Engine turns over but won't start

may need to replace both the camshaft sensor, & crankshaft sensors, I believe that both are located near distributor/ & timing belt cover & top of engine.

Check batry terminals are secure & free from corosion, check security of earth strap to engine & main power wire on starter, if ok have the batry load tested to ensure it can perform under load as the starter needs a lot of current. Have you tried a jump start?

If the engine won't crank with compression in the cylinders, either the head gasket has blown or something else major has happened.
You will have to get it towed to a shop.
If it cranks normally but won't start, you have to figure out if it is a fuel or ignition problem.
Did the temp gauge show it was overheating before it died ?

Did you ever figured it out on the GS400?

If it is a 3.8 engine change the crank sensor,they go bad on the 3.8 engines.

i know industry jargon can be confusing, but lets try this. if it turns over but won't start, it could be your ''ignition module'' that sits on top of the vave cover on the motor or it might be the fuel pump or filter. make sure when you crank the engine that the key is all the way turned or it may not always make a proper contact to activate the ignition module. iv'e seen this before & had to change the ignition switch & all worked ok after that. i would need to know engine lt size to give you more details on the matter. please get back to me.

The 'Keyless Entry & Burglar Alarm System" is activated. You must 'Disarm' the system using the Keyless Entry Remove (Key Fob) to "Reset" the system. The reason the engine won't start is due to the burglar alarm - it has a "Starter Kill" circuit which is activated when the alarm is activated. The alarm must be DEactivated to DEactivate the 'Starter Kill' circuit.
Another way to start the engine is to get in the car, put the key in the ignition and turn it to 'ON" and wait 3 to 5 minutes until the emergency flashers stop/turn off. Afterward, you should be able to start the engine. NOTE: This does NOT reset the burglar alarm. It will go off again when you enter the vehicle without using the remote/key fob.

Could try the crank sensor, that is where I would start. Next would be the timing & compression.

It could be that your fuel pump is not getting enough fuel to the engine to start it. Is your starter turning over or trying to start the engine.

Checked Cables how?

Looking & Touching isn't doing anything

You have to do a voltage drop test or remove
& clean the ends. I would do both

Remove the starter & have it tested at parts store,
assuming you don't know how to do a voltage or
current test while cranking.