Lanternman

I've only checked the single spare module under load.  As far as I was concerned driving the car, it was performing well - right up until the warnings!  I admit that at 12 years old they are probably end of life, but I would like to put it back working.  Yes I am from electro-mechanical background (Sub-station design) so can read circuit diagrams, so that would be most helpful John, thank you.

I have identified a 'Fuse like device' in the fuse box under the bonnet that is open circuit, initial checks show it is a noise filter, perhaps that needs replacing?  I'll dig a bit deeper on that one.

Thanks John,  it started with car being fine, then, as I was driving I had the Hybrid system warnings, ABS and stability control warnings, Battery degredation warning.  After a little research I decided to take the power pack out and check for a duff cell (I bought a spare to have ready).  Once apart I measured each cell, very little variation around 8.1V each.  Terminals had some corrosion so I cleaned them all (have all been checked 4 times now). I put it all back and .. No key sensor, the mechanical lock works the central door locks. Headlights work, horn works.  No ignition, no dashboard, no diagnostic circuit.  So I took the power Battery out again which is now in my garage.  The 12V Battery is good (12.8V steady).  I am puzzled by the Big Black 3rd cable from the bottom of the power pack, Is that a Ground return?  Thank for any guidance, David

That's great info John, I found that with the Battery pack out of the car and the safety plug put back in I get 318V across the pack.  Opening the box that hangs beneath the Battery modules I find two 'Control units'.  Do you know of any way to test or measure their status?  I can see one fuse that meters out OK.  Thanks, David

My apologies John, a "crossed thread".  My car has a good 12v Battery (12.8V)  and the cells in the power pack add up to 318.2V, all give good volts individually.  There is an open circuit between cells 19 and 20, where the wires are taken out to some controller I guess.  There is no volts on the pack output points.

Is there a fuse / relay somewhere?  Do I need to apply 12V to make something work?  I have checked the master key plug fuse (125A) and it is good.

Any suggestions for nest step?, thank you.

I shall investigate the power pack Battery further, thank you.  So far nothing explains the complete lack of 12V to the diagnostic circuits.  Any ideas anyone?

Fair enough.  I've already bought an old LS 430 just to see what it's like.  I love the 450h when it works ..... but probably won't bother with hybrid again.

Does anyone know of a conversion to effectively eliminate the hybrid system from my 450h and make it petrol only?

Yes, I will check actual power Battery volts and take it from there.  I have access to scanners, but as there is no power to the diagnostic circuits, they are no help!

That's good comment, thank you.  The interlock key has been in and out a few times, it only fits one way, the handle slides and clicks fully shut.  I will measure Battery pack volts next (when it stops raining!).  I know all modules are good and have similar volts.  I did triple check the module links before final re-assembly, but you never know, if the pack volts are suspect it will have to come out again.  I can see a scrapman looming .....

Thanks, it's a good 12.8V. It works headlights fine. The big Battery pack is good too.

Thanks guys,

A diagnostic techie picked me up on that, and yes, it is properly installed, thanks anyway.  But he seemed to think even with the Battery pack disconnected the diagnostic circuits (all 12V) should be live, but they are not.  It seems a bigger problem.

I had the Battery pack out to check it's condition after a dash warning.  It's getting end of life but the worst I saw was corroded terminals, so cleaned them and put it back together.

Now the car is effectively dead.  No dashboard. No diagnostics.  I only have headlights and horn, also when opening door drivers door with key (sensor not working) the other doors work on central locking.

I have checked fuses, all good.

Any help in what I should do next will be much appreciated.

Good diagnostics will tell you the state of the batteries in the tyre sensors.  Yours are due to fail about now (same as mine).  Batteries are not replaceable, so the whole sensor needs changing.  Can buy aftermarket.