Am I testing this coil correctly?

Sounds like the test leads from the Actron are making better contact. Go to Radio Shack, buy a $3 package of jumper leads, and use the jumper leads to attach the test leads to the coil terminals.

As to which meter is better, they're probably both cheap Chinese junk and could well have come from the same factory. But in actual fact, those cheap digital meters aren't usually too bad. I'd expect the $3 model from Harbor Freight to work just as well, and I have two of those to sub for my $300 Fluke when I just want a meter for hacking around the garage.

I'd first make sure that there was good contact with the meter leads because a layer of oxide can insulate really well, even if you press the lead tips hard or scratch the contacts with them, as I learned when I kept measuring 0 VAC from a working wall outlet.

I've found that digital meters can give wierd ohms readings. For example, I had an approximately 200K resistor whose reading slowly rose, just if it was a capacitor charging up. Also I've read that digital meters aren't always reliable when measuring the resistance of a coil or capacitor because the meters put out short pulses instead of a steady voltage. I didn't encounter this with my Fluke 73 or Tenma, but maybe you should borrow an analog meter to check your coil's primary.

Yes.

This is K ohms not ohms.

The reading should not be 0 ohms. It could be that your meter does not show show zero accurately. Short the leads together to see if it reads 0 ohms. If it does not read 0 them the reading across the coil should be .24 to .3 ohms higher. If the reading constantly changes it is usually a problem with a bad connection. If the primary winding is really shorted (0 ohms) it is likely that it will damage the driver circuit.

I digital meter has a very high input impedance and could be reading leakage through the driver circuit.

*********Yep, you should be able to detect it easily. In that your car is not making any attempt to start reinforces your observation. *******Previously mentioned this is kilohms, but I suspect you have the numbers right, if not the prefix. And if so, you are well in the okay zone. ****** Lots of lower end vom's have this sort of problem with extreme measurements. And 0.0-0.3 ohms is low for some of them. To measure resistance accurately at low values requires equipment and attention to detail. But usually a very low reading is what you would expect from a good coil. On rare occasions a shorted primary winding might occur, and would give you about the same reading.

If you cant borrow a good vom, you might be able to jury rig a physics lab type test that would allow you to measure or estimate the actual resistance. For example, if you could deliver a measured and controllable current to the primary winding, and then measure the voltage across the winding, you can get a more accurate number. A quarter amp into the winding at

0.25 ohms would give you a voltage drop of 1 volt, easily measured, for example. (If you do this, make your measurements quickly and back off.) *********The only observation you have made that would suggest it is bad, at this point, is the failure to discharge high voltage. (oh well, the observation that the car wont start could be considered supporting evidence, I guess). But no measurement you have yet made on the coil supports the theory. ******** I would need to see a wiring diagram before commenting. I can envision designs whereby this would not be an unusual reading. That is the neat thing about electronics. About when you think you understand what is going on, somebody comes up with a different design. And I have no idea how Toyota approaches this.

show zero accurately. Short the leads together to see if it reads 0 ohms. If it does not read 0 them the reading across thecoilshould be .24 to .3 ohms higher.

Turns out it was on the wrong scale, as pointed out to me by the tech at the Toyota dealership. He tried it with my meter on the 200 scale and got a reading of .8 This is higher than specs, but the car was running with this coil.

However, what might be significant is that on this meter when I tightly connect the leads per your suggestion, on 2000K, 200K, 20K it reads 000, 00.0, 0.00 respectively, on the 2000 scale it reads 001, on the 200 scale it reads 00.4 Does this mean I should subtract .4 from anything read on that 200 scale?

How about these? The manual has several pages of diagrams but this seemed pertinent to the engine well. You'll need to zoom in a bit to see them. I tried to balance resolution with filesize. You can see them good enough to read them.

Yes if the meter reads 0.4 with the leads shorted you should subtract that from any readings in that range. FWIW my cheap $16 meter from wal-mart reads .3 with the leads shorted together on the 200 scale.

Ill take a look and see if I can make sense of it.

This is normal because of the resistance of the leads. On better meters you can "zero out" the display so you don't have to compensate for the resistance of the leads. If you subtract the .4 ohm restance of the leads from the .8 ohm reading of the coil then the .4 ohm resistance of the coil is close enough to specs to work properly.