If you don't have a wiring diagram for this car suggest you find one. A Haynes shop manual has these or try your local libraries auto repair section for something like Motor repair books or reference desk may have OEM shop manuals. The AutoZone website may have something in the site vehicle repair guide section.

Are the check and alt light bulbs OK (not burned out), as in sometimes they are illuminated?

You stated the issues are the engine quits, the check and alt lights do not come on after the engine quits and when the engine quits nothing happens when the ign key is turned to start.

And that the car has no theft system either Toyota installed or aftermarket.

The alt dash light and starter systems are wired through the ign switch. Might check the ign switch.

The check light receives power from the Gauge fuse. In the dash wiring the check light is on the same power buss as the tach and speedometer.

To illuminate the light, the computer grounds the negative terminal of the bulb to complete the circuit.

The computer is behind the glove box. Might locate the computer, find the Green/Red wire from the engine check bulb. Unplug that harness from the computer and ground that wire, ign switch on to determine if the bulb now comes on.

Neither the alt or starter circuits run through the engine computer. The things they have in common are the Gauge fuse, ign key (AM1 circuit-Note the ign key is two separate switches built into one switch), AM1 fusible link and 100A Alt fusible link.

When the ign which to ON, the AM1 fuse also powers the wipers and turn signals.

When the ign is to ACC the fuse powers the radio and cig lighter.

Next time the engine dies check if the wipers and turn signals still work.

If the bulbs are bad, light will not come back on, but light did come back on every time I reset the computer by resetting the Main Engine Repaly.

I tested turn signal, radio and wipper worked when there is no Battery light and check engine light. but no crank, and if I turn the key, the clock goes way and I release it, the clock comes back on. does that mean ignition switch is fine?

Is engine shut off problem a separate problem or it also related to No Battery and Check engine light problem? they happen at the same time.

can a bad ignition switch shut off engine when it is runing?
if it does then, I will buy one and test it.
Yesterday I also thought about replacing a circuit replay or fuel pump but it seems they may not be the problem.
I already replaced the second ignition switch, ignition cables, spark plugs, main engine relay, head relay. just no luck.

Thanks Joey,

John

did not find anything that can help me.
 

my question is if the ignition switch is not funtioning correctly, may a running engine shut off?
after firing up the car, the ignition switch does nothing right? that means engine shutting off problem nothing to do with it.
Just no idea.
This is my 10 years puzzle.

The ign switch being ON continues to supply power to the engine computer and alternator.

I will replace the ignition switch with weekend.
see how it goes.

Thanks Joey,

John

I tried that site, and no luck.
I changed the ignition switch today, and the same result; engine starts and shut off after a minute.
everything works when engine dies except there is no battery and check engine lights( it looks no power to the ignition system. i guess computer may think that the engine is still running)

could it be crankshaft position sensor?

Thanks,

John

A bad crank sensor can cause the engine not to start but would have no affect on the dash lights.

Guessing the car wiring has a problem.

Did you find a wiring diagram yet?

The alternator system is separate from the engine computer. Even if the computer turned the engine off, the alt light would come on.

10 years mystery was solved
 

Hey Joey,
I worked on the car last saturday.
It was the connection problem. There was bad contact point at the main relay which controls the ignition and engine status.

I replaced the entire relay box with a used one, and the problem is gone.
I went to a couple of car forums and nobody found the cause. Now I found it. It was easier this time becase there was no check engine and battery light at all due to the connection point was completely burnt.
I am so exited about it.

Thank you very much for your support.

John

Thanks for posting back with the fix.

Great job on finding a very difficult problem, your perseverance paid off!!

Good job!

Joey