The recently acquired ‘03 Vogue TD6 (145k miles) has been nothing but trouble-free joyful motoring (not)

Backdrop/preamble:

Acquired the vehicle already with an array of HDC/ABS related warning lights. Purchased the RSW scanner tool and resat various of fault codes across most ECUs. It seemed most were trivial and likely attributable to voltage drop and/or the battery going bad (i.e. repeated disconnecting, jumping, charging, etc). I replaced the battery with a (provisional) 50Ah (small) battery and the car functioned like it should (free of any warning lights) for a couple of weeks. Just bought a 110Ah Varta unit to drop in.

Then the key door remote stopped working, and about a week later the main battery suddenly was drained overnight (down to 5-6V). Upon charging the battery (while connected), a relay (?) started going frantic from inside the “E-box”. Disconnecting/reconnecting the battery solved this.

Ever since this last occurrence, the car now won’t start/crank. Freshly charged battery (12.5V), a different battery as well as jumper leads from a running vehicle (charging @ 13-14V) makes no difference.

Key turn fine through all ignition positions, but there is no cranking action or click from starter relay/solenoid (nor that electric jerking sound from insufficient voltage or bad ground). Column lock disengages and all other power functions seem to work.

I have two sets of (fairly worn) keys, both work/turn in the door and ignition. One key (the least worn) have had functioning remote central locking, until recently. Checked battery condition in both remotes and voltage checked out fine (done within the 2 minute (?) window necessary to avoid resyncing). I guess there should not be any causality between central lock and ignition/immobilizer, as I understand the immobilizer transponder works independently from the central locking system and its battery?

Also, having attempted the resyncing procedure for the keys (dozens of times), all I get is ten flashes from the remote’s red LED. No confirmation from door locks. No information in display other than acknowledging the key when inserted (‘key in ignition lock’).

Checked all fuses (glove box and quarter panel) and tried to “wiggle” the shifter (i.e. back and forth between D, N and P) while attempting to crank in order to test neutral safety switch. Also tried pulling/reconnecting fuse #18. There are no codes stored on the immobilizer ECU.

Any advice is highly appreciated!

Welcome to the forum
Just as a starter to try.
Are you sure the battery terminals are fully tight after changing the battery?
Is the battery earth connection to the body metalwork ok?

and after that I would check that the starter cable is properly connected, then check that the starter motor actually works (direct wiring from a battery, after disconnecting from car) .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

If it was immobilised you would have a fault code on the Allcomms from memory under the immobiliser section. The EWS immobiliser has to be synced with the engine ECU. Allcomms can read the fault but can’t program the link.
The transponder in the key talks to the ignition barrel surround so if the key turns to the cranking position and you get all the lights then it could be the ignition barrel, immobilised or another wiring fault as above. The alarm and central locking is a separate system to the key transponder , steering lock, immobiliser, engine ECU and ignition barrel which all talk to each other.
There is a electrical library available as part of Rave.
Do you have any faults showing on your Allcomms?

Thanks for the warm welcome and suggestions!

Terminals are fine and most of the cables looks sound/new. I even ground down the gap some more to be sure that they clamp down well.

Checking voltage to starter (and applying voltage directly) would be my next step. But it doesn't seem at all that easy to access the starter? How much stuff has to come of?

Is it given that the transponder coil (barrel surround) is functioning like it should when it allows the key to be turned and electronics to be turned on? I guess if there is no voltage on starter the problem would likely be limited to the link between the starter motor and immobilizer ECU? Where is the starter solenoid located on TD6s (on V8s it appear to be behind the battery)?

Will recheck fault codes now that it has been sitting with the battery connected for a while (deleted most last time that was due to voltage drop).

I got the following six codes:

Transfer Box Module: “Battery undervoltage (0x5212)”

Engine Control Module: “Electric ECU fan”

Instrument Pack Module: “EBV function fault received from ABS ECU”

ABS Module: “Temporary system deactivation” and “Steering angle sensor ECU internal fault”

Still nothing on the immobilizer ECU, and I believe most of these can be attributed to low voltage (measured 5,6V again, there's a drain somewhere).

I wrangled the box fresh Varta in there with 12,7V across the terminals only to make zero difference. Also measured 0V (i.e. 0,4-0,7V) between ground and the + cable on the solenoid atop the starter when trying to crank.

Transfer Box Module: “Battery undervoltage (0x5212)”
(battery)

Engine Control Module: “Electric ECU fan”
(this was probably the noise coming from the big black ECU box)

Instrument Pack Module: “EBV function fault received from ABS ECU”
(OK to ignore)

ABS Module: “Temporary system deactivation” and “Steering angle sensor ECU internal fault”
(probably battery)

Still nothing on the immobilizer ECU, and I believe most of these can be attributed to low voltage (measured 5,6V again, there's a drain somewhere).

