages look to be consistent on all four corners -

Has any liquid found its way onto the TR switches, either a spilt drink or rain? The cause of the comms faults is likely to be the reason why the switch isn't working properly.
The transfer case module isn't sealed so moisture can get into it although I would then expect to see specfic TCCM faults, not just comms faults.

Unconnected to the issue, the RDCM needs to be calibrated which can be done using the GAP tool.

Thanks Graeme - no spills since I’ve had it and no obvious evidence of it happening previously, but it may be worth me pulling the switch out & checking the connector contacts

Ref the rear diff, I’ve run the self test routine on the iid and it completes successfully & I can hear the diff clicking / whirring as it does it, but no change to the error - there doesn’t seem to be a calibration option for the rear diff on my iid menus and I’ve downloaded the latest firmware, unless it’s hidden somewhere less than obvious!

It is reporting that the rear diff ECU is not running the latest update, although again I can’t find where to update it or if it’s possible using the iid tool? Jonathan

2007 Defender 90 XS Hardtop

You would have to apply to GAP to purchase the updated software.

The switch is likely to be internal to the TR module but just removing the module and cleaning all the connector contacts may fix the issue.

Thanks again Graeme - looks like it’s £30 per ECU update file so I’ll look into that, although per the iid tool, I have a few modules that are not on the latest update, not sure if there’s value in updating them all for the sake of it.

Can you give me an idea of where the TR module is located so I can check the connector?

Checked the ABS sensor live values this morning and they’re all reading as I’d expect, when slowly moving the vehicle, the speed value increase consistently on all four wheels.

Also checked the YAW sensor live value and when gently rocking the car, the value fluctuates which I guess means it’s working.

Bit stumped what to check next - am I likely looking for damaged wiring somewhere in the ATCM chain perhaps? Feels like finding a needle in a haystack  Jonathan

2007 Defender 90 XS Hardtop

The TR module is in the centre console - the various TR switches are attached to it.
I've been trying to find it on Microcat 2012 but so far can only find MY10-12.

Edit: Found it and yes, its the whole switch assembly and gearshift surround. Some people have found water to have dripped onto the switches and found its way inside the module.

Having researched the issue further, I believe the problem is directly related to the fault with the locking rear diff actuator, I’ve found an LTB that describes the issue exactly (LTB00228NAS4) and the solution is to fit a new locking diff motor and download the latest diff ECU update, which I’ll obtain from GAP using their Fastlane service, then run the diff self-test procedure on the GAP tool.

R&R of the locking motor according to the LTB is shown as 0.4 hours, not sure I’ll manage it quite that quickly, as I’ll be doing it on the drive opposed a lift.

Will report back once completed.

For anyone that may want to refer to it in the future, LTB is here

https://landroverforums.com/forum/attachme...28nas4.pdf Jonathan

2007 Defender 90 XS Hardtop

Locking rear diff. motor replaced today and pleased to report all faults are now cleared.

Per the LTB, I did need to update the rear diff. ECU with the latest software update from GAP (£30) via the Flash ECU function of the iid tool, then run the rear diff Self Test routine which resets the motor & gear positions relative to each other.

Although the replacement part came with both the motor and the gear housing that bolts to the top of the diff, on inspection, the new gear housing was not the same shape as the original and wouldn’t fit without fouling the chassis once the motor was bolted to it, so something to watch for if you’re doing this job. In any case, the gear housing isn’t the part that fails, so no reason to unbolt it from the diff. as I initially did.

Related, the motor & gear housing when bolted together will not come out from between the diff and the subframe, no matter how you orientate it, so they need to be separated first by removing the four allen bolts - this is tricky as you’re working blind for at least two of them (removing and reinstalling).

Once removed, it was obvious that the motor itself was very stiff when trying to turn the gear, versus the new one which rotated pretty easily, so I guess these do eventually wear out, esp. as I believe its constantly varying the clutches in the diff. even when not fully locked.

Overall a bit of a ball ache of a job, in my case lying on my back on the driveway - in summary, only remove & replace the motor; unplug the connector, remove the diff breather pipe (it’s in the way of removing the motor) and then four awkward hex bolts  Jonathan

2007 Defender 90 XS Hardtop

Many thanks to the above poster for their pointers,just spent the afternoon doing the exact same pig of a job

HDC/abs/suspension inactive warnings all gone and everything working perfectly 👌