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I think Iíve fried my Pertronix - how do I test?
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Red Devil
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PostPosted: Tue Apr 16, 2019 8:29 am    Post subject: I think Iíve fried my Pertronix - how do I test? Reply with quote

Like a fool Iíve just reinstalled my engine (62 bus but converted to 12v with alternator and 1600 engine) but realised I had one wire which connects to the coil ďleft overĒ and I wasnít sure which side it connected to. As it was black I went with the -ve side!

On the +ve side weíre the red Pertronix wire and the one which runs to the fuel cut off solenoid and choke. The only -ve wire was the black Pertronix wire.

Hence, I tried to start the bus but it would not fire. Fuel getting through ok. I have no spark when grounding a plug on the block. Having dug out an old wiring diagram I now think the wire I wasnít sure of should have gone to the +ve also. Would this likely fry my Pertronix hence no spark?

The wire appears to run from the rear to the front of the bus so doesnít connect to anything else in the engine bay.

Iím happy with mechanics but not electrical so is there an easy way for me to check/test the Pertronix unit? Of course it could be something else but my gut feeling is this is now an expensive mistake.

Thanks for any help or advice which can be offered.

Steve
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easy e
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PostPosted: Tue Apr 16, 2019 9:22 am    Post subject: Re: I think Iíve fried my Pertronix - how do I test? Reply with quote

The forum search function is your friend.
You don't need to test it... just get the 'ol wallet out again.
tallman206 wrote:
Reverse wirirng WILL blow the Pertronix.
I think I cooked my Pertronix...
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Red Devil
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PostPosted: Tue Apr 16, 2019 9:43 am    Post subject: Re: I think Iíve fried my Pertronix - how do I test? Reply with quote

Thanks. I didnít actually reverse the wiring for the Pertronix. I connected a different wire which I think should have been on the positive side to the negative side. Does this have the same impact?

Thanks

Steve
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easy e
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PostPosted: Tue Apr 16, 2019 9:53 am    Post subject: Re: I think Iíve fried my Pertronix - how do I test? Reply with quote

To test it...
Hook it up like it's supposed to be... and check for spark.

If no spark... check your coil.
Mr.Duncan wrote:
http://www.vw-resource.com/tune-up.html#coil

Remove all of the wires from the coil terminals.

Attach the positive and negative, red and black, wires of the Ohmmeter to Terminal #1 and Terminal #15 that are printed (stamped) on the coil. You should get a reading of beween 3 and 4.5 ohms, which is the resistance inside the coil. A bad coil will show a higher reading than 3-4.5 ohms - 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, either #1 or #15. You want 9,500-10,000 Ohms. Sometimes you'll see less but you don't want to see something like 11,000 Ohms. If you have no reading in either case, the coil is trash.

If your coil is good... your ignition module is probably bad.
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flemcadiddlehopper
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PostPosted: Tue Apr 16, 2019 6:37 pm    Post subject: Re: I think Iíve fried my Pertronix - how do I test? Reply with quote

You could also put a spark tester on the coil and hold a soldering iron near the distributor. The electromagnetic field of it will trigger the pick-up and make the coil fire. No spark, bad pick-up, or coil. Test light between neg wire for the coil and power. If light flickers with same test, bad coil.(good pick-up and module).

Gordo.
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Glenn Premium Member
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PostPosted: Tue Apr 16, 2019 6:46 pm    Post subject: Re: I think Iíve fried my Pertronix - how do I test? Reply with quote

Youtube has tons to videos... here's one.


Link

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Red Devil
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PostPosted: Wed Apr 17, 2019 12:41 pm    Post subject: Re: I think Iíve fried my Pertronix - how do I test? Reply with quote

Many thanks all. New unit fitted today and up she fired. Just need to take it on a run now and check everything else Iíve been fiddling with seems to work ok.

Appreciate your time in responding to my questions.

Steve
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telford dorr
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PostPosted: Wed Apr 17, 2019 4:27 pm    Post subject: Re: I think Iíve fried my Pertronix - how do I test? Reply with quote

Interesting. This confirms what I have long suspected about these modules:

- the coil drive is "on" by default. Thus, with the key on and engine not running, power is being dumped into the coil, heating it up. So; either start the engine or turn off the key. Otherwise, you'll cook your coil. If you must do testing with the key on and the engine not running, unplug the red module wire from the coil.

- these units pulse the coil off for a moment when a magnet passes the sensor, then immediately turn the power back on again. I suspect that you'll find that the "off" time is fixed (need to confirm with a 'scope). This means that there is no fixed "dwell angle" like a points ignition has. I suspect it is optimized for top rated engine speed, and the effective dwell angle is likely very much greater than stock as the engine speed decreases. This means that the coil will run MUCH hotter than it would with a points setup. Can the coil take it? Apparently, for a while....
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PookAndThePack
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PostPosted: Wed Jun 19, 2019 1:00 pm    Post subject: Re: I think Iíve fried my Pertronix - how do I test? Reply with quote

So, I did fry it. But now, with new distributor in, an empi, it still wonít start. The coil test to read 3.0 ohms. Spark going to distributor. What could I have fried?
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PostPosted: Wed Jun 19, 2019 1:02 pm    Post subject: Re: I think Iíve fried my Pertronix - how do I test? Reply with quote

PookAndThePack wrote:
So, I did fry it. But now, with new distributor in, an empi, it still wonít start. The coil test to read 3.0 ohms. Spark going to distributor. What could I have fried?

It might be bad out of the box.
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PookAndThePack
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PostPosted: Wed Jun 19, 2019 1:58 pm    Post subject: Re: I think Iíve fried my Pertronix - how do I test? Reply with quote

Put in old vacuum advance distributor. Spark gets to spark plugs. (Pulled number 3 out and grounded it while friend cranked engine. What else could I have fried? Itís a 67 bus, but engine is code AK , so from 73í. Still wonít turn over. Is there something electronic in fuel delivery system that may have fried? Iíve not check to see if fuel pump is working.
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srfndoc
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PostPosted: Wed Jun 19, 2019 7:08 pm    Post subject: Re: I think Iíve fried my Pertronix - how do I test? Reply with quote

Check your points gap. Did you statically time it with the new dizzy?
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telford dorr
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PostPosted: Wed Jun 19, 2019 7:29 pm    Post subject: Re: I think Iíve fried my Pertronix - how do I test? Reply with quote

In case one of the distributors was a "009' style, keep in mind that the wire positions in the cap are 90 degrees different than a stock distributor...
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PostPosted: Wed Jun 19, 2019 7:35 pm    Post subject: Re: I think Iíve fried my Pertronix - how do I test? Reply with quote

telford dorr wrote:
In case one of the distributors was a "009' style, keep in mind that the wire positions in the cap are 90 degrees different than a stock distributor...


^^ This and make sure your point gap/dwell is correct. Sometimes a bad condenser will make it not run either.
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