You may need to "lock" the car, and start pulling fuses, with an ammeter / clamp meter on the negative lead to the battery

SEE HERE
(lots to read but got there in the end) .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

As I was suspecting a battery drain since I got the car, (attempting to) measure the current draw was one of the first things I did. Of course, not knowing the shutdown period and such I was not able to get any practical readings.

The more urgent matter now tho, is that the pile won't start. Could the "lazy starting" function somehow be the culprit?

Also, any suggestions on the non-functioning central locking?

Any more suggestions or people that have had similar issues? How do I go about diagnosing the immobilizer ECU itself?

Going back to the beginning, can you lock and unlock it with the alarm fob?

If you unlock the car with the key, does the alarm sound ?

The ignition barrel can fail, sometimes giving the key a wiggle in the barrel will work temporarily.

Diagnostics like a faultmate would tell you more as to what status the various systems are at.

Have you got breakdown cover ....?

Are you sure the battery is now fully charged, have you tried jumping it from another car as if the battery is low it wont even try to start but will give you lights and unlock ignition.

You have fuse in the E Box and behind the glove box and also behind the battery I believe which are the main power supplies.

You need to check every single fuse in the fuse box which i guess you have done in the glove box but there are other fuses which could have been compromised when changing the battery.
I have attached some extracts from Rave Electronics manual
manual can be downloaded here
http://duud.ee/LR-manualid/Range_Rover_Ele...y_L322.pdf

Click image to enlarge

One thing that has happened to me recently, I was getting the same and threw me completely, there was no clicking .I directly linked the starter, crossing the feed to the solenoid . It was the solenoid that had broken down and so I bought a s/h starter and refurbished it taking it apart and rebuilding , jobs a good one.
The theory of the draining of the battery can come from a bad diode in the alternator , it will be warm in the morning after sitting all night. This can be draining the battery. Hope that helps.

Alfapat nailed it! I shorted the prongs on the solenoid with a screwdriver and the car fired up. Never had I imagined that the culprit would be a component this simple.

I have searched around for separate solenoids or rebuild kits, but it seems starters are only sold as a complete package. How did you go about refurbishing your? I guess the plunger functions normally and the fault lies in the control current, somehow?

Also, thanks for your input, holidaychicken!

I bought a complete unit , stripped both down and cleaned all components lightly lubricating moving parts but not in motor.It was mostly carbon holding up the solenoid , but turns twice as fast now and sounds like new.I ran a bench test first and could see what was happening , just take pics to confirm your rebuild , I still have some parts of the old motor, thats your best way of solving it , my only issue was snapping a stud in the starter carcase as they were extremely tight, good access I discovered after bending over engine to get the bolts off the engine block for four hours, was to take the main middle part off the bulkhead LOL and thought why did I not do that earlier!

Did you buy a used unit? So the solenoid casing was just filled with gunk/debris? Did you find that you needed the extra starter/solenoid, or could the original one suffice if you cleaned it up?

I see junkyards sell them for about 140 GBP locally, and I'm wondering if I should opt for a new £99 off of eBay (https://www.ebay.co.uk/itm/RANGE-ROVER-L322-TD6-3-0-2002-2006-DIESEL-BRAND-NEW-STARTER-MOTOR-NAD000090/152016434484?_trkparms=aid%3D555017%26algo%3DPL.CASSINI%26ao%3D1%26asc%3D20151016114640%26meid%3D692099a331924d44855cd483bd08d2ae%26pid%3D100507%26rk%3D1%26rkt%3D1%26%26itm%3D152016434484&_trksid=p2045573.c100507.m3226) or a £22 (about £65 after S&H) (https://www.ebay.co.uk/itm/BMW-530-3-0-Td6-Starter-Motor-0001109025/123138706963?hash=item1caba38e13:g:UlwAAOSw241YZkYl).

Paddock wants 180 GBP for a Prestolite unit (https://www.paddockspares.com/nad000090-starter-motor-td6.html).

The "no-brand" eBay unit has a 1yr warranty, but I would venture to guess it being of Chinese/inferior quality?

Any suggestions?

It was s/h from a scrap yard £35 . If you remember I broke or snapped a stud in it so getting a starter body was the first thing and from then cleaned up , there was a good deal crud /dust etc and I made it all up again . Worked a treat , you don’t need to spend as much as you suggest. From the description given at the beginning of the thread it was just needing a strip down , hope that helps.