1996 LS400 not starting. Immobiliser/fuel pump relay questions

[Howplum]

I'm trying to start a friend's car, which has stood for 3 years with a flat Battery, with a view to possibly buying it and saving it from being scrapped. I have put a fresh Battery in, but it won't even try to fire up after cranking for several seconds.  Tellingly perhaps, there is no smell of fuel, which could be expected after sustained cranking.

I am suspecting the immobiliser, which seems to be the most likely cause following the fitting of a new Battery, according my research on the internet. The central locking and alarm work just fine.

I spoke to a very helpful technician at the main dealer here in Milton Keynes, who said the immobiliser might need resetting, and to leave the ignition turned on for 10 minutes (although on the internet several people suggest 6) after connecting the Battery, but unfortunately that didn't work.

I obviously need to check for a spark, and see if the plugs are wet after cranking, just to be sure I'm not barking up the wrong tree.

If I could draw on the experience of others, I have several questions:

1. Is there another resetting procedure I could try? I understand the security systems (possibly Scorpion) were dealer fitted in this country.
2. It seems that pins 2 and 3 on the fuel pump relay (FPR) should receive a current with the ignition on. Pin 2 supplies the actuator and pin 3 supplies the pump, via pin 4, when the switch is closed. Is that correct? I found the attached diagram which helped.
3. Does the immobiliser cut the power supply to the FPR, or the pump, or something else?
4. Could I run a test wire from the Battery + terminal to pin 4 on the FPR socket, which according to my logic should tell me if the pump is working?
5. Does anyone know if Lexus tended to fit the immobiliser control unit in a consistent location, and if so, where? My assumption would be on the interior side of the front bulkhead, but I am reluctant to start dismantling underneath the dashboard just yet.
6. Once the control unit is found, does anyone know which wires are for the immobiliser unit? A wiring diagram would be very helpful.

I am reluctant to engage an electrician just yet, in case the solution is reasonably straightforward, so any guidance or advice would be much appreciated.

 

Lexus LS400 fuel pump relay circuit.odt