OK a couple of things, the 1HD-T does not have an oil
pressure light.
There is an oil
pressure gauge and sender, and there is an oil
level light,
So that's cleared that up.
The oil pressure gauge on any vehicle is pretty useless even if accurate which the 80 one is until it wears, more of that later. In the 80 sump is an oil
level sensor and the dashboard warning is amber, if the level in the sump falls then the light comes on. I was under the impression that the oil level light can only come on when you switched on the ignition and went out after starting the engine, and then would not come on again until the engine was switched off and restarted, that is the circuit is disabled after the engine is started. I was once told this is not the case and the light would come back on if the oil level fell, so I am not not sure about this as the oil in the sump falls significantly when the engine is running, so it is feasible that if the oil level was low and you were traversing some rough ground then perhaps the sensor would trigger the dash warning? The oil level sensors do go bad in particular if oil changes are not regular, they in effect 'gum up' so could trigger a low reading assuming they can when the engine is running even if the level is correct.
So to the the oil pressure sensor, when new they are fairly accurate but they do wear but they are adjustable! In the quest for dashboard accuracy I not only calibrated the oil pressure sensor but also the dashboard indication at the same time, and whilst in there I also changed a couple of electronic components in the temperature gauge so it now shows the true temperature of the engine. and of course the fuel level gauge was done at the same time. After calibrating the oil pressure sensor and gauge I also fitted a 'T' in the block so the gauge AND an oil pressure switch could be fitted and a light into the dashboard. I did once consider myself an avid dashboard watcher, but the truth is no one is going to notice an oil pressure gauge slowly falling as your oil is dripping out of the bottom of the engine due a a leak or whatever but a light will catch your attention.
I done other 'stuff' with the dashboard for example what was going on under the bonnet, this is listed in my long running thread on 'MUD'. here is the dashboard insert that is left blank in the manual cars:
Builds - My LC 80 thread. - [Leaving Land Cruiser Club] POST 299
And here when lit up:
Builds - My LC 80 thread. - [Leaving Land Cruiser Club] POST 306
So this 'module' shows different information, for example low oil pressure light, engine cooling fan on, low engine coolant, and so forth. the oil pressure light and low water lights are linked to a buzzer as well, there are switches that enable the buzzer (which will drive you crazy) if you need the ignition on without starting the engine for example when looking for a faulty indicator.
Give me a shout if you want further information, but my MUD thread pretty much has everything done to my car, including service intervals and so forth.
Stay safe.
Regards
Dave
EDIT: Having a bit of a 'moment' this morning, so have had to correct some typos....well a lot of them actually. LOL!