A friend sent this to me, and it is taken from the Snap-On e-newsletter. I don't know the date on this, but thought it might be helpful to my fellow Toyota owners. Anyone with a 3.0 V6 that can verify that this information is good and useful, I would appreciate it. Hope this is helpful to you guys.
Tech Tip: No Spark and/or No Injector Pulse on Toyota
Application: 1989-1995 Toyota Pickup & 4-Runner with 3VZE Engine.
Symptom: No Start.
Theory: The Ignition system on this engine uses a Distributor with three
Pick-up Coils inside and an external Igniter and Coil. The ECM uses the
signals generated by the three Pick-ups to control the Igniter, which
controls the negative side of the Coil for spark. The Igniter also sends a
signal back to the ECM for injector pulse.
The Test: The first place to start is to check the Pick-ups inside the
Distributor. If any of them are defective, nothing else is going to work,
not even the tap-test we're going to do later. The first step is to test
resistance on each of the three Pick-ups. You'll want to check them with
the harness unplugged from the Distributor. Identify the terminals on the
Distributor connector using the wire colors on the harness side.
Terminal-1: White..NE signal
Terminal-2: Red..G1 signal
Terminal-3: Black..G2 signal
Terminal-4: Green..G- signal
Between G- and G1, it should be 125 & 200 ohms. Between G- and G2, it
should also be 125 to 200 ohms. Between G- and NE, it should 155 to 250
ohms. All of these resistance specs are at ambient temperature. If checked
on a hot engine, the tolerances go up about 30 ohms. If any one Pick-up
fails the test, it needs to be replaced before any further testing. If all
three Pick-ups pass, we need to do a "tap-test" at the Igniter. Make sure
the connector is plugged back in at the Distributor. Go to the Igniter,
which should be mounted at the Coil. On the Igniter connector, locate the
Black/Blue wire and probe into it with a test-light. With the key on, tap
the alligator clip of the test-light on battery negative and watch for
spark out of the Coil. If you get no response, try tapping the alligator
clip on battery positive, again watching for spark out of the Coil. If
there's no spark in either case, check for battery voltage at the positive
side of the Coil. If that's okay, attach a second test-light from ground to
the negative side of the Coil and redo the tap-test at the Igniter. If the
test-light on Coil negative flashes during the tap-test, and you had
voltage on the positive side, you have a bad Coil. If the second test-light
did not flash on Coil negative, we need to check the remaining wires at the
Igniter. Make sure you have battery voltage on the Black/Red wire at the
Igniter with the key on. If that's okay, make sure you have continuity on
the Black/White wire between the Igniter connector and the negative side of
the Coil. Make sure the Igniter itself is grounded properly to its mounting
surface on the truck, no rust or corrosion. The last check will be to make
sure the Black wire does not show full continuity to ground. This wire goes
to the Tachometer, and if grounded somewhere in the harness, will keep the
Igniter from working. If all of these things pass inspection, chances are
good you have a defective Igniter. Be sure you check resistance on the Coil
to be sure we don't damage a new Igniter. The primary side should be 0.4 to
0.6 ohms. Secondary should be 10,200 to 13,800 ohms.
The Fix: Replace the defective parts determined by the above testing. Don't
forget, if you do end up replacing the Igniter, double check Coil
resistance to avoid damaging a new Igniter.