Testing a coil

[Nodnol]

Hi I just need some help with testing my ignition coil, not Sure if I did it right
since i not to familiar with this multimeter, any help is welcome

[jeffrey8164]

Well, to start with, it’s not turned on.
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[Glenn]

[Nodnol]

Yea I know that but I don't know what setting to use

[APPLEGREENVW]

[bsairhead]

[Nodnol]

From positive to negative it's 4.0 measured at 200 and at + or - to center it's 7.37 measured at 20 k

[Franklinstower]

Here's two coils getting tested. In my ad it shows testing the cool primary windings.


https://seattle.craigslist.org/est/pts/d/mill-creek-vw-vanagon-rabbit-jetta/7716003452.html
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[Nodnol]

Alright now I know that the coil is good, next test is the condenser, what's the general resistance for it?

[jinx758]

Howdy ...

Testing a condenser, aka capacitor :

*Remove insulated female connector (or ring)& (usually green) wire from the negative side of coil
*Touch the end of wire to bare metal immediately.
This will discharge the stored voltage & render it harmless.
VERY IMPORTANT !
*Turn on DVOM & place on resistance (Ohms) function.
About 20K will do (what I use on my Fluke3).
*Hold red lead on end of wire & black lead on condenser body.
The display should jump UP in value, stopping around 19 or so & then show 1.0 .
This shows the condenser is able to charge.
*Place DVOM on DCvolts & hold leads opposite way.
The value on the display should jump DOWN.
This shows the condenser is able to discharge.

Simplified version but there ya go.

Technically the condenser holds a charge while the points are open & discharges when the points close.
It gives a jump start to the coil to help it ramp up quickly;
same principle as a stereo amplifier or a fan motor in an HVAC system uses a capacitor to help during peak usage needs - ie heavy bass or at start up.

Hope this helps ... stay safe

jinx

PS :
Some people just switch the leads with it in Ohms mode.
This is NOT the correct procedure & could harm the circuits over time.
I was dealing with battery chargers that ramped up to 49amps with 480/3phase AC when initialized.
SAFETY FIRST !
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[Nodnol]

Went ahead and tested it but I can't make sense of the results.

https://youtu.be/u3SSYU67t0c?si=qy2lmNKPMkeCrnfm


https://youtu.be/U-wzAJvn2ec?si=OQMyAf9WHcOSicE3

[jinx758]

Howdy ...

Ok, here we go.
I've never tested a condenser while on the car but not sure if that matters.

A few thoughts :
*Maybe the batteries aren't very potent in DVOM. They're either 3volt (AA batteries times 2 @ 1.5volts each) or 9volt.
*The circuits in that DVOM aren't sensitive enuff (read cheap).
*The engine is grounded through the transaxle strap. If that isn't shiny clean perhaps it could sway the reading.

The "M" on DCvolt setting stands for millivolt.
I think yours has a capacitance setting. It's opposite the 200M setting. It's all by itself & the symbol is a 2part or broken plus sign. This is also known as a diode tester. On an alternator test the magic # is 3.4-ish. Maybe store this in memory for future use.

Your test showed a falling reading from a discharged condenser - good. The charging reading did not cut off - not good.
A U-tube vid (or a member on here) cut one open & it shows a foil strip with an insulator on one side covered in a mystery waxy type semifluid. The length & width determined its values.

Condensers are cheap.
The Eschlin brand from Napa are usually OK.

Did you do ALL the tests in the video posted by APPLEGREENVW ?

Keep at it, you got this ... stay safe

jinx
_________________
" It's not valuable unless you learn something from an experience. " Henry Ford

It's not unlike the same difference ...

My Craigslist rescued 100 footer :
1971 Standard Bug
1776cc dual port
034 distributor
38mm EGAS Carburetor

[Nodnol]

I fully tested the coil and it's good, went ahead and removed the condenser so I can test it again, and now it's not giving any readings. Not sure what I'm doing wrong but Il probably just get a new one

[tasb]

Look for NOS new old stock not brand new. Echlin Standard brands or, if NOS Bosch. Do not buy a newly manufactured condenser.
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[runamoc]

Here is a schematic of a coil. To really test one, use a 'pulsing' relay and actually 'see' the spark

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[Blandyp]

[runamoc]