90 MONTERO V-6 ENGINE COMPUTER--FASTEST WAY TO TEST ???

Get a 12v LED and 5 feet of wire from the nearest electronics store. The ECU test connector is under dash somewhere. Usually its above the brake pedal,but could be in the glove compartment.

You can also use an analog voltmeter.

The test pins are diagonally opposite. If the ECU is working, you will get flashing on the LED either as set of long and shorts which define the error code(s) or LED always on or off.

However, the FIRST thing to do is verify that the ECU is not fried. Take the ECU out and take off the cover. Look for burned components or exploded or leaking electrolytic cap cans.

The SECOND thing to do is verify that the ECU isgetting power. There's a big relay near the ECU: this is the MPI relay that routes power to the ECU and also controls power to the fuel pump. You can test that the relay is getting power and passing it to the ECU when the IGN is on. Likewise that the fuel pump is getting power.

Perhaps you should invest in a workshop manual.

The CEL should light up for a few seconds when the IGN is switched on, then turn off. If its not coming on at all, either

a) the ECU is not getting power (via the MPI relay); or b) the ECU is fried.

See my previous post.