# Help Testing AEG Coilpack with Multimeter



## Vee AH SEX (Jun 1, 2010)

I was wondering if some one could walk me through the process of testing a coil pack and provide me with the what the resistance should be reading. I have an idea about how to do it but I'de like to hear it from some one who's done it before. Thanks!


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## Anony00GT (Mar 6, 2002)

Use the voltmeter to test for power and ground at the connector. Use an LED test light to test for pulse from the ECU while cranking. I don't know pins and wire colors offhand, that info can be found in the relevant service manual. If all tests good, replace coil.


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## unstable01 (Jun 10, 2013)

I was going to respond to this yesterday but I didn't really have a detailed answer for you. I've got an 01 Land Rover that has eaten up a few coil packs and from what I've already experienced with VW, it seems their ECU and reporting system for errors is considerably better than Rover.

With that said, what makes you think you have a bad coil pack? Is the car running rough? Do you have any lights on the dash and have you pulled codes?

In both instances that I had coil pack problems on the Rover, the vehicle had a check engine light lit and codes showed multiple misfires across a single bank...which left only the wires and the coil pack as the potential culprit (barring wiring to the pack itself).

There are some videos on testing resistance on coil packs, however; I've heard of multiple instances where a pack bench tests fine but is problematic. Additionally, you will need to determine the pin-outs of the connector on the coil in order to complete this procedure.

Finally, you can visually inspect the coil for any cracks/bubbling etc. From what I understand, the VW's suffer from coil packs that crack and fire their load into ground instead of down the wire. You can usually test for this by filling a spray bottle with water and misting lightly around the coil and ignition wires at nighttime while the car is running. If you see sparks, you've got problems.


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## NickPDX1980 (Mar 26, 2010)

Sorry to bump an old thread but I was wondering if the OP ever got help with testing with the multimeter. I have been attempting to do the same on my 2000 Jetta with an AEG engine as well.



In the picture above I have been able to test the resistance between all of these pins and the resistance varies. Not sure what it should read out as or if it should remain consistent either.



But if I try to test the resistance from any of those numbered pins in the connector to any of these pins where the wires connect I can never get any read out. If I check from between these pins, the two on the left get a reading and the two on the right get the same reading but nothing across from the left to right ... which seems correct.

I am testing because I am getting a cylinder 3 misfire code. Car is a 2000 Jetta AEG with ~180k miles on it. The coil pack has never been replaced.

Any help is appreciated!


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## dogdog (Jul 26, 2007)

check page 28A-11 and 28A-12 of the bently manual it shows you who to check the coils.... sorry couldn't attach pictures here.....

basically it says .... the power output stage can not be directly tested..... but the signal from the ECM along with power and ground can easily be tested with voltmeter and LED test light as what Anony00GT mentioned. 

ignition coil secondary high voltage side can be tested with ohm meter by checking the OHM reading if between Plug 1 & 4 and between Plug 2 & 3 on the high side. the ohm reading should be 4000 to 6000 ohm @68 deg F.... and check for coil connection open and short circuit to ground..... that is all it says....


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## Anony00GT (Mar 6, 2002)

Yeah dogdog is right. The diagnostic method is to verify that everything is working properly on the car side. If it is, and the spark tester shows no spark output from the coil, replace the coil.


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