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Mon Sep 30, 2019 9:51 am

Bosch blue coil......9 220 081 083 (0 221 119 027)
Brazilian, I believe.

Anyway, from the 1 to the 15 side I'm showing 3.7 ohms. From the secondary post to 1 or 15 I'm showing 9,250. With the center wire connected, and testing from the end of the wire to 1 or 15 I'm getting right at 13,000 ohms.

Without the center wire it looks like I'm ok. But since the wire's in place when connected to the dizzy aren't I too high?

Mon Sep 30, 2019 10:12 am

Okay... I am gonna be easy on you. Check the primary resistance and the secondary resistance. The coil should be by itself and just the volt-meter.

Find out what the specs should be and see if the coil checks out by the manual.

Mon Sep 30, 2019 10:30 am

Said very well through Aircooled.net below (copied and pasted from their site):
http://vwparts.aircooled.net/12V-Bosch-Blue-Coil-with-Mounting-Bracket-00-012-p/00-012us.htm

"To check your existing coil, first make sure you have 12V going to the terminal 15 on the coil (Terminal 15 is positive, terminal 1 is negative (think of 1 sideways being negative). If you do, then pull the wire out of the center of the distributor with a rubber handled pair of pliers, and hold it about 1/4" from the metal clips that holds the distributor cap on. Have someone crank over the engine, and there should be a nice blue spark that goes from the end of the wire you pulled out of the center of the cap to the metal clip. It should look and sound strong, and should be easy to see, even in daylight. If it looks thin and weak (yellow is weak, blue is strong), then the coil windings may be giving out.

Another test for the Bosch Blue coil, is to use an Ohmmeter and with all the wires taken off the terminals of the coil attach the positive and negative, red and black, wires of the meter to first the terminal 1 and 15 that are printed (stamped) on the coil. You should have a reading of at least 3-4.5 ohms, which is the resistance reading inside the coil. A bad coil will show a higher reading then 3-4.5, you want less resistance.

Next, place the red or black lead from the meter to the center of the coil (secondary post), and to either one of the terminals, again 1 or 15 on the coil. You want 9500-10000 Ohms, sometimes you'll see less, but you don't want to see something like 11,000. Or if you have no reading in either case, the coil is trash."

Mon Sep 30, 2019 12:09 pm

No need to be easy on me.....I'm an admitted idiot. Still didn't get a direct answer to my question though :lol:

Mon Sep 30, 2019 12:42 pm

The secondary wires are resistor wires, done to decrease radio interference. There should be resistance through them. Just test the coil without the coil secondary wire.

Mon Sep 30, 2019 3:04 pm

Your measurements are pretty much correct. 3.7 ohms is a little high but that is likely due to not pressing your probes into the terminals tightly enough. Unfortunately, if you are trying to determine if a coil has failed those basic measurements are not enough. There is no easy way to test a coil other than to test it on a car and let it run long enough to get hot. An old coil tester that simulates the worst conditions for a coil will often tell if a coil is faulty, but those test instruments are hard to find nowadays. The easiest way is to compare the performance on the car with a known good coil and give it enough time so that heat will expose any faults. Fred

CNSRANCH wrote: Bosch blue coil......9 220 081 083 (0 221 119 027)
Brazilian, I believe.

Anyway, from the 1 to the 15 side I'm showing 3.7 ohms. From the secondary post to 1 or 15 I'm showing 9,250. With the center wire connected, and testing from the end of the wire to 1 or 15 I'm getting right at 13,000 ohms.

Without the center wire it looks like I'm ok. But since the wire's in place when connected to the dizzy aren't I too high?

Mon Sep 30, 2019 3:26 pm

Get a spark tester, like this

They are about $20 on Amazon

https://www.amazon.com/OTC-6589-Electronic-Ignitio...amp;sr=8-3

Drive it until it’s warmed up, then pull one of the spark plug wires off, clip the spark tester to ground with the plug wire on it, then start the engine and watch the spark at the tester. Make sure it doesn’t randomly skip sparks, and pay attention to the spark color. If the color is yellow or orange, the coil is getting weak and needs to be replaced.

Mon Sep 30, 2019 3:51 pm

Dale