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BenB8man

Member Since: 22 Mar 2017
Location: Norfolk
Posts: 427

2010 Defender 110 Puma 2.4 DCPU Stornoway Grey

Puma immobiliser

Afternoon Gents,

I've having some issues with my 2010 Puma 2.4 not starting. Hopefully this isn't complicated by an additional Immobiliser installed by previous owner. A Cobra system.

It started with a very occasional no crank when out and about. Usually a few jiggles with the key and it would start ok, so my assumtion from some posts on here was that it was the ignition switch starting to fail.

A few days ago I once again got this issue, but no amount of jiggling would resolve. A 10 minute wait and retry and it started. No issues with it cutting out or anthing like that. Once home, I've not managed to get it to crank on the key.

I have now replaced the ignition switch, which annoyingly has not solved the problem. No Crank. Even when trying it quickly, which by a few other posts could indicate crank then immobilised.

I've checked the start relay, works fine. I am getting +ve to the starter relay coil but only around -8v from on the ground side.

From what I understand this is supplied from the 10AS? Or is it from the ECM? I have noticed that although my Cobra system acts normally, on the plip, the standard LR plip isnt responding either (even with fresh batteries).

I have removed the 10AS to give it a look over for corrosion. Looks ok on the inside. Some very slight staining on the PCB by the socket which I will try to clean up.

I've also tried the instrument pin3-4 short. No change. Zero crank.

So, my thoughts at the moment are that the 10AS has issues. Dodgy ground maybe? Any where to start looking for grounding issues from the ECM/10AS?

Thanks. [/u]

20th Nov 2022 3:24pm

blackwolf

Member Since: 03 Nov 2009
Location: South West England
Posts: 16895

2007 Defender 110 Puma 2.4 DCPU Stornoway Grey

The starter relay activation coil gets +12v from the starter switch and the gnd is provided by the ECM so that the immobilizer can inhibit cranking and also (I think) so that cranking is inhibited when the engine is running.

If you can bridge The receptacles for pins 30 and 87 of the starter relay.with a suitable switch you can check if you then get reliable cranking, it will be independent of both ignition switch and ECM. The engine won't start without the ignition on and the immobilizer deactivated but should crank.

20th Nov 2022 4:01pm

BenB8man

Member Since: 22 Mar 2017
Location: Norfolk
Posts: 427

Yes I can get a crank if I bring 12v to 87 onthe relay.

I've just gone through and tested all the fuses under the steering wheel and don't seem to have voltage to quite a few of the fuses..

Back to the wiring diagrams I think!

Just to confirm, I've checked the fuses under the seat too.. All ok.

20th Nov 2022 4:07pm

BenB8man

Member Since: 22 Mar 2017
Location: Norfolk
Posts: 427

Interestingly, I've found ~6v going to pin 12 on the grey conector to the AS10.
This should be around 12v as its labeled "Battery Voltage".

Not sure where this is fed from currently.. Wiring diagrams say Fuse 7, which on the fuse box layouts say isn't used.. The mystery continues..

21st Nov 2022 5:54pm

BenB8man

Member Since: 22 Mar 2017
Location: Norfolk
Posts: 427

Well I think I have sorted the issue. Within the AS10 there was a tiny bit of corrosion/staining on the green plugs pins that just happened to be on pin 10 (crank output).

Unit was removed, cleaned with IPA and a toothbrush and all traces of staining removed.
For good measure I also resoldered/reflowed the connections for that plug as I've had that issue before with a very unreliable Volvo.

All back in and the result is... A start!!

Unfortunately it only managed 2 starts before the battery was exhausted. So its on the trickle charger and hopefully starts ok tomorrow!

I, on the other hand, am tired, wet and questioning Land Rover ownership.

21st Nov 2022 9:25pm

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